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1 Industry News (November/December 2013)

The complete Industry News section from the November/December 2013 issue of Gear Technology.

2 Industry News (October 2012)

The complete Industry News section from the October 2012 issue of Gear Technology.

3 Grinding Bevel Gears on Cylindrical Gear Grinding Machines (January/February 1994)

Power train designs which employ gears with cone angles of approximately 2 degrees to 5 degrees have become quite common. It is difficult, if not impossible, to grind these gears on conventional bevel gear grinding machines. Cylindrical gear grinding machines are better suited for this task. This article will provide an overview of this option and briefly introduce four grinding variation possibilities.

4 Metallurgical Aspects to be Considered in Gear and Shaft Design (March/April 1999)

In his Handbook of Gear Design (Ref.1), Dudley states (or understates): "The best gear people around the world are now coming to realize that metallurgical quality is just as important as geometric quality." Geometric accuracy without metallurgical integrity in any highly stressed gear or shaft would only result in wasted effort for all concerned - the gear designer, the manufacturer, and the customer - as the component's life cycle would be prematurely cut short. A carburized automotive gear or shaft with the wrong surface hardness, case depth or core hardness may not even complete its basic warranty period before failing totally at considerable expense and loss of prestige for the producer and the customer. The unexpected early failure of a large industrial gear or shaft in a coal mine or mill could result in lost production and income while the machine is down since replacement components may not be readily available. Fortunately, this scenario is not common. Most reputable gear and shaft manufacturers around the world would never neglect the metallurgical quality of their products.

5 Suitability of High Density Powder Metal Gears for Gear Applications (January/February 2001)

The implementation of powder metal (PM)components in automotive applications increases continuously, in particular for more highly loaded gear components like synchromesh mechanisms. Porosity and frequently inadequate material properties of PM materials currently rule out PM for automobile gears that are subject to high loads. By increasing the density of the sintered gears, the mechanical properties are improved. New and optimized materials designed to allow the production of high-density PM gears by single sintering may change the situation in the future.

6 Powder Metal Magic (August 2012)

Capstan Atlantic, located in Wrentham, Massachusetts, produces powder metal gears, sprockets and complex structural components. The company has provided unique powder metal products in a variety of industries including automotive, business machines, appliances, lawn and garden equipment and recreational vehicles.

7 Morphology of Micropitting (November/December 2012)

Understanding the morphology of micropitting is critical in determining the root cause of failure. Examples of micropitting in gears and rolling-element bearings are presented to illustrate morphological variations that can occur in practice.

8 Large Pinions for Open Gears - The Increase of Single Mesh Load (January/February 2013)

This paper introduces mandatory improvements in design, manufacturing and inspection - from material elaboration to final machining - with special focus on today's large and powerful gearing.

9 Heat Treat 2013 (March/April 2013)

An overview of the latest technology and trends in heat treating.

10 Product News (June/July 2013)

The complete Product News section from the June/July 2013 issue of Gear Technology.

11 Tooth Root Optimization of Powder Metal Gears - Reducing Stress from Bending and Transient Loads (June/July 2013)

This paper will provide examples of stress levels from conventional root design using a hob and stress levels using an optimized root design that is now possible with PM manufacturing. The paper will also investigate how PM can reduce stresses in the root from transient loads generated by abusive driving.

12 New ECM Furnace Improves Manufacture Efficiency of PM Components (March/April 2014)

The heat treatment processing of powder metal (PM) materials like Astaloy requires four steps -- de-waxing, HT sintering, carburizing and surface hardening -- which are usually achieved in dedicated, atmospheric furnaces for sintering and heat treat, respectively, leading to intermediate handling operations and repeated heating and cooling cycles. This paper presents the concept of the multi-purpose batch vacuum furnace, one that is able to realize all of these steps in one unique cycle. The multiple benefits brought by this technology are summarized here, the main goal being to use this technology to manufacture high-load transmission gears in PM materials.

13 Powder Metal Gear Design and Inspection (September/October 1996)

Powder metallurgy (P/M) is a precision metal forming technology for the manufacture of parts to net or near-net shape, and it is particularly well-suited to the production of gears. Spur, bevel and helical gears all may be made by made by powder metallurgy processing.

14 Things Are Heating Up in 2015 (March/April 2015)

In this special section, our editors have gathered recent news and information related to the heat treatment of gears. Here you’ll find a comprehensive assortment of news and upcoming events that will help you understand the various heat treatment processes available for gears and choose the best option for your projects, whether you heat treat in-house or send your gears to a commercial heat treating provider.

15 Product News - Gear Expo 2017 (November/December 2017)

This special edition of Product News includes highlights from Gear Expo 2017 of new products that caught the editors' eyes.

16 Industry News (November/December 2017)

Gear Technology hosts dinner for technical contributors to the gear industry during this year's AGMA Fall Technical Meeting and Gear Expo in Columbus, OH. Plus other news from around the industry.

17 Influence of Different Manufacturing Processes on Properties of Surface-Densified PM Gears (September/October 2018)

The properties of both shot-peened and cold rolled PM gears are analyzed and compared. To quantify the effect of both manufacturing processes, the tooth root bending fatigue strength will be evaluated and compared to wrought gears.

18 The Additive Advantage (September/October 2019)

How 3-D printing is changing the powder metal performance game.

19 Industry News (January/February 2016)

Latest new from the Gear Industry

20 ...And from the Industry (October/November 1984)

Industry News from October/November 1984 Gear Technology.

21 Influence of the Contact Conditions in Cold Rolling on the Density Profile of Powder Metallurgical (PM) Gears (June 2020)

Due to production by pressing and sintering, PM gears are porous. Since pores reduce the loaded area and are also probable crack initiators, the porosity determines the strength of the PM component. PM gears can be densified to increase their local density and, therefore, the load-carrying capacity. PM gears are compacted locally since they are mainly loaded directly at the surface. A common process to densify PM gears locally is the cold rolling process. The contact conditions in the cold rolling process determine the density profile and, therefore, the material properties of the PM component. The influence of the contact conditions in cold rolling of PM gears on the resulting density profile is yet to be investigated.

22 IMTS 2014 Product Preview (August 2014)

An in-depth look at the major booths with the latest technology used in gear manufacturing.

23 Alternative Gear Manufacturing (July/August 1998)

the gear industry is awash in manufacturing technologies that promise to eliminate waste by producing gears in near-net shape, cut production and labor costs and permit gear designers greater freedom in materials. These methods can be broken down into the following categories: alternative ways to cut, alternative ways to form and new, exotic alternatives. Some are new, some are old and some are simply amazing.

24 Wear Investigation of Finish Rolled Powder Metal Gears (September/October 2017)

When manufacturing powder metal (PM) gears lead crowning is not achievable in the compaction process. This has to be accomplished either by shaving, grinding or honing. Each of these processes has their merits and draw backs. When employing rolling using a roll burnishing machine lead crowning can be accomplished but due to errors in profile a hard finishing operation such as grinding is used by the industry. In this paper a helical PM gear that has sufficient tolerance class after rolling has been tested in a test rig for durability and the wear has been studied.

25 Industry News (May 2020)

The complete Industry News section from the May 2020 issue of Gear Technology.

26 Selection of Material and Compatible Heat Treatments for Gearing (May/June 1986)

The manufacturing process to produce a gear essentially consist of: material selection, blank preshaping, tooth shaping, heat treatment, and final shaping. Only by carefully integrating of the various operations into a complete manufacturing system can an optimum gear be obtained. The final application of the gear will determine what strength characteristics will be required which subsequently determine the material and heat treatments.

27 Comparison of PM-HSS and Cemented Carbide Tools in High-Speed Gear Hobbing (September/October 2009)

This article examines the dry hobbing capabilities of two cutting tool materials—powder metallurgical high-speed steel (PM-HSS) and cemented carbide. Cutting trials were carried out to analyze applicable cutting parameters and possible tool lives as well as the process reliability. To consider the influences of the machinability of different workpiece materials, a case hardening steel and a tempered steel were examined.

28 Effects on Rolling Contact Fatigue Performance--Part II (March/April 2007)

This is part II of a two-part paper that presents the results of extensive test programs on the RCF strength of PM steels.

29 Effects on Rolling Contact Fatigue Performance (January/February 2007)

This article summarizes results of research programs on RCF strength of wrought steels and PM steels.

30 Utilization of Powder Metal and Shot Peening Residual Stress to Maximize Cost and Performance Benefit of Highly Loaded Gearing (November/December 2005)

This article focuses on bending fatigue strength improvements of P/M gearing from recent improvements in P/M technology, combined with shot peening.

31 Bending Fatigue, Impact and Pitting Resistance of Ausform-Finished PM Gears (June 2010)

The powder metal (P/M) process is making inroads in automotive transmission applications due to substantially lower costs of P/M-steel components for high-volume production, as compared to wrought or forged steel parts. Although P/M gears are increasingly used in powered hand tools, gear pumps and as accessory components in automotive transmissions, P/M-steel gears are currently in limited use in vehicle transmission applications. The primary objective of this project was to develop high-strength P/M-steel gears with bending fatigue, impact resistance and pitting fatigue performance equivalent to current wrought steel gears.

32 PM Design Winners Announced at Powdermet 2011 (June/July 2011)

Design innovation, superior engineering properties, high end-market visibility and sustainability distinguish the winners of the 2011 Design Excellence awards, the annual powder metallurgy (PM) design competition sponsored by the Metal Powder Industries Federation.

33 Austempered Nodular Cast Irons (March/April 1985)

Austempering heat treatments (austenitizing followed by rapid cooling to the tempering temperature) have been applied to nodular irons on an experimental basis for a number of years, but commercial interest in the process has only recently come to the surface.

34 Factors Influencing Fracture Toughness of High-Carbon Martensitic Steels (January/February 1989)

Plane strain fracture toughness of twelve high-carbon steels has been evaluated to study the influence of alloying elements, carbon content and retained austenite. The steels were especially designed to simulate the carburized case microstructure of commonly used automotive type gear steels. Results show that a small variation in carbon can influence the K IC significantly. The beneficial effect of retained austenite depends both on its amount and distribution. The alloy effect, particularly nickel, becomes significant only after the alloy content exceeds a minimum amount. Small amounts of boron also appear beneficial.

35 Mechanical Behavior and Microstructure of Ausrolled Surfaces in Gear Steels (March/April 1995)

Ausforming, the plastic deformation of heat treatment steels in their metastable, austentic condition, was shown several decades ago to lead to quenched and tempered steels that were harder, tougher and more durable under fatigue-type loading than conventionally heat-treated steels. To circumvent the large forces required to ausform entire components such as gears, cams and bearings, the ausforming process imparts added mechanical strength and durability only to those contact surfaces that are critically loaded. The ausrolling process, as utilized for finishing the loaded surfaces of machine elements, imparts high quality surface texture and geometry control. The near-net-shape geometry and surface topography of the machine elements must be controlled to be compatible with the network dimensional finish and the rolling die design requirements (Ref. 1).

36 The Effect of Metallurgy on the Performance of Carburized Gears (March/April 1996)

Gears are designed to be manufactured, processed and used without failure throughout the design life of the gear. One of INFAC's objectives (*see p.24) is to help manufacture of gears to optimize performance and life. One way to achieve this is to identify failure mechanisms and then devise strategies to overcome them by modifying the manufacturing parameters.

37 Gear Material Quality: How To Judge It...Pitting: How To Prevent It (March/April 1993)

How do we know when the gear material we buy is metallurgically correct? How can we judge material quality when all gear material looks alike?

38 The Art of Versatility - Grinding at Gear Expo and EMO (October 2013)

Whether you spent time at Gear Expo in Indianapolis or EMO in Hannover, there was certainly new technology attracting attention. Machine tools are faster, more efficient and can integrate numerous functions in a single setup. Grinding technology is turning science upside down and inside out with high-speed removal rates and increased throughput.

39 Crash Course on New Technology (August 2013)

It's nice to see old friends. It's also advantageous to make new ones. Gear Expo has always been a family reunion of sorts, but it's first and foremost an opportunity to show off the latest and greatest technologies that are impacting the gear industry today. With this in mind, Gear Technology recently spoke with those responsible for putting the Fall Technical Meeting (FTM) and Gear Expo 2013 together in Indianapolis.

40 Hardness Testing (May 2013)

This back-to-basics article describes the main methods used for hardness testing of gears: Rockwell, Brinell, Vickers and Knoop.

41 Design of a Flexible and Lean Machining Cell, Part I (June/July 2013)

Although a cell is dedicated to produce a single part family, it must have the requisite equipment capabilities, routing flexibility, cross-trained employees and, to the extent possible, minimal external process dependencies. Cells are often implemented in job shops since they provide the operational benefits of flowline production.

42 Bearings Education - A Lot to Learn (June/July 2013)

Bearings ain't beanbag. They are complicated. They are big-business. They are often counterfeited. They are used in virtually anything that moves. But it is the "complicated" part that challenges OEMs, job shops and other operations, and, most of all, their employees. Add to that the countless other entities around the world that are intimately involved with bearings and you can arrive at a semblance of an idea of just how important these precious orbs can be to a successful operation.

43 The Latest Gear Generation - Interview with Jan Klingelnberg (October 2013)

This is the first of a new series of Gear Technology profiles of individuals you should know in the gear industry.

44 Off-Highway Gears (June/July 2013)

Market needs push in 2013, but will it get one? The construction/off-highway industries have been here before. New equipment, technologies and innovations during an economic standstill that some have been dealing with since 2007.

45 New Methods for the Calculation of the Load Capacity of Bevel and Hypoid Gears (June/July 2013)

Flank breakage is common in a number of cylindrical and bevel gear applications. This paper introduces a relevant, physically based calculation method to evaluate flank breakage risk vs. pitting risk. Verification of this new method through testing is demonstrably shown.

46 How to Design and Install Bevel Gears for Optimum Performance - Lessons Learned (June/July 2013)

Bevel gears must be assembled in a specific way to ensure smooth running and optimum load distribution between gears. While it is certainly true that the "setting" or "laying out" of a pair of bevel gears is more complicated than laying out a pair of spur gears, it is also true that following the correct procedure can make the task much easier. You cannot install bevel gears in the same manner as spur and helical gears and expect them to behave and perform as well; to optimize the performance of any two bevel gears, the gears must be positioned together so that they run smoothly without binding and/or excessive backlash.

47 Liebherr Touts Technology at Latest Gear Seminar (June/July 2013)

For two days in Saline, Michigan, Liebherr's clients, customers and friends came together to discuss the latest gear products and technology. Peter Wiedemann, president of Liebherr Gear Technology Inc., along with Dr.-Ing. Alois Mundt, managing director, Dr.-Ing. Oliver Winkel, head of application technology, and Dr.-Ing. Andreas Mehr, technology development shaping and grinding, hosted a variety of informative presentations.

48 Need a Snack - Try 3D Printing Technology (June/July 2013)

3-D printing offers a new way to create food, even gear-shaped snacks are now available via this new technology.

49 Leading the Way in Lead Crown Correction and Inspection (August 2013)

Forest City Gear applies advanced gear shaping and inspection technologies to help solve difficult lead crown correction challenges half a world away. But these solutions can also benefit customers much closer to home, the company says. Here's how…

50 Gear Expo 2013 - An Oscar-Worthy Indy Production (August 2013)

We are well into an odd-number year, so it must be just about time for another Gear Expo. Indeed, the big show -- Gear Expo 2013 -- kicks off in Indianapolis at 9:00 a.m. Tuesday, September 17, wrapping up Thursday the 19th at 4:00 p.m. And whether you are exhibiting or attending, the bottom line is you are going -- a good thing for you, your company and the tightly knit U.S. gear industry.

51 Untraditional Gear Machining (October 2013)

Look beyond the obvious, and you may well find a better way to machine a part, and serve your customer better. That’s the lesson illustrated in a gear machining application at Allied Specialty Precision Inc. (ASPI), located in Mishawaka, Indiana.

52 Heat Treat Suppliers Focused on Gears (August 2013)

Heat treat suppliers look to the gear industry and the upcoming combined Gear Expo/Heat Treat 2013 for new business.

53 Industry News (May 2013)

The complete Industry News section from the May 2013 issue of Gear Technology

54 Design of a Flexible and Lean Machining Cell, Part II (August 2013)

Job shops may be ill-advised to undertake a complete reorganization into FLEAN (Flexible and Lean) cells. A FLEAN cell would (i) be flex-ible enough to produce any and all orders for parts that belong in a specific part family and (ii) utilize lean to the maximum extent possible to eliminate waste.

55 Industry News (August 2013)

The complete Industry News section from the August 2013 issue of Gear Technology.

56 Magnetic Gearing Attracting More Followers (August 2013)

"Going green" and energy efficiency are goals that all industries -- especially in Europe and the United States -- are working on, in such sectors as electric motors, lubrication, gears and on and on. Drumroll here please for magnetic gearing

57 Going to Gear Expo (September 2013)

Like many of you in the gear industry, we’ve been working extremely hard over the past few months getting ready for Gear Expo 2013, which takes place September 17-19 in Indianapolis.

58 Letters to the Editor (September 2013)

Readers respond to our "Job Shop Lean" column and the "My Gear is Bigger than Your Gear" article.

59 Product News (September 2013)

The complete Product News section from the September 2013 issue of Gear Technology.

60 Siemens Has Georgia Schools on its Mind (September 2013)

Siemens is helping the state of Georgia's STEM initiative by helping develop educational programs for the public schools.

61 New-Formula Acetylene Cool for Heat Treatment (September 2013)

Acetylene with DMF solvent enables benefits of low-pressure vacuum carburizing.

62 Product News (October 2013)

The complete Product News section from the October 2013 issue of Gear Technology.

63 Engineering Questions - SME has the Answers with Knowledge Edge (August 2013)

The Society of Manufacturing Engineers (SME) has been gathering, validating and sharing manufacturing knowledge for more than 80 years. Traditionally, SME resources were purchased by individuals for their own personal use or by colleges and universities as textbooks. Recently, these same colleges and universities were looking for digital resources to provide to their instructors and students. Companies were requesting SME content digitally for their employees as well.

64 If You Rebuild It, They Will Buy It (May 2013)

It’s been said that the best ideas are often someone else's. But with rebuilt, retrofitted, re-controlled or remanufactured machine tools, buyer beware and hold onto your wallet. Sourcing re-work vendors and their services can require just as much homework, if not necessarily dollars, as with just-off-the-showroom-floor machines.

65 Operating Pressure Angle (May 2013)

What is the difference between pressure angle and operating pressure angle?

66 Gear Material Selection and Construction for Large Gears (January/February 2013)

A road map is presented listing critical considerations and optimal use of materials and methods in the construction of large gears.

67 Balancing: Smoke and Mirrors No Longer (January/February 2013)

By virtue of collected anecdotal accounts, equations and problem solving, balancing is discussed as more math and common sense, and less smoke and mirrors.

68 Measurement of Involute Master (January/February 2013)

Our experts tackle the topic of measuring involute masters, including both master gears and gear inspection artifacts.

69 My Gear Is Bigger than Your Gear (March/April 2013)

Industry battles it out for World's Largest Gear title.

70 Do No Destructive Testing (January/February 2013)

An overview of nondestructive testing and its importance in the manufacture of big gears.

71 Workholding Options (March/April 2013)

Question: We manufacture some gears that require an axial face as a datum, as well as locating on the bore for centering. Other gears use only the bore for both axial and radial locating. What type of workholding is appropriate for each type of part? Is there workholding that will work for both types?

72 Producing Large-Sized, Skew Bevel Gear Pinion Using Multi-Axis Control and Multi-Tasking Machine Tool (March/April 2013)

This paper proposes a method for the manufacture of a replacement pinion for an existing, large-sized skew bevel gear using multi-axis control and multitasking machine tool.

73 Lean Shipping - Job Shop Lean (March/April 2013)

The shipping department is the closest to the customer, and its main objective is to maximize shipped orders every month. Our lean guru shows how to eliminate waste in the shipping department.

74 Recent Inventions and Innovations in Induction Hardening of Gears and Gear-Like Components (March/April 2013)

This paper examines the expanding capabilities of induction hardening of gears through methods like spin hardening or tooth-by-tooth techniques.

75 How to Conduct a Heat Treat Audit (March/April 2013)

Audits of the heat treating department are a vital part of any good quality program - either as part of a self-assessment or ISO program for a captive shop or - of equal importance - as part of an evaluation of the capabilities of a commercial heat treat supplier. In either case, the audit process needs to be formal in nature and follow specific guidelines.

76 The Halls of Ivy Tech Are Humming with Precision Tooling (October 2013)

If you've been following this space with any regularity, you know that grassroots efforts among industry and academia are springing up around the country to help win the hearts, minds and talents of young people in nudging them towards a career in manufacturing. Add another partnership to the list.

77 The Gear Gods Help Those That Help Themselves (January/February 2013)

"Gear Train" is a new Gear Technology section focusing on training and education in the gear industry. For the first installment, we've focused on AGMA's online and video training programs.

78 Industry News (March/April 2013)

The complete Industry News section from the March/April 2013 issue of Gear Technology.

79 Job Shop Lean - Assembly (May 2013)

The Tiger Team from Hoerbiger looks for ways to cut waste and improve throughput in the company's assembly cell.

80 How Gear Hobbing Works (March/April 2013)

Hobbing is one of the most fundamental processes in gear manufacturing. Its productivity and versatility make hobbing the gear manufacturing method of choice for a majority of spur and helical gears.

81 Industry News (January/February 2013)

The complete Industry News section from the January/February 2013 issue of Gear Technology.

82 Coordinating Efforts (May 2013)

Like many Americans, I've been trained with the idea that those who see a problem should be the ones responsible for helping to solve it. If you see that something is broken, and you know how to fix it, don't wait for your dad, your boss or the government to tell you what to do. Just fix it.

83 Liebherr LFG Grinding Machine (May 2013)

This machine concept facilitates highly productive profile grinding for large workpieces. The range for external and internal gears comprises models for manufacturing workpieces up to 2,000 millimeters – for industrial gear units, wind power, and marine propulsion applications

84 Product News (March/April 2013)

The complete Product News section from the March/April 2013 issue of Gear Technology.

85 Job Shop Lean (January/February 2013)

This is the first article in an eight-part "reality" series on implementing continuous improvement at Hoerbiger Corporation. Throughout 2013, Dr. Shahrukh Irani will report on his progress applying the job shop lean strategies he developed during his time at Ohio State University.

86 Heavy-Duty Demands - Modern Coating Technology Examined (May 2013)

The hob is a perfect example of how a little manufacturing ingenuity can make a reliable, highly productive cutting tool. It's an engineering specimen that creates higher cutting speeds, better wear resistance and increases rigidity. The cutting tool alone, however, can't take all the credit for its resourcefulness. Advanced coating technology from companies like Sulzer, Oerlikon Balzers, Ionbond, Seco Tools and Cemecon helps improve cutting tools by reducing overall costs, increasing tool life and maintaining the highest levels of productivity. The following is a quick recap of new technologies and the latest information in the coating market.

87 Product News (January/February 2013)

The complete Product News section from the January/February 2013 issue of Gear Technology.

88 DFM Crucial for Gear Industry Success (March/April 2013)

"Design for manufacturability" (DFM) is a well-established practice, essential to realizing the successful transformation of concepts into mass-produced gears and motion control devices. And yet, all too often issues that could have been avoided are identified very late in the process that impact production costs and schedules. This suggests that key DFM principles are often underutilized in practice and are not applied consistently - or to the degree necessary - to avoid these negative results.

89 Reinventing Cutting Tool Production at Gleason (May 2013)

Investment in advanced new manufacturing technologies is helping to reinvent production processes for bevel gear cutters and coarse-pitch hobs at Gleason - delivering significant benefits downstream to customers seeking shorter deliveries, longer tool life and better results.

90 Delivering Big Gears Fast (May 2013)

When a customer needed gears delivered in three weeks, here’s how Brevini Wind got it done.

91 Events (June 2009)

PowderMet 2009, plus the full technical calendar for Gear Technology's June 2009 issue.

92 Brad Foote and 3M Collaborate on Testing of Ground Parts (March/April 2014)

Cubitron II wheels are put to the test in this case study.

93 Computer-Aided Finite Capacity Scheduling of a FLEAN Machining Cell (October 2013)

A look at some of the software options available to help with lean scheduling in a job shop

94 Making it in Mobile (November/December 2014)

"If it's broken, bring it on in." That's the advice offered by Roy Parker, president and owner of Jones Welding Company Inc.

95 The Influence of Tool Tolerances on the Gear Quality of a Gear Manufactured by an Indexable Insert Hob (July 2014)

Recently, a new type of hob with carbide inserts has been introduced, providing higher cutting speeds, longer tool life and higher feed rates when compared to re-grindable, high-speed steel hobs. But with this kind of hob, new challenges occur due to positional errors of the cutting edges when mounted on the tool. These errors lead to manufacturing errors on the gear teeth which must be controlled. In this paper, the tooth quality of a gear manufactured by hobs with different quality classes is analyzed using a simulation model in combination with Monte Carlo methods.

96 Innovative Induction Hardening Process with Pre-heating for Improved Fatigue Performance of Gear Component (July 2014)

Contact fatigue and bending fatigue are two main failure modes of steel gears, while surface pitting and spalling are two common contact fatigue failures -- caused by alternating subsurface shear stresses from the contact load between two gear mates. And when a gear is in service under cyclic load, concentrated bending stresses exist at the root fillet -- the main driver of bending fatigue failures. Induction hardening is becoming an increasingly popular response to these problems, due to its process consistency, reduced energy consumption, clean environment and improved product quality -- but not without issues of its own (irregular residual stresses and bending fatigue). Thus a new approach is proposed here that flexibly controls the magnitude of residual stress in the regions of root fillet and tooth flank by pre-heating prior to induction hardening. Using an external spur gear made of AISI 4340 as an example, this new concept/process is demonstrated using finite element modeling and DANTE commercial software.

97 Industry News (July 2014)

The complete Industry News section from the July 2014 issue of Gear Technology.

98 Honing of Gears (August 2014)

The honing of gears - by definition - facilitates ease of operation, low noise and smoother performance in a transmission. Honing also contributes to reduced friction in the powertrain. Both the intense cutting (roughing process) as well as the functionally fine- finishing of transmission gears can be performed in one setup, on one machine.

99 The Pros and Cons of Fully Ground Root Fillets (August 2014)

For maximum life in carburized and ground gearing, I have been advised that fully grinding a radius into the root gives maximum resistance against fatigue failures. Others have advised that a hobbed and unground radius root form is best. Which is best, and why?

100 Setting Load Parameters for Viable Fatigue Testing of Gears in Powertrain Axles Part I: Single-Reduction Axles (August 2014)

This presentation introduces a new procedure that - derived from exact calculations - aids in determining the parameters of the validation testing of spiral bevel and hypoid gears in single-reduction axles.

101 Industry News (August 2014)

The complete Industry News section from the August 2014 issue of Gear Technology.

102 Cracking the WIP (September/October 2014)

Over the past few months I've talked with several different gear manufacturers who are in the process of upgrading their gear making equipment with modern CNC machine tools. Each of these manufacturers has come to the realization that in order to stay competitive, he needs to streamline operations and become more efficient...

103 Product News (September/October 2014)

The complete product news section from the September / October 2014 Issue Gear Technology.

104 Micropitting of Large Gearboxes: Influence of Geometry and Operating Conditions (September/October 2014)

The focus of the following presentation is two-fold: 1) on tests of new geometric variants; and 2) on to-date, non-investigated operating (environmental) conditions. By variation of non-investigated eometric parameters and operation conditions the understanding of micropitting formation is improved. Thereby it is essential to ensure existent calculation methods and match them to results of the comparison between large gearbox tests and standard gearbox test runs to allow a safe forecast of wear due to micropitting in the future.

105 Simulation of Deviations in Hobbing and Generation Grinding (September/October 2014)

The hobbing and generation grinding production processes are complex due to tool geometry and kinematics. Expert knowledge and extensive testing are required for a clear attribution of cause to work piece deviations. A newly developed software tool now makes it possible to simulate the cutting procedure of the tool and superimpose systematic deviations on it. The performance of the simulation software is illustrated here with practical examples. The new simulation tool allows the user to accurately predict the effect of errors. With this knowledge, the user can design and operate optimal, robust gearing processes.

106 Industry News (November/December 2014)

The complete Industry News section from the November/December 2014 issue.

107 No Compromising on Quality at Allison Transmission (July 2014)

Gleason 350GMS helps put higher quality, more reliable gears into its next-generation TC10 automatic transmission.

108 Buyers Guide Category Listing (November/December 2014)

Industry Buyers Guide

109 Keeping it in the Family (November/December 2014)

In this online-only exclusive, we present a profile of Jones Welding Company.

110 On the Cutting Edge (January/February 2015)

Sentences that start off with some variance of “I don’t want to brag, but…” are generally a good indicator that it’s precisely what the speaker intends to do and typically end with bold proclamations that are immediately and eminently quotable — the kind of quotes perfect for beginning a feature story with an eye-catching artistic flourish.

111 Getting in Gear with the Chain of Innovations (January/February 2015)

At the dawn of the Industrial Revolution, so-called mechanics were tasked with devising the precise methods that would make mass production possible. The result was the first generation of machine tools, which in turn required improved tooling and production methods.

112 On the Correlation of Specific Film Thickness and Gear Pitting Life (January/February 2015)

The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness defined as the ratio of lubricant film thickness to the composite surface roughness. It can be difficult to combine results of studies to create a cohesive and comprehensive data set. In this work gear surface fatigue lives for a wide range of specific film values were studied using tests done with common rigs, speeds, lubricant temperatures, and test procedures.

113 Quality and Surface of Gears Manufactured by Free-Form Milling with Standard Tools (January/February 2015)

The recently available capability for the free-form milling of gears of various gear types and sizes — all within one manufacturing system — is becoming increasingly recognized as a flexible machining process for gears.

114 Industry News (January/February 2015)

News from around the Gear Industry

115 GT Extras (March/April 2015)

This issue, GT Extras brings you "Heat Treat and Induction Hardening of Industrial Gears," a treasure trove of heat treating related technical articles and a call for help in preparation for AGMA's 100th anniversary.

116 Erosion of Knowledge (March/April 2015)

Have you ever stood on a beach at the edge of the water and felt the grains of sand dissolve from under your feet as the water recedes? No matter how hard you plant your feet or grip your toes, you can’t hold on to the sand. It just flows away right from under you. In many ways that sand is like the knowledge and experience of our graying manufacturing workforce. It seems inevitable that much of that knowledge is being washed away.

117 Product News (March/April 2015)

The complete Product News section from the March/April 2015 issue of Gear Technology.

118 Solving the Forgings Paradox (March/April 2015)

The process of forging metal into shapes possesses a surprisingly long and storied history. For example, the method of hot rolling can trace its protracted existence all the way back to an enigmatic Italian polymath named Leonardo da Vinci (you may have heard of him), who reportedly invented the rolling mill one lazy day in the 1400s.

119 Gear Industry Heat Treat Resource Guide (July 2014)

Heat treating is one of the most critical operations in the manufacture of quality gears. Everything can be done to perfection, but if the heat treating isn’t right, all of your hard work and efforts are wasted. We know how important it is for gear manufacturers to find the right heat treating service provider. That’s why we’ve compiled this Heat Treat Resource Guide -- the only directory of heat treat service providers that’s specific to the gear industry. The companies listed here are all interested in working with gear manufacturers, and many of them have specialties and capabilities that are uniquely suited to the types of products you manufacture.

120 Machine Marks on Gear Flanks (May 2014)

What causes shaving cutter marks on gear flanks and can they be prevented?

121 Purchasing Gear Lubricants - Be Careful When Playing the Numbers Game (October 2013)

When it comes to purchasing gear lubricants, many people on both the sales and purchasing side decide to play the numbers game. The person with the most numbers, or the biggest numbers, or the lowest numbers, must have the best product - right? Wrong; gear oil selection is not a game, and numbers alone cannot determine the right product for an application.

122 Industry News (January/February 2014)

The complete Industry News section from the January/February 2014 issue of Gear Technology.

123 Industry News (October 2013)

The complete Industry News section from the October 2013 issue of Gear Technology.

124 VIPS - Very Important Products and Services (November/December 2013)

Very important gear industry suppliers are featured here.

125 Lean Resources (November/December 2013)

The final installment of our Job Shop Lean series includes a wide variety of educational resources to help you continue your own lean journey.

126 High Temperature Gear Materials (November/December 2013)

What gear material is suitable for high-temperature (350 – 550 degree C), high-vacuum, clean-environment use?

127 Product News (January/February 2014)

The complete Product News section from the January/February 2014 issue of Gear Technology.

128 Super-Sized Quality Control (January/February 2014)

It's not easy being big. Maybe that's not exactly how the phrase goes, but it's applicable, particularly when discussing the quality requirements of large gears. The size alone promises unique engineering challenges. BONUS Online Exclusive: Big or Small - Inspection is Key to Success.

129 Learn to Work, Work to Earn (January/February 2014)

Apprenticeship programs are back in the USA - sort of.

130 The Sales Pitch (January/February 2014)

Kaukauna, Wisconsin may hold the secrets to solving the problem of our skilled labor shortage.

131 Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part I (January/February 2014)

Part I of this paper describes the theory behind double-flank composite inspection, detailing the apparatus used, the various measurements that can be achieved using it, the calculations involved and their interpretation. Part II, which will appear in the next issue, includes a discussion of the practical application of double-flank composite inspection, especially for large-volume operations. Part II covers statistical techniques that can be used in conjunction with double-flank composite inspection, as well as an in-depth analysis of gage R&R for this technique.

132 Power Skiving of Cylindrical Gears on Different Machine Platforms (January/February 2014)

It has long been known that the skiving process for machining internal gears is multiple times faster than shaping, and more flexible than broaching, due to skiving's continuous chip removal capability. However, skiving has always presented a challenge to machines and tools. With the relatively low dynamic stiffness in the gear trains of mechanical machines, as well as the fast wear of uncoated cutters, skiving of cylindrical gears never achieved acceptance in shaping or hobbing, until recently.

133 The XL Gears Project (January/February 2014)

Much of the existing guidelines for making large, high-performance gears for wind turbine gearboxes exhibit a need for improvement. Consider: the large grinding stock used to compensate for heat treatment distortion can significantly reduce manufacturing productivity; and, materials and manufacturing processes are two other promising avenues to improvement. The work presented here investigates quenchable alloy steels that, combined with specifically developed Case-hardening and heat treatment processes, exhibits reduced distortion and, in turn, requires a smaller grinding stock.

134 Gear Engineer by Day, Baritone by Night (January/February 2014)

When they’re not solving the latest mechanical engineering puzzle, the seven members of the group sINGer are busy engineering their voices to create the perfect sound. Yes, you read that correctly. Mechanical engineers do have hobbies outside of gears.

135 Application and Improvement of Face Load Factor Determination Based on AGMA 927 (May 2014)

The face load factor is one of the most important items for a gear strength calculation. Current standards propose formulae for face load factor, but they are not always appropriate. AGMA 927 proposes a simpler and quicker algorithm that doesn't require a contact analysis calculation. This paper explains how this algorithm can be applied for gear rating procedures.

136 Calculation of Tooth Root Load Carrying Capacity of Beveloid Gears (June 2014)

In this paper, two developed methods of tooth root load carrying capacity calculations for beveloid gears with parallel axes are presented, in part utilizing WZL software GearGenerator and ZaKo3D. One method calculates the tooth root load-carrying capacity in an FE-based approach. For the other, analytic formulas are employed to calculate the tooth root load-carrying capacity of beveloid gears. To conclude, both methods are applied to a test gear. The methods are compared both to each other and to other tests on beveloid gears with parallel axes in test bench trials.

137 Measuring Backlash in Bevel and Hypoid Gears (June 2014)

In this installment of Ask the Expert, Dr. Stadtfeld describes the best methods for measuring backlash in bevel gears.

138 The Next Transformation (March/April 2014)

Every so often manufacturing is jolted out of its inertia by a transformative technology – one that fundamentally changes not only the way products are made, but also the economics of the business.

139 Heat Treating Buyers Guide 1998 (March/April 1998)

Gear Technology's directory of heat treating suppliers for the gear industry.

140 In Search of a Competitive Advantage (March/April 2014)

The grinding/abrasives market is rapidly changing, thanks to new technology, more flexibility and an attempt to lower customer costs. Productivity is at an all-time high in this market, and it’s only going to improve with further R&D. By the time IMTS 2014 rolls around this September, the gear market will have lots of new toys and gadgets to offer potential customers. If you haven’t upgraded any grinding/abrasives equipment in the last five years, now might be a good time to consider the investment.

141 PPD Wear Protection Treatment for Large Parts Opens New Horizons (March/April 2014)

Environmentally friendly, highly efficient and lasting a product's lifetime. With characteristics like this, Pulsed-Plasma Diffusion (PPD) technology from Oerlikon Balzers has established itself as an industry standard for the treatment of large automotive press tooling. Now the technology specialists are targeting new applications with this advanced process, offering an alternative to traditional hard-chrome processes.

142 Hardening Technology Focuses on Dimensional Accuracy (March/April 2014)

New technology from Eldec/EMAG helps control the induction hardening process.

143 Press Quenching and Effects of Prior Thermal History on Distortion during Heat Treatment (March/April 2014)

Precision components (industrial bearing races and automotive gears) can distort during heat treatment due to effects of free or unconstrained oil quenching. However, press quenching can be used to minimize these effects. This quenching method achieves the relatively stringent geometrical requirements stipulated by industrial manufacturing specifications. As performed on a wide variety of steel alloys, this specialized quenching technique is presented here, along with a case study showing the effects of prior thermal history on the distortion that is generated during press quenching.

144 Technological Potential and Performance of Gears Ground by Dressable CBN Tools (March/April 2014)

Dressable vitrified bond CBN grinding tools combine the advantages of other common tool systems in generating gear grinding. Yet despite those technological advantages, there is only a small market distribution of these grinding tools due to high tool costs. Furthermore, scant literature exists regarding generating gear grinding with dressable CBN. This is especially true regarding the influence of the grinding tool system on manufacturing-related component properties. The research objective of this report is to determine the advantages of dressable CBN tools in generating gear grinding.

145 Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part II (March/April 2014)

Part I of this paper, which appeared in the January/February issue of Gear Technology, described the theory behind double-flank composite inspection. It detailed the apparatus used, the various measurements that can be achieved using it, the calculations involved and their interpretation. The concluding Part II presents a discussion of the practical application of double-flank composite inspection -- especially for large-volume operations. It also addresses statistical techniques that can be used in conjunction with double-flank composite inspection, as well as an in-depth analysis of gage R&R for this technique.

146 Coming Home, but to What (May 2014)

Many vets have the skills, but no place to apply them.

147 The Technology Shift (May 2014)

Decades ago, technology shifted from HSS to indexable inserts in turning and milling. This movement wasn't immediately realized in gear hobbing because coated PM-HSS hobs and complex gear profiles remained highly effective and productive methods. Only fairly recently have gear manufacturers started to take a serious look at indexable technology to cut gear teeth.

148 Progress in Gear Milling (January/February 2013)

Sandvik presents the latest in gear milling technologies.

149 IMTS 2012 Product Preview (August 2012)

Booth previews from exhibitors showing products and services for the gear industry.

150 Gear Shaving Basics - Part I (November/December 1997)

Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of gear teeth. Its purpose is to correct errors in index, helix angle, tooth profile and eccentricity. The process also improves tooth surface finish and eliminates by means of crowned tooth forms the danger of tooth end load concentrations in service.

151 Myths and Miracles of Gear Coating (July/August 1999)

Three years ago, coated gears seemed to be the perfect solution for the Micro Marine Corporation. The early designs for the gear drive of their MicroCAT human-powered boat used a combination of thin-film dry gear coatings with lubrication and wear-resistance properties. These coatings simplified their design, provided corrosion resistance, made the gear drive environmentally safe and eliminated the need for gear drive lubrication and maintenance. It was a success story in the making.

152 Dry Cutting of Bevel and Hypoid Gears (May/June 1998)

High-speed machining using carbide has been used for some decades for milling and turning operations. The intermittent character of the gear cutting process has delayed the use of carbide tools in gear manufacturing. Carbide was found at first to be too brittle for interrupted cutting actions. In the meantime, however, a number of different carbide grades were developed. The first successful studies in carbide hobbing of cylindrical gears were completed during the mid-80s, but still did not lead to a breakthrough in the use of carbide cutting tools for gear production. Since the carbide was quite expensive and the tool life was too short, a TiN-coated, high-speed steel hob was more economical than an uncoated carbide hob.

153 Introduction to ISO 6336 What Gear Manufacturers Need to Know (July/August 1998)

ISO 6336 Calculation of Load Capacity of Spur and Helical Gears was published in 1997 after 50 years of effort by an international committee of experts whose work spanned three generations of gear technology development. It was a difficult compromise between the existing national standards to get a single standard published which will be the basis for future work. Many of the compromises added complication to the 1987 edition of DIN 3990, which was the basic document.

154 The Basics of Gear Metrology and Terminology Part I (September/October 1998)

It is very common for those working in the gear manufacturing industry to have only a limited understanding of the fundamental principals of involute helicoid gear metrology, the tendency being to leave the topic to specialists in the gear lab. It is well known that quiet, reliable gears can only be made using the information gleaned from proper gear metrology.

155 Comparing Standards (September/October 1998)

One of the best ways to learn the ISO 6336 gear rating system is to recalculate the capacity of a few existing designs and to compare the ISO 6336 calculated capacity to your experience with those designs and to other rating methods. For these articles, I'll assume that you have a copy of ISO 6336, you have chosen a design for which you have manufacturing drawings and an existing gear capacity calculation according to AGMA 2001 or another method. I'll also assume that you have converted dimensions, loads, etc. into the SI system of measurement.

156 The Basics of Gear Metrology and Terminology Part II (November/December 1998)

In the last section, we discussed gear inspection; the types of errors found by single and double flank composite and analytical tests; involute geometry; the involute cam and the causes and symptoms of profile errors. In this section, we go into tooth alignment and line of contact issues including lead, helix angles, pitch, pitchline runout, testing and errors in pitch and alignment.

157 Calculating Spur and Helical Gear Capacity with ISO 6336 (November/December 1998)

This is the third article in a series exploring the new ISO 6336 gear rating standard and its methods of calculation. The opinions expressed herein are htose of the author as an individual. They do not represent the opinions of any organization of which he is a member.

158 An Experimental Study on the Effect of Power Honing on Gear Surface Topography (January/February 1999)

Gear noise associated with tooth surface topography is a fundamental problem in many applications. Operations such as shaving, gear grinding and gear honing are usually used to finish the gear surface. Often, gears have to be treated by a combination of these operations, e.g. grinding and honing. This is because gear honing operations do not remove enough stock although they do create a surface lay favorable for quiet operation. See Fig. 1 for typical honing process characteristics. Gear grinding processes, on the other hand, do remove stock efficiently but create a noisy surface lay.

159 Selection of the Optimal Parameters of the Rack-Tool to Ensure the Maximum Gear Tooth Profile Accuracy (January/February 1999)

An analysis of possibilities for the selection of tool geometry parameters was made in order to reduce tooth profile errors during the grinding of gears by different methods. The selection of parameters was based on the analysis of he grid diagram of a gear and a rack. Some formulas and graphs are presented for the selection of the pressure angle, module and addendum of the rack-tool. The results from the grinding experimental gears confirm the theoretical analysis.

160 A New Approach to Heat Treating Parts Washing (March/April 1999)

New innovations in the management of hear treating parts washers and yielding powerful, unexpected benefits. Simply, cost effective shop floor practices are being combined in new ways to deliver big quality improvements and significant help to the bottom line. Employing these steps early in the process can dramatically cut waste hauling expenses and greatly reduce environmental liabilities while continuously producing cleaner parts.

161 Cutting Tools Roundup (May/June 1999)

The cutting tool industry has undergone some serious changes in the last couple of years in both technology and the way the industry does business. The emerging technology today, as well as for the foreseeable future, is dry cutting, especially in high volume production settings. Wet cutting continues to be as popular as ever with lubrication advances making it more economical and environmentally friendly. There has also developed a process called "near dry cutting." this process offers many of the benefits of fluids while eliminating many of hte associated problems.

162 Development of Gear Technology and Theory of Gearing (July/August 1999)

I must admit that after thumbing through the pages of this relatively compact volume (113 pages, 8.5 x 11 format), I read its three chapters(theory of gearing, geometry and technology, and biographical history) from rear to front. It will become obvious later in this discussion why I encourage most gear engineers to adopt this same reading sequence!

163 Gear Grinding With Dish Wheels (September/October 1999)

The grinding of gears with dish wheels (Maad type grinding machines) is widely viewed as the most precise method of gear grinding because of the very short and simple kinematic links between the gear and the tool, and also because the cutting edges of the wheels represent planar surfaces. However, in this grinding method, depending on the parameters of the gears and one of the adjustments (such as the number of teeth encompassed by the grinding wheels), so-called overtravel at the tip or at the root of the teeth being ground generally occurs. When this happens, machining with only one wheel takes place. As a result, the profile error and the length of the generating path increases while productivity decreases.

164 Hobs & Form Relived Cutters: Common Sharpening Problems (May/June 1998)

Fig. 1 shows the effects of positive and negative rake on finished gear teeth. Incorrect positive rake (A) increase the depth and decreases the pressure angle on the hob tooth. The resulting gear tooth is thick at the top and thin at the bottom. Incorrect negative rake (B) decreases the depth and increases the pressure angle. This results in a cutting drag and makes the gear tooth thin at the top and thick at the bottom.

165 Cast Iron: A Solid choice for Reducing Gear Noise (September/October 1999)

Material selection can play an important role in the constant battle to reduce gear noise. Specifying tighter dimensional tolerances or redesigning the gear are the most common approaches design engineers take to minimize noise, but either approach can add cost to the finished part and strain the relationship between the machine shop and the end user. A third, but often overlooked, alternative is to use a material that has high noise damping capabilities. One such material is cast iron.

166 Hard Gear Finishing with a Geometrically Defined Cutting Edge (November/December 1999)

The market demand for gear manufacturers to transmit higher torques via smaller-sized gear units inevitably leads to the use of case-hardened gears with high manufacturing and surface quality. In order to generate high part quality, there is an increasing trend towards the elimination of the process-induced distortion that occurs during heat treatment by means of subsequent hard finishing.

167 Coordinate Measuring Machines and the Gear Industry (November/December 1999)

Gears are extremely complex shapes. Coordinate measuring machines, or CMMs, are designed to measure complex shapes. It seems to follow that CMMs world, therefore, be the ideal tool for measuring gears. But the answer is not so simple.

168 Ferritic Nitrocarburizing Gears to Increase Wear Resistance and Reduce Distortion (March/April 2000)

Quality gear manufacturing depends on controlled tolerances and geometry. As a result, ferritic nitrocarburizing has become the heat treat process of choice for many gear manufacturers. The primary reasons for this are: 1. The process is performed at low temperatures, i.e. less than critical. 2. the quench methods increase fatigue strength by up to 125% without distorting. Ferritic nitrocarburizing is used in place of carburizing with conventional and induction hardening. 3. It establishes gradient base hardnesses, i.e. eliminates eggshell on TiN, TiAIN, CrC, etc. In addition, the process can also be applied to hobs, broaches, drills, and other cutting tools.

169 Reducing Production Costs in Cylindrical Gear Hobbing and Shaping (March/April 2000)

Increased productivity in roughing operations for gear cutting depends mainly on lower production costs in the hobbing process. In addition, certain gears can be manufactured by shaping, which also needs to be taken into account in the search for a more cost-effective form of production.

170 The Effect of Material Defects on Gear Perfomance - A Case Study (March/April 2000)

The quality of the material used for highly loaded critical gears is of primary importance in the achievement of their full potential. Unfortunately, the role which material defects play is not clearly understood by many gear designers. The mechanism by which failures occur due to material defects is often circuitous and not readily apparent. In general, however, failures associated with material defects show characteristics that point to the source of the underlying problem, the mechanism by which the failure initiated, and the manner in which it progressed to failure of the component.

171 Microsecond Heat Treatment of Gears (March/April 2000)

The performance of metal surfaces can be dramatically enhanced by the thermal process of rapid surface melting and re-solidification (RMRS). When the surface of a metal part (for instance, a gear) is melted and re-solidified in less than one thousandth of a second, the resulting changes in the material can lead to: Increased wear and corrosion resistance, Improved surface finish and appearance, Enhanced surface uniformity and purity, and Sealing of surface cracks and pores.

172 Gear Heat Treating by Induction (March/April 2000)

The induction hardening and tempering of gears and critical components is traditionally a hot subject in heat treating. In recent years, gear manufacturers have increased their knowledge in this technology for quality gears.

173 Geoffrey Parrish, Carburizing: Microstructures and Properties, 2nd ed., ASM, 1999, 247 pages. (May/June 2000)

Geoffrey Parrish has updated and expanded his previous book: The Influence of Microstructure on the Properties of Case-Carburized Components. It now contains at least twice the material. References and bibliography include 449 citations.

174 A Practical Guide for Molding Better Plastic Geared Transmissions (May/June 2000)

Plastic gears and transmissions require a different design approach than metal transmissions. Different tools are available to the plastic transmission designer for optimizing his geared product, and different requirements exist for inspection and testing. This paper will present some of the new technology available to the plastic gear user, including design, mold construction, inspection, and testing of plastic gears and transmissions.

175 The Design and Testing of a Low Noise Marine Gear (May/June 2000)

This article offers an overview of the practical design of a naval gear for combined diesel or gas turbine propulsion (CODOG type). The vibration performance of the gear is tested in a back-to-back test. The gear presented is a low noise design for the Royal Dutch Navy's LCF Frigate. The design aspects for low noise operation were incorporated into the overall gear system design. Therefore, special attention was paid to all the parameters that could influence the noise and vibration performance of the gearbox. These design aspects, such as tooth corrections, tooth loading, gear layout, balance, lubrication and resilient mounting, will be discussed.

176 A Modular Approach to Computing Spiral Bevel Gears and Curvic Couplings (May/June 2000)

In general, bevel gears and curvic couplings are completely different elements. Bevel gears rotate on nonintersecting axis with a ratio based on the number of teeth. Curvic couplings work like a clutch (Fig. 1).

177 Relationship Between Wear and Pitting Phenomena in Worm Gears (May/June 1998)

Worm gears display unique behavior of surfaces because of the presence of wear phenomena in addition to contact pressure phenomena.

178 Hard Gear Finishing With CBN-Basic Considerations (May/June 1998)

For over 50 years, grinding has been an accepted method of choice for improving the quality of gears and other parts by correcting heat treat distortions. Gears with quality levels better than AGMA 10-11 or DIN 6-7 are hard finished, usually by grinding. Other applications for grinding include, but are not limited to, internal/external and spur/helical gear and spline forms, radius forms, threads and serrations, compressor rotors, gerotors, ball screw tracks, worms, linear ball tracks, rotary pistons, vane pump rotators, vane slots, and pump spindles.

179 Precision Finish Hobbing (July/August 2000)

Nowadays, finish hobbing (which means that there is no post-hobbing gear finishing operation) is capable of producing higher quality gears and is growing in popularity.

180 Basic Honing & Advanced Free-Form Honing (July/August 1997)

Rotary gear honing is a crossed-axis, fine, hard finishing process that uses pressure and abrasive honing tools to remove material along the tooth flanks in order to improve the surface finish (.1-.3 um or 4-12u"Ra), to remove nicks and burrs and to change or correct the tooth geometry. Ultimately, the end results are quieter, stronger and longer lasting gears.

181 Spreading The Word (March/April 1997)

Long-time readers of these pages will know that I have always felt strongly about the subject of professional education. There's nothing more important for an individual's career development than keeping up with current technology. likewise, there's nothing more important that a company can do for itself and it employees than seeing to it they have the professional education they need. Giving people the educational tools they need to do their jobs is a necessary ingredient for success.

182 New Approaches to Nitriding (March/April 1997)

The process of nitriding has been used to case harden gears for years, but the science and technology of the process have not remained stagnant. New approaches have been developed which are definitely of interest to the gear designer. These include both new materials and new processing techniques.

183 Inreasing Hardness Through Cryogenics (March/April 1997)

The Instrumented Factory for Gears (INFAC) conducted a metallurgical experiment that examined the effects of carburizing process variables and types of cryogenic treatments in modifying the microstructure of the material. The initial experiment was designed so that, following the carburizing cycles, the same test coupons could be used in future experiment.

184 The Broaching of Gears (March/April 1997)

Broaching is a process in which a cutting tool passes over or through a part piece to produce a desired form. A broach removes part material with a series of teeth, each one removing a specified amount of stock.

185 Induction Heat Trating: Things Remembered, Things Forgotten (March/April 1997)

Many potential problems are not apparent when using new induction heat treating systems. The operator has been trained properly, and setup parameters are already developed. Everything is fresh in one's mind. But as the equipment ages, personnel changes or new parts are required to be processed on the old equipment ages, personnel changes or new parts are required to b processed on the old equipment, important information can get lost in the shuffle.

186 Dry Hobbing: Another Point of View (March/April 1997)

I would like to comment on David Arnesen's article, "Dry Hobbing Saves Automaker Money, Improves Gear Quality," in the Nov/Dec, 1996 issue.

187 Eddy Current Examination of Gear Systems (May/June 1997)

Nondestructive examination (NDE) of ferrous and nonferrous materials has long proved an effective maintenance and anomaly characterization tool for many industries. Recent research has expanded its applicability to include the inspection of large, open gear drives. Difficulties inherent in other NDE methods make them time-consuming and labor-intensive. They also present the user with the environmental problem of the disposal of used oil. The eddy current method addresses these problems.

188 Kish Method for Dermination of Hunting Mesh (May/June 1997)

When designing a gear set, engineers usually want the teeth of the gear (Ng) and the pinion (Np) in a "hunting" mesh. Such a mesh or combination is defined as one in which the pinion and the gear do not have any common divisor by a prime number. If a mesh is "hunting," then the pinion must make Np x Ng revolutions before the same pinion tooth meshes with the same gear space. It is often easy to determine if a mesh is hunting by first determining if both the pinion and the gear teeth are divisible by 2,3,5,7,etc. (prime numbers). However, in this age of computerization, how does one program the computer to check for hunting teeth? A simple algorithm is shown below.

189 Profile Grinding Gears From The Solid - Is It Practical (May/June 1997)

It isn't for everyone, but... Within the installed base of modern CNC gear profile grinding machines (approximately 542 machines worldwide), grinding from the solid isn't frequent, but a growing number of gear profile grinder users are applying it successfully using CBN-plated wheels.

190 CNC Gear Grinding Methods (May/June 1997)

Grinding in one form or another has been used for more than 50 years to correct distortions in gears caused by the high temperatures and quenching techniques associated with hardening. Grinding improves the lead, involute and spacing characteristics. This makes the gear capable of carrying the high loads and running at the high pitch line velocities required by today's most demanding applications. Gears that must meet or exceed the accuracy requirements specified by AGMA Quality 10-11 or DIN Class 6-7 must be ground or hard finished after hear treatment.

191 Eliot K. Buckingham (July/August 1997)

His resume reads like that of many gear engineers of his generation: the stint in the army during World War II; the break for college in the late 40s; deliberately vague descriptions of projects for the Air Force in the New Mexico desert in the early 50s; the corporate engineering jobs later on in the decade.

192 The Gear Standards Challenge (September/October 1997)

Who wants or needs technical details about gearing? Who cares about it? Three out of every four people who are reading this magazine make up at least 75% of those who have an interest in the subject. The members of AGMA, EUROTRANS, JGMA and JSIM have an interest. All the people attending the Gear Expo in Detroit have an interest. Clearly, however, the people with the most pressing interest in our industry are our customers, the end users of gear products. The unfortunate reality, though, is that in many cases, these customers don't even know that's what they want.

193 AGMA and ISO Accuracy Standards (May/June 1998)

The American Gear Manufacturers Association (AGMA) is accredited by the American National Standards Institute (ANSI) to write all U.S. standards on gearing. However, in response to the growing interest in a global marketplace, AGMA became involved with the International Standards Organization (ISO) several years ago, first as an observer in the late 1970s and then as a participant, starting in the early 1980s. In 1993, AGMA became Secretariat (or administrator) for Technical Committee 60 of ISO, which administers ISO gear standards development.

194 Thermal Effects on CMMs (September/October 1997)

The trend toward moving coordinate measuring machines to the shop floor to become an integral part of the manufacturing operations brings real time process control within the reach of many companies. Putting measuring machines on the shop floor, however, subjects them to harsh environmental conditions. Like any measuring system, CMMs are sensitive to any ambient condition that deviates from the "perfect" conditions of the metrology lab.

195 Looking to The Future (September/October 1997)

Economic times are good right now in America and in the gear industry. We're in the seventh year of an up cycle. The tough shake-outs of the 1980s and early 90s are over. Orders are up. Backlogs are at comfortable levels. We're looking at what promises to be the biggest, most successful trade show in the industry's history coming up in Detroit in October. The most pressing question on the immediate horizon seems to be "How long can the good times go on?"

196 Capitalizing on Your Human Capital (November/December 1997)

A fundamental characteristic of the gear industry is that it is capital intensive. In the last decade, the gear manufacturing industry has been undergoing an intense drive toward improving and modernizing its capital equipment base. The Department of Commerce reports that annual sales of gear cutting equipment have increased nearly 60% since 1990. While this effort has paid off in increased competitiveness for the American gear industry, it is important to remember that there is another capital crucial to manufacturing success - "human capital."

197 Gear Crack Propagation Investigations (November/December 1997)

A common design goal for gears in helicopter or turboprop power transmission is reduced weight. To help meet this goal, some gear designs use thin rims. Rims that are too thin, however, may lead to bending fatigue problems and cracks. The most common methods of gear design and analysis are based on standards published by the American Gear Manufacturers Association. Included in the standards are rating formulas for gear tooth bending to prevent crack initiation (Ref. 1). These standards can include the effect of rim thickness on tooth bending fatigue (Ref 2.). The standards, however, do not indicate the crack propagation path or the remaining life once a crack has started. Fracture mechanics has developed into a useful discipline for predicting strength and life of cracked structures.

198 Production Increase When Hobbing with Carbide Hobs (January/February 1998)

We are all looking for ways to increase production without sacrificing quality. One of the most cost-effective ways is by improving the substrate material of your hob. Solid carbide hobs are widely used in many applications throughout the world. LMT-Fette was the first to demonstrate the use of solid carbide hobs in 1993 on modern high-speed carbide (HSC) hobbing machines. Since then the process of dry hobbing has been continuously improving through research and product testing. Dry hobbing is proving to be successful in the gear cutting industry as sales for dry hobbing machines have steadily been rising along with the dramatic increase in sales of solid carbide hobs.

199 Beginning Gear Training (January/February 1998)

Gearing is a self-training course for teaching the basic fundamentals of gears and gearing to those totally unfamiliar with the subject.

200 Gear Teeth With Byte (January/February 1998)

Computers are everywhere. It's gotten so that it's hard to find an employee who isn't using one in the course of his or her day - whether he be CEO or salesman, engineer or machinist. Everywhere you look, you find the familiar neutral-colored boxes and bright glowing screens. And despite the gear industry's traditional reluctance to embrace new technology, more and moe of what you find on those screens are gears.

201 Programmable Separation of Runout From Profile and Lead Inspection Data for Gear Teeth With Arbitrary Modifications (March/April 1998)

A programmable algorithm is developed to separate out the effect of eccentricity (radial runout) from elemental gear inspection date, namely, profile and lead data. This algorithm can be coded in gear inspection software to detect the existence, the magnitude and the orientation of the eccentricity without making a separate runout check. A real example shows this algorithm produces good results.

202 Viewpoint (March/April 1998)

Jules Kish responds to comments about his article on finding a hunting ratio, and Dr. Sante Basili argues that shaving is still the best way to finish a rough-cut gear.

203 Choosing the Right Heat Treater (March/April 1998)

Heat treating is a critical operation in gear manufacturing. It can make or break the quality of your final product. Yet it is one that frequently gear manufacturers outsource to someone else. Then the crucial question becomes, how do you know you're getting the right heat treater? How can you guarantee your end product when you have turned over this important process to someone else?

204 New Guideless CNC Shaper for Helical Gears (March/April 1998)

Product announcements so often trumpet minor, incremental advances with works like "revolutionary" and "unique" that even the best thesaurus can fail to offer a fresh alternative to alert the reader when something really innovative and important is introduced. In the case of Mitsubishi's new CNC gear shaper, the ST25CNC, both terms apply.

205 Fahrenheit 451: Gear Up For Induction Hardening (March/April 1998)

So, you've been assigned the task to buy an induction heating system for heat treating: It's an intimidating, but by no means impossible, assignment. With the help of the information in this article, you could be able to develop common ground with your supplier and have the tools to work with him or her to get the right machine for your jobs.

206 Gear Measurement Traceability and Uncertainty (July/August 2000)

Until recently, there was a void in the quality control of gear manufacturing in this country (Ref. 1). Gear measurements were not traceable to the international standard of length through the National Institute of Standards and Technology (NIST). The U.S. military requirement for traceability was clearly specified in the military standard MIL-STD-45662A (Ref. 2). This standard has now been replaced by commercial sector standards including ISO 9001:1994 (Ref. 3), ISO/IEC Guide 25 (Ref, 4), and the U.S. equivalent of ISO/IEC Guide 25 - ANSI/NCSL Z540-2-1997 (Ref. 5). The draft replacement to ISO/IEC Guide 25 - ISO 17025 states that measurements must either be traceable to SI units or reference to a natural constant. The implications of traceability to the U.S. gear industry are significant. In order to meet the standards, gear manufacturers must either have calibrated artifacts or establish their own traceability to SI units.

207 Gear Oil Micropitting Evaluation (September/October 2000)

During the last decade, industrial gear manufacturers, particularly in Europe, began to require documentation of micropitting performance before approving a gear oil for use in their equipment. The development of micropitting resistant lubricants has been limited both by a lack of understanding of the mechanism by which certain lubricant chemistry promotes micropitting and by a lack of readily available testing for evaluation of the micropitting resistance of lubricants. This paper reports results of two types of testing: (1) the use of a roller disk machine to conduct small scale laboratory studies of the effects of individual additives and combinations of additives on micropitting and (2) a helical gear test used to study micropitting performance of formulated gear oils.

208 AGMA FTM: Where Great Minds and Manufacturing Mesh (November/December 2012)

Another year, another AGMA Fall Technical Conference. But this is no ho-hum event. Not when every year, the conference attracts some of the greatest mechanical engineering minds on the planet, along with representatives of the world’s greatest manufacturing entities. And who knows—perhaps one day there will be an extraterrestrial contingent—the science is that good. And all of it readily applicable to real-world manufacturing.

209 Sicmat Utilizes NUM CNC Systems (September 2012)

A high-performance, 11-axis CNC system from NUM has enabled machine tool manufacturer Sicmat to create a gear honing machine that sets a new industry standard for post-hardening fine finishing.

210 Heat Treat Process and Material Selection for High Performance Gears (March/April 2003)

The selection of the heat treat process and the congruent material required for high performance gears can become very involved.

211 Characterizaton of Retained Austenite in Case Carburized Gears and Its Influence on Fatigue Performance (May/June 2003)

Carburized helical gears with high retained austenite were tested for surface contact fatigue. The retained austenite before test was 60% and was associated with low hardness near the case's surface. However, the tested gears showed good pitting resistance, with fatigue strength greater than 1,380 MPa.

212 Performance of Skiving Hobs in Finishing Induction Hardened and Carburized Gears (May/June 2003)

In order to increase the load carrying capacity of hardened gears, the distortion of gear teeth caused by quenching must be removed by precision cutting (skiving) and/or grinding. In the case of large gears with large modules, skiving by a carbide hob is more economical than grinding when the highest accuracy is not required.

213 Large Scores and Radial Cracks on Case-Hardened Worms (May/June 2003)

In the last couple of years, many research projects dealt with the determination of load limits of cylindrical worm gears. These projects primarily focused on the load capacity of the worm wheel, whereas the worm was neglected. This contribution presents investigations regarding damages such as large scores and cracks on the flanks of case-hardened worms.

214 The Two-Sided-Ground Bevel Cutting Tool (May/June 2003)

In the past, the blades of universal face hobbing cutters had to be resharpened on three faces. Those three faces formed the active part of the blade. In face hobbing, the effective cutting direction changes dramatically with respect to the shank of the blade. Depending on the individual ratio, it was found that optimal conditions for the chip removal action (side rake, side relief and hook angle) could just be established by adjusting all major parameters independently. This, in turn, results automatically in the need for the grinding or resharpening of the front face and the two relief surfaces in order to control side rake, hook angle and the relief and the relief angles of the cutting and clearance side.

215 On a Possible Way of Size and Weight Reduction of a Car Transmission (July/August 2003)

Almost any external tooth form that is uniformly spaced around a center can be hobbed. Hobbing is recognized as an economical means of producing spur and helical gears with involute tooth profiles.

216 Direct Gear Design: Bending Stress Minimization (September/October 2003)

Bending stress evaluation in modern gear design is generally based on the more-than-one-hundred-year-old Lewis equation.

217 Local 3-D Flank Form Optimizations for Bevel Gears (September/October 2003)

Optimizing the running behavior of bevel and hypoid gears means improving both noise behavior and load carrying capacity. Since load deflections change the relative position of pinion and ring gear, the position of the contact pattern will depend on the torque. Different contact positions require local 3-D flank form optimizations for improving a gear set.

218 Adapting Lean for High-Mix, Low-Volume Manufacturing Facilities (August 2012)

Why traditional lean manufacturing approaches need to be adapted for job shop environments.

219 Calculating Face Load Distribution Factor (March/April 2015)

How should we consider random helix angle errors fHβ and housing machining errors when calculating KHβ? What is a reasonable approach?

220 Case Study Involving Surface Durability and Improved Surface Finish (August 2012)

Gear tooth wear and micropitting are very difficult phenomena to predict analytically. The failure mode of micropitting is closely correlated to the lambda ratio. Micropitting can be the limiting design parameter for long-term durability. Also, the failure mode of micropitting can progress to wear or macropitting, and then go on to manifest more severe failure modes, such as bending. The results of a gearbox test and manufacturing process development program will be presented to evaluate super-finishing and its impact on micropitting.

221 IMTS 2012 Product Preview (September 2012)

Previews of manufacturing technology related to gears that will be on display at IMTS 2012.

222 Gear Damage Detection Using Oil Debris Analysis (January/February 2003)

The purpose of this paper was to verify, when using an oil debris sensor, that accumulated mass predicts gear pitting damage and to identify a method to set threshold limits for damaged gears.

223 Refurbishing a Ball Mill ; Bevel Gear Backlash (September 2012)

Our experts comment on reverse engineering herringbone gears and contact pattern optimization.

224 How Bearing Design Improves Gearbox Performance (September 2012)

Gearbox performance, reliability, total cost of ownership (energy cost), overall impact on the environment, and anticipation of additional future regulations are top-of-mind issues in the industry. Optimization of the bearing set can significantly improve gearbox performance.

225 A Quick-Start Approach for Implementing Lean in Job Shops (October 2012)

In the August issue, we examined the lean tools that will and will not work in high-mix, low-volume manufacturing facilities. Now, we will examine how to implement the tools that will work in the job shop with an approach that expands the capabilities of value stream mapping.

226 Product News (October 2012)

The complete Product News section from the October 2012 issue of Gear Technology.

227 Gear Grinding Gets Integrated at IMTS 2012 (October 2012)

The latest machines, tooling and technology for gear grinding were featured at IMTS 2012.

228 Differential Gears (October 2012)

What are the manufacturing methods used to make bevel gears used in automotive differentials?

229 Pitting Resistance of Worm Gears: Advanced Model for Contact Pattern of Any Size, Position, Flank Type (October 2012)

An experimental and theoretical analysis of worm gear sets with contact patterns of differing sizes, position and flank type for new approaches to calculation of pitting resistance.

230 Repair of High-Value, High-Demand Spiral Bevel Gears by Superfinishing (October 2012)

Following is a report on the R&D findings regarding remediation of high-value, high-demand spiral bevel gears for the UH–60 helicopter tail rotor drivetrain. As spiral bevel gears for the UH–60 helicopter are in generally High-Demand due to the needs of new aircraft production and the overhaul and repair of aircraft returning from service, acquisition of new spiral bevel gears in support of R&D activities is very challenging. To compensate, an assessment was done of a then-emerging superfinishing method—i.e., the micromachining process (MPP)—as a potential repair technique for spiral bevel gears, as well as a way to enhance their performance and durability. The results are described in this paper.

231 Manufacturing and Pursuit of the American Dream: Reality or Fool's Quest (November/December 2012)

It wasn’t so very long ago that a high school-educated, able-bodied person with a will to work typically had little trouble finding a decent job in manufacturing. Whether at an area job shop, an OEM plant or auto plant—work was to be had. Work that paid well enough to marry, buy a home, feed, raise and educate a family—with even enough left over for a modest retirement pension.

232 If Only We Had a Crystal Ball... (November/December 2012)

Before we get into projections and prognostications about the future, let’s take a minute to review 2012. For many in the gear industry, the year was better than expected. Some manufacturers had a very successful year leading up to an even more successful manufacturing trade show (IMTS 2012). Others were searching for more business, hoping that the general state of the economy wouldn’t make things worse. In some cases, it did.

233 Predicted Scuffing Risk to Spur and Helical Gears in Commercial Vehicle Transmissions (November/December 2012)

AGMA925–A03 scuffing risk predictions for a series of spur and helical gear sets of transmissions used in commercial vehicles ranging from SAE Class 3 through Class 8.

234 Industry News (November/December 2012)

The complete Industry News section from the November/December 2012 issue of Gear Technology.

235 Wear Resistance of Plasma and Pulse Plasma Nitrided Gears (March/April 2003)

In this study, wear behavior of plasma and pulse plasma nitrided gears, made from 42CrMo4 steel, was evaluated under a lubricated sliding and pitting regime.

236 Spiral Bevel Gear Development: Elminiating Trial and Error with Computer Technology (January/February 2003)

Computer technology has touched all areas of our lives, impacting how we obtain airline tickets, purchase merchandise and receive medical advice. This transformation has had a vast influence on manufacturing as well, providing process improvements that lead to higher quality and lower costs. However, in the case of the gear industry, the critical process of tooth contact pattern development for spiral bevel gears remains relatively unchanged.

237 Evaluation of Carburized & Ground Face Gears (September/October 2000)

Designers are constantly searching for ways to reduce rotocraft drive system weight. Reduced weight can increase the payload, performance, or power density of current and future systems. One example of helicopter transmission weight reduction was initiated as part of the United States Army Advanced Rotocraft Transmission program. This example used a split-torque, face-gear configuration concept (Ref. 1). compared to a conventional design with spiral-bevel gears, the split-torque, face-gear design showed substantial weight savings benefits. Also, the use of face gears allows a wide-range of possible configurations with technical and economic benefits (Ref. 2).

238 Dry Machining for Gear Shaping (November/December 2001)

Economic production is one of the main concerns of any manufacturing facility. In recent years, cost increases and tougher statutory requirements have increasingly made cutting fluids a problematic manufacturing and cost factor in metalworking. Depending on the cutting fluid, production process and supply unit, cutting-fluid costs may account for up to 16% of workpiece cost. In some cases, they exceed tool cost by many times (Ref. 1). The response by manufacturers is to demand techniques for dry machining (Ref. 2).

239 Parallel Axis Gear Grinding: Theory & Application (November/December 2000)

The goal of gear drive design is to transit power and motion with constant angular velocity. Current trends in gear drive design require greater load carrying capacity and increased service life in smaller, quieter, more efficient gearboxes. Generally, these goals are met by specifying more accurate gears. This, combined with the availability of user-friendly CNC gear grinding equipment, has increased the use of ground gears.

240 Design Against Tooth Interior Fatigue Fracture (November/December 2000)

In a modern truck, the gear teeth are among the most stressed parts. Failure of a tooth will damage the transmission severely. Throughout the years, gear design experience has been gained and collected into standards such as DIN (Ref. 1) or AGMA (Ref. 2). Traditionally two types of failures are considered in gear design: tooth root bending fatigue, and contact fatigue. The demands for lighter and more silent transmissions have given birth to new failure types. One novel failure type, Tooth Interior Fatigue Fracture (TIFF), has previously been described by MackAldener and Olsson (Refs. 3 & 4) and is further explored in this paper.

241 Robotic Automated Deburring of Aerospace Gears (January/February 2001)

This report presents some interim results from an ongoing project being performed by INFAC, the Instrumented Factory for Gears. The purposes of this initial phase of the project were to demonstrate the feasibility of robotic automated deburring of aerospace gears, and to develop a research agenda for future work in that area.

242 The Calculation of Optimum Surface Carbon Content for Carburized Case Hardened Gears (March/April 2001)

For high-quality carburized, case hardened gears, close case carbon control is essential. While tight carbon control is possible, vies on what optimum carbon level to target can be wider than the tolerance.

243 The Submerged Induction Hardening of Gears (March/April 2001)

The tooth-by-tooth, submerged induction hardening process for gear tooth surface hardening has been successfully performed at David Brown for more than 30 years. That experience - backed up by in-depth research and development - has given David Brown engineers a much greater understanding of, and confidence in, the results obtainable from the process. Also, field experience and refinement of gear design and manufacturing procedures to accommodate the induction hardening process now ensure that gears so treated are of guaranteed quality.

244 Austempered Gears and Shafts: Tough Solutions (March/April 2001)

Austempered irons and steels offer the design engineer alternatives to conventional material/process combinations. Depending on the material and the application, austempering may provide the producers of gear and shafts with the following benefits: ease of manufacturing, increased bending and/or contact fatigue strength, better wear resistance or enhanced dampening characteristics resulting in lower noise. Austempered materials have been used to improve the performance of gears and shafts in many applications in a wide range of industries.

245 Dry Hobbing Process Technology Road Map (March/April 2001)

Recent trends in gear cutting technology have left process engineers searching for direction about which combination of cutting tool material, coating, and process technology will afford the best quality at the lowest total cost. Applying the new technologies can have associated risks that may override the potential cost savings. The many interrelated variables to be considered and evaluated tend to cloud the issue and make hobbing process development more difficult.

246 Gearbox Field Performance From a Rebuilder's Perspective (May/June 2001)

The major focus of the American Gear Manufacturers Association standards activity has been the accurate determination of a gearbox's ability to transmit a specified amount of power for a given amount of time. The need for a "level playing field" in the critical arena was one of the reasons the association was formed in the first place. Over the past 85 years, AGMA committees have spent countless hours "discussing" the best ways to calculate the rating of a gear set, often arguing vigorously over factors that varied the resulting answers by fractions of a percentage point. While all that "science" was being debated in test labs and conference rooms all over the country, out industry's customers were conducting their own experiments through the daily operation of gear-driven equipment of all types.

247 Material Properties and Performance Considerations for High-Speed Steel Gear-Cutting Tools (July/August 2001)

Users of gear-cutting tools probably do not often consciously consider the raw material from which those hobs, broaches or shavers are made. However, a rudimentary awareness of the various grades and their properties may allow tool users to improve the performance or life of their tools, or to address tool failures. The high-speed steel from which the tool is made certainly is not the only factor affecting tool performance, but as the raw material, the steel may be the first place to start.

248 What "Ease-Off" shows about Bevel and Hypoid Gears (September/October 2001)

The configuration of flank corrections on bevel gears is subject to relatively narrow restrictions. As far as the gear set is concerned, the requirement is for the greatest possible contact zone to minimize flank compression. However, sufficient reserves in tooth depth and longitudinal direction for tooth contact displacement should be present. From the machine - and particularly from the tool - point of view, there are restrictions as to the type and magnitude of crowning that can be realized. Crowning is a circular correction. Different kinds of crowning are distinguished by their direction. Length crowning, for example, is a circular (or 2nd order) material removal, starting at a reference point and extending in tooth length or face width.

249 Face Gears: An Interesting Alternative for Special Applications - Calculation, Production and Use (September/October 2001)

Crown gearings are not a new type of gear system. On the contrary, they have been in use since very early times for various tasks. Their earliest form is that of the driving sprocket, found in ancient Roman watermills or Dutch windmills. The first principles of gear geometry and simple methods of production (shaper cutting) were developed in the 1940s. In the 1950s, however, crown gears' importance declined. Their tasks were, for example, taken over by bevel gears, which were easier to manufacture and could transmit greater power. Current subject literature accordingly contains very little information on crown gears, directed mainly to pointing out their limitations (Ref. 1).

250 Properties of Tooth Surfaces due to Gear Honing with Electroplated Tools (November/December 2001)

In recent years, the demands for load capacity and fatigue life of gears constantly increased while weight and volume had to be reduced. To achieve those aims, most of today's gear wheels are heat treated so tooth surfaces will have high wear resistance. As a consequence of heat treatment, distortion unavoidably occurs. With the high geometrical accuracy and quality required for gears, a hard machining process is needed that generates favorable properties on the tooth surfaces and the near-surface material with high reliability.

251 The Alignment of High Speed Gears (January/February 2003)

This paper reviews the necessity for detailed specification, design and manufacture to achieve required performance in service. The precise definition of duty rating and a thorough understanding of the environmental conditions, whether it is in a marine or industrial application, is required to predict reliable performance of a gearbox through its service life. A case study relating to complex marine gears and other general practice is presented to review the techniques used by Allen Gears to design and develop a gearbox that integrates with the requirements of the whole machinery installation. Allen Gears has considerable experience in the design of a variety of industrial and marine gears(Ref. 1,2).

252 Net-Shape Forged Gears - The State of the Art (January/February 2002)

Traditionally, high-quality gears are cut to shape from forged blanks. Great accuracy can be obtained through shaving and grinding of tooth forms, enhancing the power capacity, life and quietness of geared power transmissions. In the 1950s, a process was developed for forging gears with teeth that requires little or no metal to be removed to achieve final geometry. The initial process development was undertaken in Germany for the manufacture of bevel gears for automobile differentials and was stimulated by the lack of available gear cutting equipment at that time. Later attention has turned to the forging of spur and helical gears, which are more difficult to form due to the radial disposition of their teeth compared with bevel gears. The main driver of these developments, in common with most component manufacturing, is cost. Forming gears rather than cutting them results in increased yield from raw material and also can increase productivity. Forging gears is therefore of greater advantage for large batch quantities, such as required by the automotive industry.

253 Atmospheric vs. Vacuum Carburizing (March/April 2002)

In recent years, improvements in the reliability of the vacuum carburizing process have allowed its benefits to be realized in high-volume, critical component manufacturing operations. The result: parts with enhanced hardness and mechanical properties.

254 Case Depth and Load Capacity of Case-Carburized Gears (March/April 2002)

Compared to non-heat-treated components, case-carburized gears are characterized by a modified strength profile in the case-hardened layer. The design of case-carburized gears is based on defined allowable stress numbers. These allowable stress numbers are valid only for a defined "optimum" case depth. Adequate heat treatment and optimum case depth guarantee maximum strength of tooth flank and tooth root.

255 Carbide Hobbing Case Study (May/June 2002)

Bodine Electric Co. of Chicago, IL., has a 97-year history of fine-and medium-pitch gear manufacturing. Like anywhere else, traditions, old systems, and structures can be beneficial, but they can also become paradigms and obstacles to further improvements. We were producing a high quality product, but our goal was to become more cost effective. Carbide hobbing is seen as a technological innovation capable of enabling a dramatic, rather than an incremental, enhancement to productivity and cost savings.

256 Gear Surface Durability Development to Enhance Transmission Power Density (July/August 2002)

Gear pitting is one of the primary failure modes of automotive transmission gear sets. Over the past years, many alternatives have been intended to improve their gear surface durability. However, due to the nature of new process development, it takes a length of time and joint efforts between the development team and suppliers to investigate and verify each new approach.

257 Performance Analysis of Hypoid Gears by Tooth Flank Form Measurement (July/August 2002)

The traditional way of controlling the quality of hypoid gears' tooth flank form is to check the tooth flank contact patterns. But it is not easy to exactly judge the tooth flank form quality by the contact pattern. In recent years, it has become possible to accurately measure the tooth flank form of hypoid gears by the point-to-point measuring method and the scanning measuring method. But the uses of measured data of the tooth flank form for hypoid gears have not yet been well developed in comparison with cylindrical involute gears. In this paper, the tooth flank form measurement of generated face-milled gears, face-hobbed gears and formulate/generated gears are reported. The authors discuss the advantages and disadvantages of scanning and point-to-point measuring of 3-D tooth flank forms of hypoid gears and introduce some examples of uses of measured data for high-quality production and performance prediction.

258 Carburizing of Big Module and Large Diameter Gears (September/October 2002)

Carburized gears have higher strengths and longer lives compared with induction-hardened or quench-tempered gears. But in big module gears, carburizing heat-treatment becomes time-consuming and expensive and sometimes cannot achieve good hardness due to the big mass-effect. Also, it is not easy to reduce distortion of gears during heat treatment.

259 The Barkhausen Noise Inspection Method for Detecting Grinding Damage in Gears (November/December 2002)

When hardened steel components are ground, there is always the possibility of damage to the steel in the form of residual stress or microstructural changes. Methods for detecting this sort of damage have always had one or more drawbacks, such as cost, time, complexity, subjectivity, or the use of hazardous chemicals.

260 Predicting the Heat-Treat Response of a Carburized Helical Gear (November/December 2002)

Using the DANTE software, a finite element simulation was developed and executed to study the response of a carburized 5120 steel helical gear to quenching in molten salt. The computer simulation included heat-up, carburization, transfer and immersion in a molten salt bath, quenching, and air cooling. The results of the simulation included carbon distribution of phases, dimensional change, hardness, and residual stress throughout the process. The predicted results were compared against measured results for hardness, dimensions and residual stress. The excellent agreement between predictions and measured values for this carburized 5120 steel gear provides a basis for assessing the various process parameters and their respective importance in the characteristics of not only these heat-treated parts, but of other compositions and shapes.

261 Engineered Gear Steels: A Review (November/December 2002)

The selection of the proper steel for a given gear application is dependent on many factors. This paper discusses the many aspects related to material, design, manufacture, and application variables. The results of several studies on the optimization of alloy design for gas- and plasma- carburization processing and reviewed.

262 Cutting Hardened Gears (November/December 2002)

The need for improved power transmissions that use gears and gearboxes with smaller overall dimensions and with lower noise generation has left manufacturing engineers searching for different methods of gear processing. This search has led to the requirement of hardened gears.

263 Experimental Characterization of Bending Fatigue Strength in Gear Teeth (January/February 2003)

The effort described in this paper addresses a desire in the gear industry to increase power densities and reduce costs of geared transmissions. To achieve these objectives, new materials and manufacturing processes, utilized in the fabrication of gears, and being evaluated. In this effort, the first priority is to compare the performance of gears fabricated using current materials and processes. However, once that priority is satisfied, it rapidly transforms to requiring accurate design data to utilize these novel materials and processes. This paper describes the effort to address one aspect of this design data requirement.

264 3-D Printing: We Ain't Seen Nothing Yet (March/April 2015)

NASA is now 3-D-printing spare parts up at the ISS (International Space Station). And in zero-gravity environments. And some of these parts are small gears and actuators, for starters. Every indication is that the list of power transmission-type parts to be converted will soon grow.

265 Local Simulation of the Specific Material Removal Rate for Generating Gear Grinding (September/October 2015)

Generating gear grinding is one of the most important finishing processes for small and medium-sized gears, its process design often determined by practical knowledge. Therefore a manufacturing simulation with the capability to calculate key values for the process — such as the specific material removal rate — is developed here. Indeed, this paper presents first results of a model for a local analysis of the value. Additionally, an empirical formula — based on a multiple regression model for a global value describing the process — is provided.

266 Measuring Residual Stress in Gears (March/April 2015)

I have heard that X-ray diffraction does not tell the whole story and that I should really run a fatigue test. I understand this may be the best way, but is there another method that gives a high degree of confidence in the residual stress measurement?

267 PentacMono-RT: High-Performance Face Milling Cutter Heads (November/December 2018)

The theory behind the latest bevel gear cutting tools is explained in detail.

268 FNA 2018 (August 2018)

Furnaces North America Exhibition Highlights Future of Heat Treating.

269 The Three Rs of Gearbox Repair: Repair, Refurbish, Replace (August 2018)

"If it ain't broke, don't fix it," goes the hoary bromide. But what if the time comes - and it most surely will - that in fact it is broke? Do you fix it or replace it? And when does gearbox maintenance and repair arrive at a point of diminishing returns and buying new is the answer?

270 Influences of the Residual Stress Condition on the Load-Carrying Capacity of Case-Hardened Gears (August 2018)

Highly loaded gears are usually casehardened to fulfill the high demands on the load-carrying capacity. Several factors, such as material, heat treatment, or macro and micro geometry, can influence the load-carrying capacity. Furthermore, the residual stress condition also significantly influences load-carrying capacity. The residual stress state results from heat treatment and can be further modified by manufacturing processes post heat treatment, e.g. grinding or shot peening.

271 Chamfering-Deburring Still a Player - Now More than Ever (September/October 2018)

Chamfering and deburring have been described as "unloved," a "necessary evil" and, in fact - "dead." After all, manual deburring is still common in many shops.

272 The Evolution of Gear Chamfering (September/October 2018)

The latest technological solutions help keep chamfering and deburring operations in-line -- often without increasing cycle times.

273 Deburring - The Underestimated Task (September/October 2018)

Deburring or chamfering of gear teeth is gaining attention in practical settings. And with a view to make the production sequence as efficient as possible, it is becoming increasingly important to be able to implement the deburring tasks directly on the cutting machine after spiral cutting.

274 Everything-Friendly Lubricants (September/October 2018)

Lubricant experts are doing more than ever to make their products less toxic and harmful to everything from the environment to the people using them — which comes with plenty of extra benefits for productivity, too!

275 Lubrication: Viscosity and Macropitting (September/October 2018)

A reader asks: Is the ISO VG 320 adequate, or should a higher viscosity grade be used? How can we stop macropitting in gear teeth?

276 Spin City (November/December 2018)

Grinding Wheel Technology Focuses on Speed, Efficiency and Time Savings

277 Why Select Gear Grinding with cBN (November/December 2018)

Cubic Boron Nitride (cBN) abrasive wheels, which are a specially engineered abrasive grain referred to as a superabrasive, typically yield 2,200 - 2,500 parts per dress with one wheel lasting as long as four to six months.

278 The Influence of a Grinding Notch on the Gear Bending Strength Rating (November/December 2018)

To achieve the requested quality, most gears today are ground. The usual grinding process includes treating the gear flank but disengaging before reaching the root rounding area. If the gear is premanufactured with a tool without protuberance, then at the position where the grinding tool retracts from the flank a grinding notch in the tooth root area is produced. Such a notch may increase the bending stresses in the root area, thus reducing the strength rating.

279 Gravy Training (January/February 2019)

We’ve just come off a very strong year for gear manufacturing, and most of you are looking forward to another good year in 2019. At least, that’s what the results of our annual State-of-the-Gear-Industry survey tell us.

280 A Comparison of Current AGMA, ISO and API Gear Rating Methods (July 2018)

There are many different gear rating methods in use today, and they can give substantially different results for any given gearset. This paper will make it easy to understand the choices and the impact the choices have on gearbox design. Eight standards are included - AGMA 2001; AGMA 6011; AGMA 6013; ISO 6336; API 613; API 617; API 672; and API 677. (Click HERE for the Appendix to this article).

281 State of the Gear Industry Special Edition (January/February 2019)

Gear industry experts give their opinions about the most important trends facing gear manufacturers today.

282 The Growth of Australian Regenerative Load Testing (January/February 2019)

Historically, gearbox original equipment manufacturers (OEMs) and repair organizations have tended to offer their customers no-load, full speed (spin) tests as a standard performance test. If a load test was specified, the supplier would probably offer a locked torque back-to-back simulated load test, which requires a large investment in tooling to connect shafts of the test and slave gearboxes.

283 Getting in Sync (January/February 2019)

Gear skiving is here to stay, and as a result of this industry shift, it’s become paramount to improve how well machining spindles synchronize with each other.

284 The Quest for the All-in-One Machine (January/February 2019)

Multitasking machines have a pretty clear sales pitch: They can do what you need them to and make a gear, but if you’re a job shop with fingers in a lot of pies, you can also use them for anything else you might need to make. Hobbing, cutting, milling, now even gear skiving; if it’s a cutting process, a multitasking machine can probably do it.

285 Beautiful on the Inside (January/February 2019)

Automotive gear manufacturers have implemented significant improvements in external planetary gear manufacturing yielding quieter gears. In addition, process stability has increased due to the post-heat treatment finishing processes employed. This article explains various complete solutions for cutting and finishing internal ring gears.

286 CNC Milling of Straight and Spiral Bevel Gears (January/February 2019)

Contrary to what appears to be popular belief, 5-axis CNC gear manufacturing is not limited to milling with end mill, ball mill or CoSIMT (Conical Side Milling Tool — it is the generic form of the Sandvik InvoMill and Gleason UpGear tools.) tools, where throughput is too low to prevent production at any significant level. Straight and spiral bevel gear manufacturing on 5-axis CNC machines using face mill cutters provides essentially the same throughput as conventional gear cutting machines — with added benefits.

287 Simulation of Spiral Bevel Gear Tooth Manufacturing to Aid in One-Piece Gear Shaft Design (January/February 2019)

In helicopter applications, the two-piece gear is typically joined by welding, bolts, or splines. In the case of the U.S. Army CH-47D Chinook helicopter, a decision was made to eliminate these joints through the use of integral design. Integral shaft spiral bevel gears must be designed such that the shaft does not interfere with gear tooth cutting and grinding. This paper discusses techniques to iterate in the design stage before manufacturing begins.

288 Industry News (January/February 2019)

The complete Industry News section from the January/February 2019 issue of Gear Technology.

289 Product News (March/April 2019)

The complete Product News section from the March/April 2019 issue of Gear Technology.

290 Moving Heat Treating In-Line (March/April 2019)

Single Piece Flow Streamlines Production for High-Volume Gear Manufacturers.

291 Trends in Induction Hardening (March/April 2019)

An Interview with Dr. Valery Rudnev, FASM, IFHTSE Fellow, Director of Science & Technology at Inductoheat, Inc.

292 Gear Nitriding 2019 (March/April 2019)

A Conversation with Sabine Kreuzmayr of RĂĽbig

293 Sensitivity Study of Press Quench Process and Concept of Tooling Design for Reduced Distortion by Modeling (July 2018)

Press quenching is designed to harden steel gears while minimizing distortion, and the process is especially applied for hardening large diameter thin-wall gears, face gears and bevel gears. The dimensional control aims at maintaining flatness, out-of-round, straightness and consistency of radial size. The press quench tooling and the process design have been mainly experience-based, using a trial and error approach for implementation of new processes, new gear materials and gear configurations.

294 Facing the Future - Emerging Technologies in Heat Treating (July 2018)

The following article highlights some of the recent heat treat products, technologies and industry news articles for gear manufacturing.

295 Loading Upgrades (March/April 2019)

The latest advances in gear manufacturing automation all seem to revolve around a common theme: automated loading.

296 What is the Latest in Heat Treating (March/April 2018)

The following article highlights some of the new heat treat products, technologies and industry news articles that have come across our desks.

297 Pardon the Disruption (January/February 2018)

Emerging technologies such as robotics/automation, new materials, additive manufacturing and IIoT can and will change the course of gear manufacturing for the foreseeable future.

298 Skiving is Thriving on a Global Scale (January/February 2018)

Call it new wine in old bottles, or old wine in new bottles, but gear skiving has certainly aged well over time. Gear skiving's evolution, perhaps gaining momentum most dramatically since around 2004, has ultimately led to rather dramatic technological advancement and cost saving in the manufacture of certain gears.

299 Solutions for Your Process Engineer Shortage (January/February 2018)

As you might imagine, I talk to many gear industry people through the course of my day-to-day activities. And there is one question that I hear over and over again. "Joe, we need an experienced gear process engineer. Do you know anyone who's available?"

300 Cyber Physical Gear Production System: A Vision of Industry 4.0 Gear Production (January/February 2018)

This report describes Klingelnberg's vision of Industry 4.0 gear production.

301 Analysis of the Influence of the Working Angles on the Tool Wear in Gear Hobbing (January/February 2018)

A calculation method is developed to estimate tool wear on hobs.

302 Globalization's Effect Upon Gear Steel Quality (January/February 2018)

Background on the development of a high-speed, automatic hardness tester for gear steels.

303 Industry News (January/February 2018)

Fraunhofer CMI focuses on new U.S. gear and transmission technologies group, plus other news from around the industry.

304 Liebherr - Barber Colman Hob Settings (September/October 2015)

I would like some instructions for setting the degrees and minutes on a Liebherr or Barber Colman hob. Our machines use a Vernier scale to match the lead angle of the cutter to the part to form straight teeth. There is a dispute on how to do this task, and I wanted insight from another professional.

305 Training the Next Generation (March/April 2018)

Last issue, when I went over the results from our annual State of the Gear Industry survey, I was being too nice. Sure, there's still a lot of optimism about the business climate. Gear manufacturers are mostly busy. For most, 2018 looks like it will be at least a little better than 2017. But there are dark clouds ahead, and they've been building for some time.

306 Product News (March/April 2018)

New machining fluids for automotive, jaw boring rings, virtual machine simulation and coordinate measuring software are highlighted in the March/April 2018 issue of Gear Technology.

307 Pushing Boundaries (March/April 2018)

Induction hardening is becoming an increasingly popular alternative to thermochemical diffusion processes such as carburizing, and as it does so, manufacturers are on a never-ending quest to expand the scope of what's possible with the technology.

308 A Look at Intelligent Workholding and Toolholding (March/April 2018)

New Solutions Aim at Reducing Changeover Times and Improving Reliability

309 In-Process, Complete Gear Inspection at Light Speeds (July 2018)

New GRSL technology adds value to high-volume transmission gear inspection by combining non-contact laser inspection with tried-and-true composite roll testing.

310 Effect of Non-Metallic Inclusions on Bending Fatigue Performance in High Strength 4140 Steel (March/April 2018)

Three samples of quenched and tempered 4140 steel, with varying levels of oxygen and sulfur, were submitted to a series of bending fatigue tests.

311 Annual Report (May 2018)

At most family reunions, everyone gets along, everyone puts on a good face, and everyone celebrates their togetherness. The AGMA annual convention held at the end of April was a lot like that.

312 More Solutions, Greater Challenges (May 2018)

As coating technology improves to handle harsher conditions, cutting tool manufacturers are faced with new challenges during the resharpening process.

313 Broaching in the 21st Century (May 2018)

Back around 2005-2010, the most exciting things that were happening in broaching had little to do with broaching. What was happening - and continues to evolve today - was the emergence of on-the-edge CNC, software and servo drive technology. Together, they practically transformed a metalworking process as old as water into a viable, alternative consideration for producing high-volume part runs.

314 Calculated Gear Life Values (May 2018)

I have a query (regarding) calculated gear life values. I would like to understand for what % of gear failures the calculated life is valid? Is it 1-in-100 (1% failure, 99% reliability) or 1-in-one-thousand (0.1% failure)?

315 Industry News (May 2018)

The complete industry news section from the May 2018 issue of Gear Technology.

316 Cutting Down on Setup Time (June 2018)

With increasingly smaller returns from improving the speed of the actual gear grinding process, improving your setup time has become a primary way to keep improving efficiency. Here's the latest on how you can do that today.

317 Predicting Life on Through Hardened Steel Rack and Pinion for Jacking Applications in the Offshore Industry (June 2018)

Designing and sizing a rack-and-pinion system, per AGMA and ISO gear calculation.

318 Human Machine Interface (HMI) in Gear Manufacturing (June 2018)

"Documentation is not a Substitute for an Intuitive Interface." The author explores the development of modern controls for a CNC gear grinding machine.

319 Standard Samples for Grinder Burn Etch Testing (June 2018)

A different method to produce a sample that has a very consistent amount of thermal damage.

320 Industry News (June 2018)

The complete industry news section from the June 2018 issue of Gear Technology.

321 Overlapping Pursuits (July 2018)

More than any other field, IIoT overlaps directly with metrology's mission to analyze and measure as much of the manufacturing process as possible, and it's no surprise that the latter is utilizing the former.

322 The Quick-Change Advantage (March/April 2019)

Workholding Systems Continue to Focus on Speed and Efficiency to Improve Machining Operations

323 Fluid Fundamentals (March/April 2019)

PSP Peugeot Improves Production Process with Blaser Swisslube

324 Praewema Antriebstechnik Develops Precise Machining Solutions for Planetary Gearing (January/February 2018)

The DVS gearing specialist Praewema Antriebstechnik continues to expand its technological expertise in order to keep pace with the growing significance of planetary geartrains for automatic and particularly electric vehicles, with the associated need for even higher-precision production of toothed gear components.

325 Product News (March/April 2020)

Gleason skiving machines equipped with on-board cutter sharpening; Helios celebrates anniversary of cutter sharpener line; and more product news.

326 Reverse Cutter Hand for Face Milling and Face Hobbing (November/December 2019)

Is a left-hand cutter required for a left-hand face mill part?

327 Industry News (November/December 2019)

The complete Industry News section from the November/December 2019 issue of Gear Technology.

328 Improving Cost Efficiency in Heat Treatment (January/February 2020)

The future gives the gear market plenty to think about in areas like automation, additive manufacturing and machine learning.

329 The Latest in Broaching (January/February 2020)

From standardization to automated, Industry 4.0 capable broachers, here's the latest in what's being developed in the field of broaching.

330 Training - A Top Priority for Investment (January/February 2020)

In this edition of Arvin's Angle, Joe explains why training isn't an expense. It's an investment.

331 Vickers vs. Knoop Hardness Testers for Measuring Case Depth in Carburized Parts (January/February 2020)

What are the pros and cons of using Vickers versus Knoop hardness testers for measuring case depth in carburized gears?

332 Bevel Gear Generators Get Better with Age (January/February 2020)

An economical modernization program gives Designatronics' tried-and-true Gleason No. 102 Coniflex generators a new lease on life for fast, reliable production of smaller precision straight bevel gears.

333 CNC Manufacturing of Circular Faced Cylindrical Gears (January/February 2020)

Spur cylindrical gears are usually cut using a hob and therefore present an essentially straight face to which crowning can be added to prevent edge contact. Rather than using a rack or hob, it is possible to cut cylindrical gears with a face mill cutter. In the following presentation, these gears are termed "spurved," i.e. — a contraction of "spur" and "curved."

334 Optimum Carburized and Hardened Case Depth (January/February 2020)

The optimum carburized and hardened case depth for each gear failure mode is different and must be defined at different locations on the gear tooth. Current gear rating standards do not fully explain the different failure modes and do not clearly define the different locations that must be considered.

335 Grinding Wheel Wear, Dressing, Tip Advance and Work Phase Angle Adjustment after Corrections (January/February 2020)

Are there rules to aid in grinding process optimization?

336 Industry News (January/February 2020)

Kapp Niles celebrates young inventors, Solar Atmospheres expands, Klingelnberg increases training programs, Liebherr celebrates 50 years in the USA, Timken Expands Southeast regional repair facility and more news for the gear industry.

337 Tinkering with Carbide (March/April 2020)

Everybody's working with carbide tools these days, but carbide materials are expensive. However, these cutting tool companies think they might have some solutions to extend tool life and reduce costs.

338 A Precise Prediction of the Tooth Root Stresses for Involute External Gears with Any Fillet Geometry under Consideration of the Exact Meshing Condition (September/October 2019)

This paper shows a method to calculate the occurring tooth root stress for involute, external gears with any form of fillets very precisely within a few seconds.

339 Calculated Scuffing Risk: Correlating AGMA 925-A03, AGMA 6011-J14 and Original MAAG Gear Predictions (March/April 2020)

This paper relates specifically to gears that are finish ground and considered high speed per ANSI/AGMA 6011; meshing elements with PLVs (pitch line velocities) in excess of 35 m/s or rotational speeds greater than 4,500 rpm.

340 Inside Look at the Hard Finishing Cell (May 2020)

Gleason Combines Threaded Wheel Grinding with GRSL Gear Inspection

341 Prototyping on Bevel Gear Cutting and Grinding Machines (May 2020)

Why Prototyping with End-mills on Bevel Gear Machines? Manufacturing of spiral bevel and hypoid gears can be conducted in several ways.

342 Heat Treating News (June 2020)

Furnace Suppliers and Heat Treaters Remain Busy During Tough Times

343 Additive Manufacturing - An Update (June 2020)

Writing about additive manufacturing (AM) and the 3-D printing of gears is somewhat akin to publishing an updated dictionary. A new edition dictionary is literally already out of date before it hits Amazon's or your local bookseller's shelves. New words are coined and definitions are updated constantly. So it is with AM: The technology is evolving so quickly that technical papers and other sources of AM information require constant revision.

344 Crossroads and Transitions - Part II (July 2009)

The auction has been held. The warehouse is bare. The computers and furniture are being packed, and Cadillac Machinery, the company started by my father in 1950, and of which I was president for more than 25 years, is close to being no more.

345 Reinvesting in New Equipment Pays Dividends (November/December 2007)

Recently, I was approached by a colleague who is a manufacturer outside the gear industry...

346 Back in the Good Old Days (September/October 1998)

Come with us now to those thrilling days of yesteryear...Ok, this is not the Cisco Kid, but we do have a little game for you. Guess the year the following advertisements and excerpt were printed - they all appeared in a dingle issue of Machinery Magazine.

347 GT Extras (January/February 2014)

Video from C&B Machinery; Introducing the Gear Technology Blog, featuring technical editor Charles D. Schultz; plus an online-exclusive article on big gear inspection.

348 Thermal Behavior of a High-Speed Gear Unit (January/February 2016)

In this paper a thermal network model is developed to simulate the thermal behavior of a high-speed, one-stage gear unit which is jet-lubricated.

349 Grinding It Out (January/February 2018)

C & B Machinery Meets Rigorous Demands with Installation of Manufacturing Cell.

350 Product News (September/October 2018)

See the latest gear industry products from Marposs, GWJ Technology, Norton|Saint Gobain, Mitutoyo, C&B Machinery, DMG Mori, Gear Motions and LK Metrology.

351 The Skiving Evolution (November/December 2019)

Machine Tool Providers Discuss the Latest Benefits, Technologies and Considerations

352 Design Parameters for Spline Connections (September/October 2019)

This article provides a guideline for the selection of a suitable standard in connection with the kind of spline to be designed and manufactured. Some basic formulae have been explained, together with a strategy on how to find standard tooling by calculating an appropriate profile shift factor for the spline to be designed.

353 Experimental Study on the Pitting Detection Capabilities for Spur Gears Using Acoustic Emission and Vibration Analysis Methods (March/April 2019)

An experimental investigation on spur gears to characterize pitting degradation process using monitoring features.

354 Measurement Management (July 2019)

The secret to meeting today's inspection demands is influenced by the technology and those in charge of operating it.

355 New Consideration of Non-Metallic Inclusions Calculating Local Tooth Root Load Carrying Capacity of High-Strength, High-Quality Steel Gears (March/April 2019)

The effects of non-metallic inclusions in steel matrix on tooth root strength based on theoretical approach of Murakami.

356 Industry News (March/April 2019)

The complete Industry News section from the March/April 2019 issue of Gear Technology.

357 Product News (May 2019)

The complete Product News section from the May 2019 issue of Gear Technology.

358 Cutting Tool Dynamics (May 2019)

Meeting Today’s Requirements for High-Quality Gears

359 Prediction of Process Forces in Gear Honing (May 2019)

Gear honing is a highly productive process for the production of small and medium sized gears and is used mainly in the serial production of the automotive industry. The low robustness of the process is a particular challenge in gear honing. The consequences range from an inadequate gear quality to an early breakage of the honing tool. In order to describe the processmachine interaction, the machining forces must be known.

360 Generative Gear Milling (May 2019)

This paper outlines the basic principles of involute gear generation by using a milling cutter; the machine and cutting tool requirements; similarities and differences with other gear generative methods; the cutting strategy; and setup adjustments options. It also discusses the applications that would benefit the most: for coarse-pitch gears the generative gear milling technologies offer improved efficiency, expanded machine pitch capacity, decreased cutter cost, and a possibility for reducing the number of machining operations.

361 The Do-It-Yourself Mentality (June 2019)

Finding capable, dependable machinists is one of the great challenges of modern manufacturing. Most gear manufacturers we talk to would hire more machine operators - if only they could find them. They lament the fact that their workforce is getting older and grayer, and they don't know what to do.

362 Identifying Equipment Failure (June 2019)

How machine tool maintenance has evolved in recent years in gear manufacturing.

363 Fine Grinding on Klingelnberg Bevel Gear Grinding Machines (June 2019)

One way to implement the growing performance requirements for transmissions is by optimizing the surface finish of the gearing. In addition to increasing the flank load capacity and the transmittable torque, this also allows for improvements in efficiency. On Oerlikon bevel gear grinding machines from Klingelnberg, fine grinding can be implemented efficiently in bevel gear production - even in an industrial serial process.

364 Method for High Accuracy Cutting Blade Inspection (June 2019)

Inspection of the cutting blades is an important step in the bevel gear manufacture. The proper blade geometry ensures that the desired gear tooth form can be achieved. The accuracy of the process can be compromised when the blade profile consists of several small sections such as protuberance, main profile, top relief and edge radius. Another common obstacle - are outliers which can be caused by dust particles, surface roughness and also floor vibrations during the data acquisition. This paper proposes the methods to improve the robustness of the inspection process in such cases.

365 Product News (July 2019)

The complete Product News section from the July 2019 issue of Gear Technology.

366 Heat-Treat Trends (July 2019)

The U.S. heat treat industry is in the middle of a labor shortage. Here's a look at what companies in the industry are doing about it.

367 Show Stoppers (September/October 2019)

Motion + Power Technology Expo VIP Exhibitors special advertising section.

368 Chamfering: Hard vs Soft Parts and Before vs After Heat Treating (July 2019)

The author conducts a simple experiment to verify his anecdotal knowledge about chamfering hard vs soft parts.

369 Fully Automated Roughness Measurement on Gears — Even on the Shop Floor (July 2019)

Klingelnberg presents the technical aspects of its roughness measurement system.

370 Industry News (July 2019)

The complete Industry News section from the July 2019 issue of Gear Technology.

371 A Bar/Restaurant for Gearheads (July 2019)

It's called GearHouse Brewing Co. It's in Chambersburg, a small town in south-central Pennsylvania. And it's fit for a gearhead. The bar/restaurant is decorated inside and out with more than 15 gears and gear blanks.

372 Taking the Wait Out of High Quality Gear Blanks (August 2019)

Forest City Gear makes the investment to bring gear blanking in-house, giving it complete control over quality and delivery: because failure’s not an option.

373 Super Skiving Cutter (August 2019)

Mitsubishi Heavy Industries, Ltd. (MHI) conducted a comparison test between the super skiving cutter and the pinion skiving cutter used in the conventional skiving process and the test results are reported here.

374 MPT Expo is all about Learning (August 2019)

In addition to hundreds of relevant suppliers, Motion+Power Technology Expo (Oct. 15-17 in Detroit) also offers many opportunities for learning.

375 Heat Treat 2019 (August 2019)

As the way things are manufactured continues to evolve, manufacturing trade shows are keeping pace with that evolution. A perfect example of that can be found at this year’s biennial Heat Treat 2019 (Oct. 15–Oct. 17, COBO Center, Detroit)

376 Overcoming Barriers (August 2019)

Depending on who you ask, the Industrial Internet of Things is growing more slowly than anyone predicted. Why is that, and what does that mean for the gear manufacturing industry?

377 A Tale of Two Gear Companies (August 2019)

Experiencing a Dickensian dilemma in its essence, a Los Angeles based manufacturing company was faced with the good fortune of ever increasing orders for steel gears from a good customer with a new recreational product in very high demand. Confronting the possibility of an untold number of lonely late nights tending to the whims of a 1950s era manual hobber was an unpalatable prospect no one desired.

378 Impact of Root Geometry Manufacturing Deviations from a Theoretical Hob Rack on Gear Bending Stress (August 2019)

This study emphasizes the importance of a closed-loop approach togear design and manufacturing to assure designed root fillet shapes are attained in production, and gears meet the design intent.

379 Product News (September/October 2019)

The complete Product News section from the September/October 2019 issue of Gear Technology.

380 Holding Fast, Bouncing Back (January/February 2018)

Business is finally starting to get back to usual in the big gear world, which offers us a chance to look back at the greatest lesson on how to survive an economic downturn. Includes the sidebar: "Brass Tacks with Klingelnberg."

381 There's a Story Here (January/February 2018)

As the founder, president and co-host of Manufacturing Talk Radio, as well as publisher of Metals & Manufacturing Outlook eZine, I am excited to report that the economic outlook for 2018 is just too good not to tout. Whatever "final GDP number" the government divines for 2017, the year will finish above 3% for the first time in a decade.

382 Prediction of Surface Zone Changes in Generating Gear Grinding (March/April 2015)

One process for hard finishing gears is generating gear grinding. Due to its high process efficiency, generating gear grinding has replaced other grinding processes such as profile grinding in batch production of small- and middle-sized gears. Yet despite the wide industrial application of generating gear grinding, the process design is based on experience along with time- and cost-intensive trials. The science-based analysis of generating gear grinding demands a high amount of time and effort, and only a few published scientific analyses exist. In this report a thermo-mechanical process model that describes influences on the surface zone in generating gear grinding is introduced.

383 Industry News (July 2016)

Latest News from around the industry

384 The Gear Industry Needs You (May 2016)

your life and in your professional career is an inflection point for you to take stock of where you came from and where you are going.

385 Industry News (May 2016)

Lastest news from around the industry.

386 Make Volunteering the Norm (May 2016)

This is a very exciting year for AGMA as the organization celebrates its 100-year anniversary. In addition to the anniversary, AGMA President Joe Franklin, jr., who has done an outstanding job at the helm of AGMA for the last 25 years, will retire, and we welcome in our new AGMA President, Matt Croson, who will lead us into the next 100 years. The centennial kicked off in October with a dinner at the AGMA Gear Expo in Detroit and will continue throughout 2016 with a number of exciting events scheduled to celebrate this milestone anniversary.

387 The Comprehensive Gear Grind (June 2016)

Looking for some simple yet useful advice heading into IMTS 2016? Never second guess your machine tool investment. Flexibility is a mandatory requirement in gear manufacturing today. Accuracy, reliability and efficiency must improve with each new machine tool purchase. Innovation is always the end game. So it comes as no surprise that IMTS 2016 attendees will have plenty of gear grinding technologies to consider this fall.

388 Hail to the Quick-Change King (June 2016)

It's the year of the quick-change tool. From chucks to mandrels, workholding manufacturers across the industry are seeing a continuing trend from their customers: give us more quickchange.

389 Innovations for High Productivity Generating Grinding (June 2016)

In comparison to the visionary Industry 4.0 - or the Fourth Industrial Revolution - the machine tool industry can appear rather down-to-earth.

390 Bevel Gear Cutting Methods (June 2016)

THE FINAL CHAPTER This is the last in the series of chapters excerpted from Dr. Hermann J. Stadtfeld's Gleason Bevel Gear Technology - a book written for specialists in planning, engineering, gear design and manufacturing. The work also addresses the technical information needs of researchers, scientists and students who deal with the theory and practice of bevel gears and other angular gear systems. While all of the above groups are of course of invaluable importance to the gear industry, it is surely the students who hold the key to its future. And with that knowledge it is reassuring to hear from Dr. Stadtfeld of the enthusiastic response he has received from younger readers of these chapter installments.

391 Checking Up on Your Heat Treater (July 2016)

What quality and performance characteristics should you look for?

392 IMTS: Welcome to the Main Event (July 2016)

It's hard to think of a show more essential to attend than IMTS. It's the cornerstone event for the industry, the center of the universe for a week, the one show to rule them all.

393 Improved Broaching Steel Technology (July 2016)

Broaching is a machining technique commonly used to cut gear teeth or cam profiles for the high volume manufacture of power transmission parts used in vehicles (Refs. 1–2). This article shows how the right gear blank material can make all the difference if you want to get more parts out of each tool.

394 Influence of Hobbing Tool Generating Scallops on Root Fillet Stress Concentrations (July 2016)

While designing gear and spline teeth, the root fillet area and the corresponding maximum tensile stress are primary design considerations for the gear designer. Root fillet tensile stress may be calculated using macro-geometry values such as module, minor diameter, effective fillet radius, face width, etc.

395 Chamfering and Deburring - the Underrated Process (August 2016)

Chamfering and deburring of cylindrical gears does not get much love from manufacturers. The process is seen as a necessary evil since it is adding cost without adding value. However, there are good reasons for not underrating this important auxiliary process. Chamfering and deburring takes care of several issues which may come up during the manufacture of quality gears.

396 Industry News (March/April 2016)

News from around the Gear Industry

397 Updating Modern Production Processes (August 2016)

Gear Technology interviews Scott Yoders of Liebherr about the latest gear machining technologies of relevance to automotive manufacturers.

398 IMTS Booth Listings (August 2016)

The suppliers of products or services that may be of interest to gear manufacturers who visit IMTS 2016.

399 IMTS 2016 Booth Previews (August 2016)

Comprehensive descriptions of what you will find in the booths of many leading gear industry suppliers at IMTS 2016.

400 Show Stoppers (August 2016)

Our special advertising section featuring some of the premier gear industry suppliers at IMTS 2016.

401 What Was He Thinking (August 2016)

Having read about an automobile race in France, Kohlsaat decided he'd host America's first auto race in Chicago. The year was 1895 and automobiles were still a great curiosity. Kohlsaat, owner/publisher of the Chicago Times Herald, planned to exploit the growing interest in motoring by sponsoring a 54-mile race from downtown Chicago to nearby suburb Evanston, Illinois, and back. The match was open to all comers, foreign or domestic, whether powered by gas, electricity, or steam. The top prize: $2,000 (that's 50,000 2016 dollars).

402 Product News (September/October 2016)

News on the latest products in the industry.

403 Innovating Against the Tide (September/October 2016)

During a year with a strong dollar, tanked oil prices and a number of soft markets that just aren't buying, one might expect spline manufacturers to be experiencing the same tumult everyone else is. But when I got a chance to speak with some of the suppliers to spline manufacturers at IMTS about how business is going, many of the manufacturing industry's recent woes never came up, and instead were replaced by a shrug and an "eh, business is doing pretty well."

404 Same Hob for Two Gears (September/October 2016)

I make all the double helical gears that go into a gearbox - four different gears in this unit. If the gear module for the bull gear and the intermediate gear are the same (these are the two individual gears that mate), and the gear module for the high-speed pinion and high-speed gears are the same (these are the other two individual gears that mate in the gear box as well), is it then possible to just use two hobs in this setup to make all four gears, since they mate together with each other? We are currently using a different gear hob for each gear.

405 Increased Tooth Bending Strength and Pitting Load Capacity of Fine-Module Gears (September/October 2016)

The common calculation methods according to DIN 3990 and ISO 6336 are based on a comparison of occurring stress and allowable stress. The influence of gear size on the load-carrying capacity is considered with the size factors YX (tooth root bending) and ZX (pitting), but there are further influences, which should be considered. In the following, major influences of gear size on the load factors as well as on the permissible tooth root bending and contact stress will be discussed.

406 A Proposed Pre-Finish Cylindrical Gear Quality Standard (September/October 2016)

This proposed standard would not make any recommendations regarding the required quality for any application. The intent is to establish standard pre-finish quality classes for typical finishing operations, which only include the inspection elements that are important to properly evaluate pre-finish gear quality as it applies to the finishing operation. It would be the responsibility of the manufacturing/process engineer, quality engineer, or other responsible individual to establish the required pre-finish quality class for their application.

407 Industry News (September/October 2016)

News From Around the Gear Industry

408 DIGITIZE or DIE (November/December 2016)

In a capitalist society, the way things usually work is that government and academia focus on research and development, while industry focuses on commercialization. The result is an increasingly wide disconnect in the applied research sector, which deals primarily with technology development and demonstration.

409 Adding Up Gear Spheres (March/April 2016)

Paul Nylander is something between an entrepreneur and a Renaissance man. He has degrees in engineering and physics, but he's also a creative artist who's put together sketches and 3D renderings alike. His website, bugman123. com, features everything from an in-depth explanation of a Tesla coil to 3D renderings of physics equations to an extensive library of fractal-based artwork. At first glance, one might find Nylander's many pursuits to be somewhat scattershot, but at their core, his works are tied together by his love for all things mathematical.

410 Practical Gear Characteristics: Process Characteristics of the Most Popular Cutting Methods (March/April 2016)

The cutting process consists of either a roll only (only generating motion), a plunge only or a combination of plunging and rolling. The material removal and flank forming due to a pure generating motion is demonstrated in the simplified sketch in Figure 1 in four steps. In the start roll position (step 1), the cutter profile has not yet contacted the work. A rotation of the work around its axis (indicated by the rotation arrow) is coupled with a rotation of the cutter around the axis of the generating gear (indicated by the vertical arrow) and initiates a generating motion between the not-yet-existing tooth slot of the work and the cutter head (which symbolizes one tooth of the generating gear).

411 The Role of Natural Frequencies in Grinding Systems Vibration (November/December 2016)

Excessive machine tool vibration during a precision grinding operation can result in poor workpiece quality in the form of chatter, rough finishes, burn, etc. One possible reason for excessive vibration is directly associated with the relationship between natural frequencies of a machine tool system and the operating speed of the grinding wheel spindle.

412 Sourcing Gears and Gear-Related Products (August 2015)

Reshoring offers an opportunity for increased domestic gear production. Reshoring is growing at a steady pace in most industries, and is particularly strong in the gear intensive industries such as automotive, aerospace and construction equipment (Table 1). This article provides background on the overall trend and tools for the gear buyer and the gear producer to make the offshore vs. domestic decision.

413 A Practical Approach for Modeling a Bevel Gear (March/April 2015)

The geometry of the bevel gear is quite complicated to describe mathematically, and much of the overall surface topology of the tooth flank is dependent on the machine settings and cutting method employed. AGMA 929-A06 — Calculation of Bevel Gear Top Land and Guidance on Cutter Edge Radius — lays out a practical approach for predicting the approximate top-land thicknesses at certain points of interest — regardless of the exact machine settings that will generate the tooth form. The points of interest that AGMA 929-A06 address consist of toe, mean, heel, and point of involute lengthwise curvature. The following method expands upon the concepts described in AGMA 929-A06 to allow the user to calculate not only the top-land thickness, but the more general case as well, i.e. — normal tooth thickness anywhere along the face and profile of the bevel gear tooth. This method does not rely on any additional machine settings; only basic geometry of the cutter, blank, and teeth are required to calculate fairly accurate tooth thicknesses. The tooth thicknesses are then transformed into a point cloud describing both the convex and concave flanks in a global, Cartesian coordinate system. These points can be utilized in any modern computer-aided design software package to assist in the generation of a 3D solid model; all pertinent tooth macrogeometry can be closely simulated using this technique. A case study will be presented evaluating the accuracy of the point cloud data compared to a physical part.

414 Industry News (March/April 2015)

The complete Industry News section from the March/April 2015 issue of Gear Technology.

415 Times Arent A-Changin for Broaching, and Thats Just Fine (May 2015)

In 1964, a young and tidy Bob Dylan sang away in that infamous voice of his, all nasally and grating yet wonderfully distinct, opining to the fervent masses: “The times, they are a-changin.”

416 An Approach to Pairing Bevel Gears from Conventional Cutting Machine with Gears Produced on 5-Axis Milling Machine (June 2015)

Developed here is a new method to automatically find the optimal topological modification from the predetermined measurement grid points for bevel gears. Employing this method enables the duplication of any flank form of a bevel gear given by the measurement points and the creation of a 3-D model for CAM machining in a very short time. This method not only allows the user to model existing flank forms into 3-D models, but also can be applied for various other purposes, such as compensating for hardening distortions and manufacturing deviations which are very important issues but not yet solved in the practical milling process.

417 Bevel Grinding Rolling Right Along (June 2015)

When Dr. Hermann J. Stadtfeld speaks, people tend to listen. Considered one of the world’s foremost experts on bevel gears, Stadtfeld, the vice president of bevel gear technology at Gleason, recently revealed several cutting-edge advancements that the company has been working on.

418 Gear Grinding is Getting Easier, Better, Faster, Stronger (June 2015)

Liebherr is well-known as one of the world’s largest privately owned companies — a titan in heavy industry specializing in cranes, trucks and mammoth earth moving and mining equipment.

419 Industry News (June 2015)

News from Around the Gear Industry

420 Optimal Modifications on Helical Gears for Good Load Distribution and Minimal Wear (June 2015)

Helical gear teeth are affected by cratering wear — particularly in the regions of low oil film thicknesses, high flank pressures and high sliding speeds. The greatest wear occurs on the pinion — in the area of negative specific sliding. Here the tooth tip radius of the driven gear makes contact with the flank of the driving gear with maximum sliding speed and pressure.

421 Manufacturing Jobs Are There - Workers to Fill Them ARE NOT (July 2015)

An all too common — and disturbing — question these days: Are you having trouble finding skilled workers? Taking that a step further begs the next question — Are you having trouble finding customers with

422 Dont Get Burned (July 2015)

Questions to Ask Your Heat Treater Provided by Justin Lefevre (Joyworks LLC, Ann Arbor, MI), Kathy Hayrynen (Applied Process, Inc., Livonia, MI) and Vasko Popovski (Applied Process, Inc.)

423 Determining Bull Gear Wear (July 2015)

We are currently experiencing wear on the bull gear on our converter at the steel plant. We want to be able to draw the original gear profile to compare this with the worn tooth before we decide on the next steps. I have attempted this, but there is a correction factor given and I am unsure how to apply this. Could someone give advice on this? Please find attached the PDF’s for the bull gear and the pinion gear. They are old drawings! The wear is on the wheel.

424 Product News (September/October 2015)

News about New Products

425 Practical Approach to Determining Effective Case Depth of Gas Carburizing (March/April 2016)

Effective case depth is an important factor and goal in gas carburizing, involving complicated procedures in the furnace and requiring precise control of many thermal parameters. Based upon diffusion theory and years of carburizing experience, this paper calculates the effective case depth governed by carburizing temperature, time, carbon content of steel, and carbon potential of atmosphere. In light of this analysis, carburizing factors at various temperatures and carbon potentials for steels with different carbon content were calculated to determine the necessary carburizing cycle time. This methodology provides simple (without computer simulation) and practical guidance of optimized gas carburizing and has been applied to plant production. It shows that measured, effective case depth of gear parts covering most of the industrial application range (0.020 inch to over 0.250 inch) was in good agreement with the calculation.

426 Gear Macrogeometry (September/October 2015)

I have outsourced gear macrogeometry due to lack of resources. Now I received the output from them and one of the gears is with —0.8× module correction factor for m = 1.8 mm gear. Since bending root stress and specific slide is at par with specification, but negative correction factor —0.8× module — is quite high — how will it influence NVH behavior/transmission error? SAP and TIF are very close to 0.05 mm; how will that influence the manufacturing/cost?

427 Gear Tooth Surface Roughness of Helical Gears Manufactured by a Form Milling Cutter (September/October 2015)

Manufacturing involute gears using form grinding or form milling wheels are beneficial to hobs in some special cases, such as small scale production and, the obvious, manufacture of internal gears. To manufacture involute gears correctly the form wheel must be purpose-designed, and in this paper the geometry of the form wheel is determined through inverse calculation. A mathematical model is presented where it is possible to determine the machined gear tooth surface in three dimensions, manufactured by this tool, taking the finite number of cutting edges into account. The model is validated by comparing calculated results with the observed results of a gear manufactured by an indexable insert milling cutter.

428 Coated Gears Provide Slick Solution for Human-Powered Boat (January/February 1997)

Design Problem: Develop a gear drive for a pedal-powered water craft that will be easy to manufacture, use and maintain; that will be lightweight enough for the boat to be portable; and that will eliminate the environmental risk of lubricants leaking into the water.

429 Product News (November/December 2015)

News about recent products

430 Process Model for Honing Larger Gears (November/December 2015)

Hard finishing technology, e.g. — honing — is used to manufacture high-performance gears. Gear honing is primarily used to hard finish small- and medium-sized automotive gears. And yet trials have shown that gears with a module larger than mn = 4 mm can also be honed efficiently, but problems often occur due to unstable process design. In this paper a model to improve the process design is described.

431 Product News (January/February 2016)

Latest news about the Latest Products

432 Looming Large (January/February 2016)

Let's talk about large gears. Not the size or scope or inspection process, but the forecast and market potential in areas that utilize these massive components. We'll examine key industry segments like energy and mining and tap IHS Economics for a forecast for 2016 and 2017 (spoiler alert: it's not great). Additionally, we'll discuss some of the critical factors influencing global big gear manufacturers Ferry-Capitain and Hofmann Engineering.

433 Influences on Failure Modes and Load-Carrying Capacity of Grease-Lubricated Gears (January/February 2016)

In order to properly select a grease for a particular application, a sound knowledge of the influence of different grease components and operating conditions on the lubrication supply mechanism and on different failure modes is of great benefit.

434 Critique of the ISO 15144-1 Method to Predict the Risk of Micropitting (March/April 2016)

There exists an ongoing, urgent need for a rating method to assess micropitting risk, as AGMA considers it a "a very significant failure mode for rolling element bearings and gear teeth - especially in gearbox applications such as wind turbines."

435 Defying the Oil Ripple (March/April 2016)

The oil industry is (pardon the pun) tanking. That may conjure up horrific images of other industries following suit in a domino effect of collective collapse into the overabundant oil slick the industry is currently drowning in, but not everyone is getting knocked down alongside the oil sector.

436 Taking on Tight Margins in Wind Energy (March/April 2016)

Onshore and offshore wind turbines boast some of the most critical assets in order to run effectively.

437 Hard-Finishing Spiral Bevel Gears (March/April 2016)

Could you explain to me the difference between spiral bevel gear process face hobbing-lapping, face milling-grinding and Klingelnberg HPG? Which one is better for noise, load capacity and quality?

438 Locating Multiple Bore Diameters Via Hobbing (November/December 2016)

Attached photos (Figs. 1-2) show a bushing to locate one single bore. This will be used to locate one single bore diameter of a gear wheel. What is (the latest) technology for common clamping a bushing to locate multiple bore diameters in hobbing?

439 Influence of Topography Deviations on the Psychoacoustic Evaluation of Ground Bevel Gears (November/December 2016)

In the design process of transmissions, one major criterion is the resulting noise emission of the powertrain due to gear excitation. Within the past years, much investigation has shown that the noise emission can be attributed to quasi-static transmission error. Therefore, the transmission error can be used for a tooth contact analysis in the design process, as well as a characteristic value for quality assurance by experimental inspections.

440 We'd Grow Faster If We Could (January/February 2018)

It's probably no surprise to anyone that the majority of the gear industry had a pretty good year in 2017, and that most gear manufacturers are expecting a pretty good 2018 as well. After all, most major economic indicators - including the ones that focus on the manufacturing sector - have been positive for some time.

441 The Multifunctional Option (August 2017)

Toyoda's new GS300H5 Gear Skiving Center is the first in the world to equip a skiving function to a general purpose horizontal machining center (HMC), through which mass production of gear parts is achieved. CNC controls and a high speed rotary table were developed specifically to achieve high-speed, multifunctional machining, as a compact and lightweight product, simple in programming functions.

442 Contact Fatigue Characterization of Through-Hardened Steel for Low-Speed Applications like Hoisting (July 2017)

In several applications like hoisting equipment and cranes, open gears are used to transmit power at rather low speeds (tangential velocity < 1m/s) with lubrication by grease. In consequence those applications have particularities in terms of lubricating conditions and friction involved, pairing of material between pinion and gear wheel, lubricant supply, loading cycles and behavior of materials with significant contact pressure due to lower number of cycles.

443 MicroPulse and MicroShift for Ground Bevel Gearsets (July 2017)

Grinding of bevel and hypoid gears creates on the surface a roughness structure with lines that are parallel to the root. Imperfections of those lines often repeat on preceding teeth, leading to a magnification of the amplitudes above the tooth mesh frequency and their higher harmonics. This phenomenon is known in grinding and has led in many cylindrical gear applications to an additional finishing operation (honing). Until now, in bevel and hypoid gear grinding, a short time lapping of pinion and gear after the grinding operation, is the only possibility to change the surface structure from the strongly root line oriented roughness lines to a diffuse structure.

444 Surface Characteristics of Hobbed Gears (July 2017)

Gear hobbing is one of the most productive manufacturing processes for cylindrical gears. The quality of the gears is a result of the tool quality, the precision of the workpiece, tool clamping and kinematics of the machine. The dry gear hobbing process allows machining of gears with a quality according to the DIN standard up to IT 5. To evaluate which gear quality is possible to machine with a given clamping and hob, it is useful to simulate the process in advance.

445 Industry News (July 2017)

AGMA adds two new committees, Star Cutter Celebrates 90 years, plus other news from around the industry.

446 Much Ado About Nothing (July 2017)

For over 50 years, the Do Nothing Machine has entertained the public eye with its complex machinery, a mountain of over 700 gears put together for the express purpose of doing nothing.

447 Columbus Calling (August 2017)

Summer never lasts as long as you want it to. By the time you read this, you'll be well into the hazy, lazy days, and the season will be gone before you know it. That means you're running out of time to make plans to attend our industry's most important event. Of course, I'm talking about Gear Expo (October 24 - 26) and the AGMA Fall Technical Meeting (October 22 - 24), both of which will take place in Columbus, OH.

448 Gear Expo 2017 (August 2017)

AGMA Sets Up Shop in Living Laboratory of the Midwest. Columbus, Ohio recently surpassed Indianapolis as the second largest city in the Midwest behind Chicago, according to the United States Census Bureau. This could change come the 2020 census, but there's no denying Buckeye Nation is going places.

449 2017 Gear Expo: Gears, Machinery and a Whole Lot More (August 2017)

There is so much more to Gear Expo than gears or the machinery that makes them. That's because it takes much, much more to make a finished gear than even the most sophisticated machine. And it is exhibitors who are part of the "much, much, more" that are addressed in this article.

450 Speed Matters - In Racing and in Hobbing (August 2017)

RCD Engineering's switch from manual to CNC hobbing operations breaks gear manufacturing lead time records with Bourn & Koch 100H in their gear production pit crew.

451 Skiving - A Manufacturing Renaissance (August 2017)

Skiving will be front and center when the gear industry comes together in Columbus this October. Attendees will find dedicated skiving equipment, multifunctional machines with skiving options and a slew of new cutting tools, machine designs and modifications to make the process more efficient and robust.

452 Hard Scudding - The Future Has Arrived (August 2017)

As the science of Scudding has rapidly evolved, the interest in the more advanced process Hard Scudding is increasing.

453 Efficient Hard Finishing of Asymmetric Tooth Profiles and Topological Modifications by Generating Grinding (August 2017)

In order to improve load-carrying capacity and noise behavior, gears usually have profile and lead modifications. Furthermore, in gears where a specified tooth-flank load application direction (for drive and coast flanks) is a design enhancement, or even compulsory, the asymmetric tooth profile is a further solution. Nowadays, many gears need to be hard finished. Continuous generating grinding offers a very high process efficiency, but is this process able to grind all modifications, especially asymmetric gears? Yes, it is!

454 Surface Structure Shift for Ground Bevel Gears (June 2017)

Ground bevel and hypoid gears have a designed motion error that defines parts of their NVH behavior. The surface structure is defined by the hard finishing process.

455 New Gear Technology at EMO Hannover 2017 (August 2017)

EMO is arguably the most important trade show when it comes to the introduction of machine tool technology, and this year's show - taking place from September 18-23 in Hannover, Germany - promises not to disappoint. We've talked to a number of gear manufacturing technology providers to give you a sneak peak of what you can expect to see if you attend this year.

456 Got Gear Questions - Get Gear Answers (September/October 2017)

Gear Expo 2017 is your best opportunity to expand your knowledge, get answers to your technical questions and solve your toughest manufacturing challenges. The reason is quite simple. Gear Expo provides you with the greatest collection of gear expertise, know-how and experience you can find.

457 The Valued Troublesome Employee (September/October 2017)

I'm sure it comes as no surprise that finding skilled people to work in your manufacturing facility is no simple task. But after finding them, and investing in the development of their abilities, what happens when one of them - an employee your company really needs - becomes a troublesome employee? This is among the trickiest situations a manager can face.

458 Gear Expo 2017 and ASM Heat Treat 2017 Booth Previews (September/October 2017)

The latest technology on display in Columbus, OH. October 24-26.

459 Tooth Contact Analysis - Off Line of Action Contact and Polymer Gears (September/October 2017)

The aim of the study was to apply such a specialized tooth contact analysis method, well-used within the steel gear community, to a polymer gear application to assess what modifications need be made to these models for them to be applicable to polymer gears.

460 Industry News (September/October 2017)

Bob Errichello retires from teaching, Siemens expands technical center, HBM Holdings acquires Schafer Industries, plus new hires and other industry news.

461 Strategies for Building Your Business (November/December 2017)

In this issue's column, Joe lays out the basic truth for most manufacturing companies: If you're not moving forward, you're falling behind.

462 Friction Coefficient of Differently Treated Steel Surfaces (November/December 2017)

A reader asks about ion-nitride finished shafts and the proper friction coefficient to be used for calculations.

463 Material Assets (November/December 2017)

You get one shot to make a first impression. One opportunity to show your customers, vendors and suppliers that you provide a steady, reliable product that will generate repeat business. How do you make this happen? What tools and strategies are available to get gear materials (forgings, gear blanks, etc.) shipped faster and more efficiently in today's tech-heavy, fast-paced, manufacturing environment?

464 Rating of Helical Asymmetric Tooth Gears (November/December 2017)

Although gear geometry and the design of asymmetric tooth gears are well known and published, they are not covered by modern national or international gear design and rating standards. This limits their broad implementation for various gear applications, despite substantial performance advantages in comparison to symmetric tooth gears for mostly unidirectional drives. In some industries — like aerospace, that are accustomed to using gears with non-standard tooth shapes — the rating of these gears is established by comprehensive testing. However, such testing programs are not affordable for many other gear drive applications that could also benefit from asymmetric tooth gears.

465 Three-Face Blade Technology (November/December 2017)

The author compares the standard two-face blade technology with the three-face blade technology for manufacturing bevel gears.

466 Influence of the Defect Size on the Tooth Root Load Carrying Capacity (November/December 2017)

The objective of this work is to introduce a method for the calculation of the tooth root load carrying capacity for gears, under consideration of the influence of the defect size on the endurance fatigue strength of the tooth root. The theoretical basis of this method is presented in this paper as well as the validation in running tests of helical and beveloid gears with different material batches, regarding the size distribution of inclusions. The torque level for a 50 percent failure probability of the gears is evaluated on the test rig and then compared to the results of the simulation. The simulative method allows for a performance of the staircase method that is usually performed physically in the back-to-back tests for endurance strength, as the statistical influence of the material properties is considered in the calculation model. The comparison between simulation and tests shows a high level of accordance.

467 Ask Not What Your Heat Treater Can Do for You... (July 2017)

When sending gears to be heat treated, manufacturers can end up unwittingly making mistakes that slow down turnaround time. We talked to some heat treaters to get their best advice on how you can help them help you.

468 Twist Control Grinding (June 2017)

This paper introduces the latest process developments for the hard-finishing of gears, specifically in regard to controlling the so-called flank twist.

469 Optimal Flank Forms for Large Bevel Gears (November/December 2016)

At first sight the appearance of 5-axis milling for bevel gears opens new possibilities in flank form design. Since in comparison to existing machining methods applying cutter heads no kinematic restrictions exist for 5-axis milling technology, any flank form can be machined. Nevertheless the basic requirements for bevel gears did not change. Specifications and functional requirements like load carrying capacity and running behavior are still increasing demands for design and manufacturing. This paper describes the demands for gear design and gives an overview about different design principles in the context of the surrounding periphery of the gear set.

470 Universal Hobs (March/April 2017)

Another expert takes a crack at a previously answered question about double-helical gears and universal hobs.

471 Industry News (November/December 2016)

News from around the Industry

472 Oil-Out Endurance Under the Lens (January/February 2017)

Oil-out conditions, or conditions in which an aircraft is operating without any oil in its gearbox or transmission, are devastating for an aircraft's hardware. Even the sturdiest gears usually can't last 30 minutes under such conditions before they catastrophically fail, and the whole system usually follows shortly after. That doesn't leave pilots with a whole lot of time to find a suitable location to land in the case of an oil-out emergency.

473 Best Tooling for Hard Milling a Gear Tooth on 5-Axis Machining Center (January/February 2017)

What is the best tooling to use when hard milling a gear tooth on a 5-axis machining center? And what makes it the best? We have just bought a DMG Mori mono-block and are not getting the finishes at the cycle times we require.

474 Development of High-Hardness-Cast Gears for High-Power Mining Applications (January/February 2017)

Multiple possibilities are available to increase the transmissible power of girth gears. These solutions include: using a larger module, increasing of the gear diameter through the number of teeth, enlarging the face width, and increasing the hardness of the base material. The first three parameters are mostly limited by cutting machine capability. Module, outside diameter, and face width (for a cast gear) can theoretically be increased to infinity, but not the cutting machine dimensions. There are also practical limits with respect to the installation of very large diameter/large face width gears.

475 Industry News (January/February 2017)

News from around the Gear Industry

476 Swiss Watchmaking - with 3-D Printing (January/February 2017)

For centuries, Switzerland has been considered home to the greatest watchmakers in the world. Works of fine beauty and optimal precision have been the norm there seemingly forever.

477 Transferring Tribal Knowledge (March/April 2017)

How do we educate the next generation of gear industry employees, and how do we train the ones we already have?

478 Message Received (March/April 2017)

Big Data Expands Process Capabilities for Multi-Axis Machining.

479 5-Axis Gear Manufacturing Gets Practical (March/April 2017)

Exciting new machine, cutting tool and software technologies are compelling many manufacturers to take a fresh look at producing their larger gears on machining centers. They're faster than ever, more flexible, easy to operate, highly affordable - and for any type of gear.

480 Heat Treating 4.0 (March/April 2017)

Suppliers are working hard to make sure their heat treating equipment is controllable, repeatable and efficient, and manufacturers continue to incorporate technology that gives heat treaters and their customers more information about what's going on inside the magic box.

481 It Doesn't Matter How Efficient Your Plant Is (March/April 2017)

To ensure profitability and avoid losses, accurately quoting jobs is the first line of defense.

482 Performance of Gears Manufactured by 5-Axis Milling (March/April 2017)

Free form milling of gears becomes more and more important as a flexible machining process for gears. Reasons for that are high degrees of freedom as the usage of universal tool geometry and machine tools is possible. This allows flexible machining of various gear types and sizes with one manufacturing system. This paper deals with manufacturing, quality and performance of gears made by free form milling. The focus is set on specific process properties of the parts. The potential of free form milling is investigated in cutting tests of a common standard gear. The component properties are analyzed and flank load-carrying capacity of the gears is derived by running trials on back-to-back test benches. Hereby the characteristics of gears made by free form milling and capability in comparison with conventionally manufactured gears will be shown.

483 Ground and Hobbed Globoidal Worm Sets (June 2017)

A reader wants to know: Are profile ground and hobbed globoidal worm sets better than multi-axis CNC generated globoidal worm gear sets for reduction of noise and vibration?

484 Industry News (March/April 2017)

Educational initiatives, company news, acquisitions and people in the industry are all featured this issue.

485 Product News (May 2017)

The latest from Liebherr, Gleason, Klingelnberg and more.

486 Upgrading Your Toolbox (May 2017)

Manufacturers focus on tool design, materials, coating, machine tool options and cutting parameters.

487 Gear Design Deconstructed (May 2017)

How difficult is it to design a gear? It depends upon whom you ask.

488 Can Lean Manufacturing Kill Your Job Shop (May 2017)

The presidents of two manufacturing companies were having a drink in the lobby before the start of their trade association's annual meeting...

489 Gear Teeth as Bearing Surfaces (May 2017)

A reader wonders about gears where the tops of the teeth are the bearing surface, as used in spur gear differentials. Do they require any special construction or processing?

490 Inclusion-Based Bending Strength Calculation of Gears (May 2017)

Reduced component weight and ever-increasing power density require a gear design on the border area of material capacity. In order to exploit the potential offered by modern construction materials, calculation methods for component strength must rely on a deeper understanding of fracture and material mechanics in contrast to empirical-analytical approaches.

491 Industry News (May 2017)

Faydor Litvin, 1914-2017; Michael Goldstein receives AGMA Distinguished Service Award.

492 The AGS Gear Industry Training Series (May 2017)

An Introduct to Gear Process Engineering.

493 Get Smarter at Gear Expo (June 2017)

There are many benefits to attending Gear Expo, but if you're not taking advantage of the educational opportunities, you're missing out.

494 Gear Grinding Today (June 2017)

New divisions, open houses and the continued rise of the Industrial Internet of Things - There's been a lot going on in gear grinding in the past year.

495 Anatomy of a Rebuild (June 2017)

Nuttall Gear taps Machine Tool Builders for shop floor upgrades.

496 The Way of the Web (March/April 1997)

Okay. You've been convinced. You've gritted your teeth and decided to spend the money to launch a company Web site. Everybody from your teenage propeller-head to the girl in the mail room and the salesman in the flashy suit who gave you "such a deal" on Web site services has promised that your site will be the best thing that's happened to your business since the advent of CNC machines.

497 Avoiding Interference In Shaper-Cut Gears (January/February 1996)

In the process of developing gear trains, it occasionally occurs that the tip of one gear will drag in the fillet of the mating gear. The first reaction may be to assume that the outside diameter of the gear is too large. This article is intended to show that although the gear dimensions follow AGMA guidelines, if the gear is cut with a shaper, the cutting process may not provide sufficient relief in the fillet area and be the cause of the interference.

498 Composite Electroless Nickel Coatings for the Gear Industry (January/February 1997)

Electroless Nickel (EN) plating, a process dating back to the 1940s, is one of the predominant metal finishing methods today. It is especially suitable for the gear industry, whose end uses span innumerable other industries, providing an endless assortment of requirements, environments, materials and specifications. EN plating has a broad array of functional features, which include:

499 Guidelines for Modern Bevel Gear Grinding (August 2008)

This paper acknowledges the wide variety of manufacturing processes--especially in grinding--utlized in the production of bevel gears...

500 What to Know About Bevel Gear Grinding (September/October 2005)

Guidelines are insurance against mistakes in the often detailed work of gear manufacturing. Gear engineers, after all, can't know all the steps for all the processes used in their factories.

501 A Split Happened on the Way to Reliable, Higher-Volume Gear Grinding (September/October 2005)

Bevel gear manufacturers live in one of two camps: the face hobbing/lapping camp, and the face milling/grinding camp.

502 Measuring Pitch Diameter (September/October 2005)

Wait a minute, we don't measure pitch diameter. We're sometimes asked to measure it by customers, though, especially ones with older drawings.

503 A Lean Strategy for Job Shops (November/December 2005)

POLCA: An alternative to Kanban for high-variety or custom-engineered products.

504 Methodology for Translating Single-Tooth Bending Fatigue Data to be Comparable to Running Gear Data (March/April 2008)

A method to extrapolate running gear bending strength data from STF results for comparing bending performance of different materials and processes.

505 Operational Condition and Superfinishing Effect on High-Speed Helical Gearing System Performance (March/April 2008)

An experimental effort has been conducted on an aerospace-quality helical gear train to investigate the thermal behavior of the gear system. Test results from the parametric studies and the superfinishing process are presented.

506 Pitting Load Capacity of Helical Gears (May 2008)

Influences of Load Distribution and Tooth Flank Modifications as Considered in a New, DIN/ISO-Compatible Calculation Method

507 Manufacturing Net-Shaped, Cold-Formed Gears (May 2008)

A net-shaped metal forming process has been developed for manufacturing quality, durable, high-yield and cost-efficient gears for high-volume production.

508 HMC Lassos World's Largest Gear Grinder (June 2008)

Hofler Rapid 6000 Makes North American Debut at Highway Machine Company.

509 Vacuum Carburizing Takes Center Stage (July 2008)

ALD-Holcroft Vacuum Technologies Co. will host a two-day technical symposium at the Henry Ford Museum in Dearborn, Michigan September 23– 24, 2008.

510 Volunteering is a Win-Win (August 2008)

Step forward now to help yourself and your industry.

511 Distortion Control by Innovative Heat Treating Technologies in the Automotive Industry (August 2008)

The proper control of distortion after thermal treatment of powertrain components in the automotive industry is an important measure in ensuring high-quality parts and minimizing subsequent hard machining processes in order to reduce overall production costs.

512 Determining Power Losses in the Helical Gear Mesh (September/October 2005)

This article reviews mathematical models for individual components associated with power losses, such as windage, churning, sliding and rolling friction losses.

513 Influence of Grinding Burn on Pitting Capacity (August 2008)

This paper intends to determine the load-carrying capacity of thermally damaged parts under rolling stress. Since inspection using real gears is problematic, rollers are chosen as an acceptable substitute. The examined scope of thermal damage from hard finishing extends from undamaged, best-case parts to a rehardening zone as the worst case. Also, two degrees of a tempered zone have been examined.

514 The Business of Going Green (August 2008)

Heat treatment industry reinforces environmental/energy conservation.

515 The Staying Power of Low-Pressure Carburizing (September/October 2008)

Open any heat treating journal today and you’re certain to find multiple references (articles, technical papers and/or advertisements) promoting low-pressure carburizing (LPC). The uninformed might breeze by these references thinking it’s the next flash-in-the-pan, but unlike in the past, this time the process has legs.

516 NASA Gets Down and Dirty for SARJ Solution (September/October 2008)

For more than 10 months, NASA ground engineers and International Space Station (ISS) astronauts have been struggling with a perplexing malfunction of one of the station’s two solar array rotary joints (SARJ).

517 Induction Hardening of Gears and Critical Components - Part I (September/October 2008)

Induction hardening is a heat treating technique that can be used to selectively harden portions of a gear, such as the flanks, roots and tips of teeth, providing improved hardness, wear resistance, and contact fatigue strength without affecting the metallurgy of the core and other parts of the component that don’t require change. This article provides an overview of the process and special considerations for heat treating gears. Part I covers gear materials, desired microsctructure, coil design and tooth-by-tooth induction hardening.

518 Innovative Analysis and Documentation of Gear Test Results (September/October 2008)

In this paper, a method is presented for analyzing and documenting the pitting failure of spur and helical gears through digital photography and automatic computerized evaluation of the damaged tooth fl ank surface. The authors have developed an accurate, cost-effective testing procedure that provides an alternative to vibration analysis or oil debris methods commonly used in conjunction with similar test-rig programs.

519 Lapping and Superfinishing Effects on Surface Finish of Hypoid Gears and Transmission Errors (September/October 2008)

This presentation is an expansion of a previous study (Ref.1) by the authors on lapping effects on surface finish and transmission errors. It documents the effects of the superfinishing process on hypoid gears, surface finish and transmission errors.

520 Where Are We Now (January/February 2010)

The struggles of the manufacturing economy in 2009 are well documented. Even among those of us with long careers, most of us have never seen activity come to a screeching halt the way it did last year. 2009 was tough on all of us. So, what should we expect in 2010?

521 All-in-One Broaching Capability (January/February 2010)

Faster, more efficient manufacturing offered with table-top design from American Broach & Machine.

522 Producing Profile and Lead Modifications in Threaded Wheel and Profile Grinding (January/February 2010)

Modern gearboxes are characterized by high torque load demands, low running noise and compact design. In order to fulfill these demands, profile and lead modifications are being applied more often than in the past. This paper will focus on how to produce profile and lead modifications by using the two most common grinding processes—threaded wheel and profile grinding. In addition, more difficult modifications—such as defined flank twist or topological flank corrections—will also be described in this paper.

523 Global Positioning System: The Early Years (January/February 2010)

Before retiring from St. Louis Gear in 2000, Roy Harmon liked to tinker. Since the customer base at the time was seasonal, Harmon was looking for a project to keep himself busy. The engineer decided to challenge himself by designing a “South Pointing Chariot,” a device he had read about in the book The Evolution of the Gear Art by Darle Dudley.

524 Crowning: A Cheap Fix for Noise and Misalignment Problems (March/April 2010)

Fred Young, CEO of Forest City Gear, talks about sophisticated gear manufacturing methods and how they can help solve common gear-related problems.

525 Gear Finishing with a Nylon Lap (September/October 2005)

The objective of this research is to develop a new lapping process that can efficiently make tooth flanks of hardened steel gears smooth as a mirror.

526 Systematic Investigations on the Influence of Case Depth on the Pitting and Bending Strength of Case Carburized Gears (July/August 2005)

The gear designer needs to know how to determine an appropriate case depth for a gear application in order to guarantee the required load capacity.

527 New Developments in Gear Hobbing (March/April 2010)

Several innovations have been introduced to the gear manufacturing industry in recent years. In the case of gear hobbing—the dry cutting technology and the ability to do it with powder-metallurgical HSS—might be two of the most impressive ones. And the technology is still moving forward. The aim of this article is to present recent developments in the field of gear hobbing in conjunction with the latest improvements regarding tool materials, process technology and process integration.

528 The Effects of Pre-Rough Machine Processing on Dimensional Distortion During Carburizing (September/October 2006)

A study was conducted to isolate the influence of pre-rough machine processing on final dimensional distortion.

529 Shorter Cycle Times for Carburizing (March/April 2006)

Dana Corp. is developing a process that carburizes a straight bevel gear to a carbon content of 0.8% in 60 fewer minutes than atmosphere carburizing did with an identical straight bevel.

530 Medical Device Manufacturing Keeps Gear Industry Healthy (March/April 2006)

When Forest City Gear started manufacturing gears for medical components in the 1980s, it was a minuscule part of the company's business. Today, the medical device industry represents 18-20%.

531 What's the Right Tolerance (March/April 2006)

Charles Schultz of Brad Foote Gear Works discusses some of the finer points of engineering tolerances--and muscle cars.

532 Gleason's Genesis 130SV Gear Shaving Machine (May/June 2006)

The 130SV shaving machine from Gleason is the newest of the company's Genesis family of gear production equipment.

533 New Checker Scan-Measures Stick Blades with Ruby-Tipped Probes (May/June 2006)

This month, German automakers will receive the first three units of Klingelnberg's new automated blade checker designed for the shop floor.

534 Constant Innovation Keeps Suppliers to Race Car Manufacturers Earning Trophies (May/June 2006)

When the fans start screaming at the Daytona 500, they're cheering for Jeff Gordon. Only the die-hard racing fan can appreciate the gearing and engineering that goes into each race car.

535 Influence of Surface Roughness on Gear Pitting Behavior (May/June 2006)

In earlier studies, surface roughness has been shown to have a significant influence on gear pitting life. This paper discusses how high surface roughness introduces a wear mechanism that delays the formation of pits. Accompanied by a full-page technical review.

536 Tool Life and Productivity Improvement Through Cutting Parameter Setting and Tool Design in Dry High-Speed Bevel Gear Tooth Cutting (May/June 2006)

This article presents some of the findings of cutting investigations at WZL in which the correlation of cutting parameters, cutting materials, tool geometry and tool life have been determined.

537 Drake's Newest Thread Grinder Utilizes Robot Load-Unload System (July/August 2006)

The GS:TE-LM thread grinder from Drake Manufacturing is fitted with a robot load/unload system that provides maximum throughput for high-volume production of ground threads.

538 Generating Interchangeable 20-Degree Spur Gear Sets with Circular Fillets to Increase Load Carrying Capacity (July/August 2006)

This article presents a new spur gear 20-degree design that works interchangeably with the standard 20-degree system and achieves increased tooth bending strength and hence load carrying capacity.

539 The Lubrication of DLC Coated Gears with Environmentally Adapted Ester-Based Oil (July/August 2006)

A main limiting factor in extending the use of hard coatings to machine component application is the lack of knowledge about how these inert coatings perform under lubricated conditions using today's lubricants.

540 Gear Shaving - Process Simulation Helps to Comprehend an Incomprehensible Process (September/October 2006)

Due to its economical efficiency, the gear shaving process is a widely used process for soft finishing of gears. A simulation technique allows optimization of the process.

541 A Study on Reducing Gear Tooth Profile Error by Finish Roll Forming (July/August 2005)

The authors have developed a rack-type rolling process in which a rack tool is used to roll gear teeth. The results and analysis show that the proposed method reduces errors.

542 Optimization of the Gear Profile Grinding Process Utilizing an Analogy Process (November/December 2006)

In order to grind gears burn-free and as productively as possible, a better understanding of the process is required.

543 Holroyd Launches New Gear Grinder (January/February 2005)

New machine promises DIN 2 accuracy and unique features at low cost.

544 Events (January/February 2005)

The complete Events section from January/February 2005, including coverage of a vacuum carburizing conference.

545 Running Gear (January/February 2005)

The Addendum team has seen the future of running, and it's geared.

546 Environmentally Friendly Cutting Fluids (March/April 2005)

Environmentally friendly cutting fluids aren't just good for the environment. They can also be good for performance.

547 Advances in Quenching - A Discussion of Present and Future Technologies (March/April 2005)

Heat treating and quenching are arguably the most critical operations in the manufacture of gears. This article examines causes of distortion in heat treating and quenching.

548 Hot Stuff - Heat Treating News (March/April 2005)

The latest heat treating news from March/April 2005

549 The Heat Goes On - Gear Up for Induction Hardening (March/April 2005)

This article covers preventive maintenance and modification to machinery to induction harden different types of gear.

550 New Approaches in Roll Testing Technology of Spiral Bevel and Hypoid Gear Sets (May/June 2005)

This paper presents a new approach in roll testing technology of spiral bevel and hypoid gear sets on a CNC roll tester applying analytical tools, such as vibration noise and single-flank testing technology.

551 The Influence of Additive Chemistry on Micropitting (May/June 2005)

This article discusses the potential effects observed for different antiwear and EP chemistry on the micropitting of cylindrical gears.

552 Opportunities for Gear Grinders - Insights from the Machinery Front (July/August 2005)

Tom Lang of Kapp Technologies shares his views on the trends affecting ground gears.

553 Superfinishing Gears - The State of the Art, Part II (July/August 2005)

In a previous article, the authors identified two misconceptions surrounding gear superfinishing. Here, they tackle three more.

554 Why Vacuum Carburizing (March/April 2010)

Heat treat alternative offers advantages over conventional methods.

555 The Road Leads Straight to Hypoflex (March/April 2010)

A new method for cutting straight bevel gears.

556 Gear Manufacturing in the Far East (January/February 2006)

This article gives readers a glimpse of some companies that manufacture gears in the Far East. We've talked with more than a dozen companies in India, Taiwan and Korea...

557 Flank Load Carrying Capacity and Power Loss Reduction by Minimized Lubrication (May 2011)

The objective of this study was to investigate the limits concerning possible reduction of lubricant quantity in gears that could be tolerated without detrimental effects on their load carrying capacity.

558 Gear Shaving Basics, Part II (January/February 1998)

In our last issue, we covered the basic principles of gear shaving and preparation of parts for shaving. In this issue, we will cover shaving methods, design principles and cutter mounting techniques.

559 Zoller and Ingersoll Partner for Measuring Hob Cutters (March/April 2011)

With growing markets in aerospace and energy technologies, measuring hob cutters used in gear cutting is becoming an essential requirement for workpieces and machine tools. Zoller, a provider of solutions for tool pre-setters, measuring and inspection machines and tool management software, has developed a new partnership with Ingersoll/Germany for shop floor checking of hob cutters by a combined hardware and software approach.

560 Induction Heat Treating Gains Ground through Advances in Technology (March/April 2011)

In recent years, there has been significant interest in expanding the use of induction hardening in gear manufacturing operations. Over the past several years, many of the limits to induction hardening have shrunk, thanks to recent advances in technology, materials and processing techniques.

561 Grinding, Finishing and Software Upgrades Abound (March/April 2011)

Machine tool companies are expanding capabilities to better accommodate the changing face of manufacturing. Customers want smaller-sized equipment to take up less valuable floor space, multifunctional machines that can handle a variety of operations and easy set-up changes that offer simplified operation and maintenance.

562 Optimal Modifications of Gear Tooth Surfaces (March/April 2011)

In this paper a new method for the introduction of optimal modifications into gear tooth surfaces - based on the optimal corrections of the profile and diameter of the head cutter, and optimal variation of machine tool settings for pinion and gear finishing—is presented. The goal of these tooth modifications is the achievement of a more favorable load distribution and reduced transmission error. The method is applied to face milled and face hobbed hypoid gears.

563 The Gear Ring and Other Creative Anomalies (March/April 2011)

Interactive jewelry designed from micro-precision parts.

564 Robotic Gear Deburring System Automates Chamfering (November/December 2009)

Compass Automation unveiled its Robotic Deburring System at Gear Expo 2009.

565 Greenhouse of the Gear Industry (May 2011)

Publisher Michael Goldstein talks about how one gear company is encouraging young people in manufacturing. What are you doing?

566 Developing Flexible Couplings Standards (May 2011)

AGMA Flexible Couplings committee chairman Glenn C. Pokrandt gives an update about standards and other documents under development.

567 The Global Gear Industry - Insights, Projections, Facts and Figures (May 2011)

A series of short reports on global manufacturing growth and the gear industry's role.

568 Micropitting of Big Gearboxes: Influence of Flank Modification and Surface Roughness (May 2011)

Most research on micropitting is done on small-sized gears. This article examines whether those results are also applicable to larger gears.

569 An Emphasis on Accuracy (June/July 2011)

Meeting the many challenges of large gear inspection.

570 The Process of Gear Shaving (January/February 1986)

Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index, helical angle, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concentrations in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase the gear's load carrying capacity, its factor of safety and its service life.

571 Gear Hobbing Technology Update (June/July 2011)

Q&A with Liebherr's Dr. Alois Mundt.

572 Analysis and Testing of Gears with Asymmetric Involute Tooth Form and Optimized Fillet Form for Potential Application in Helicopter Main Drives (June/July 2011)

Gears with an asymmetric involute gear tooth form were analyzed to determine their bending and contact stresses relative to symmetric involute gear tooth designs, which are representative of helicopter main-drive gears.

573 Drive Line Analysis for Tooth Contact Optimization of High-Power Spiral Bevel Gears (June/July 2011)

In the majority of spiral bevel gears, spherical crowning is used. The contact pattern is set to the center of the active tooth flank and the extent of the crowning is determined by experience. Feedback from service, as well as from full-torque bench tests of complete gear drives, has shown that this conventional design practice leads to loaded contact patterns, which are rarely optimal in location and extent. Oversized reliefs lead to small contact area, increased stresses and noise, whereas undersized reliefs result in an overly sensitive tooth contact.

574 Manufacturing Method of Large-Sized Spiral Bevel Gears in Cyclo-Palloid System Using Multi-Axis Control and Multi-Tasking Machine Tool (August 2011)

In this article, the authors calculated the numerical coordinates on the tooth surfaces of spiral bevel gears and then modeled the tooth profiles using a 3-D CAD system. They then manufactured the large-sized spiral bevel gears based on a CAM process using multi-axis control and multi-tasking machine tooling. The real tooth surfaces were measured using a coordinate measuring machine and the tooth flank form errors were detected using the measured coordinates. Moreover, the gears were meshed with each other and the tooth contact patterns were investigated. As a result, the validity of this manufacturing method was confirmed.

575 State-of-the-Art Broaching (August 2011)

There are a number of companies working to change the way broaching is perceived, and over the past 10 years, they’ve incorporated significant technological changes to make the process more flexible, productive and accurate.

576 Reliable and Efficient Skiving (September 2011)

Klingelnberg's new tool and machine concept allow for precise production.

577 Real-World Job Training the Lean Way -- And Loving It (September 2011)

Make no mistake -- lean manufacturing is here to stay. And no wonder. As a fiercely competitive global economy continues to alter companies’ “Main Street” thinking, that relatively new dynamic is spurring the need for “I-need-it-yesterday” production output. And for increasingly more industries -- big or small -- that means getting as lean as you can, as fast as you can.

578 Size and Material Influence on the Tooth Root, Pitting, Scuffing and Wear Load-Carrying Capacity of Fine-Module Gears (September 2011)

In this study, limiting values for the load-carrying-capacity of fine-module gears within the module range 0.3–1.0 mm were determined and evaluated by comprehensive, experimental investigations that employed technical, manufacturing and material influence parameters.

579 Analysis of Load Distribution in Planet Gear Bearings (September 2011)

In epicyclic gear sets designed for aeronautical applications, planet gears are generally supported by spherical roller bearings with the bearing outer race integral to the gear hub. This article presents a new method to compute roller load distribution in such bearings where the outer ring can’t be considered rigid.

580 Heat Treat Society (September 2011)

Co-located ASM and AGMA shows are a hot ticket.

581 2011 AGMA Fall Technical Meeting (September 2011)

The AGMA Fall Technical Meeting provides an opportunity to share ideas with others on the design, analysis, manufacturing and application of gears, gear drives, and related products, as well as associated processes and procedures.

582 LMT Fette Introduces SpeedCore (October 2011)

New material technology allows for more efficient and flexible hobbing.

583 Gear Shaving Basics, Part I (November/December 1997)

Gear shaving is a free cutting gear finishing operation which removes small amounts of metal from the working surfaces of gear teeth. Its purpose is to correct errors in index, helix angle, tooth profile and eccentricity.

584 Gear Finishing by Shaving, Rolling and Honing, Part II (May/June 1992)

Part I of this series focused on gear shaving, while Part II focuses on gear finishing by rolling and honing.

585 High-Temperature Testing of Stanyl Plastic Gears: A Comparison with Tensile Fatigue Data (March/April 2010)

This paper shows an experimental study on the fatigue lifetime of high-heat polyamide (Stanyl) gears running in oil at 140°C. Based on previous works (Refs. 1–2), an analysis is made correcting for tooth bending and calculating actual root stresses. A comparison with tensile bar fatigue data for the same materials at 140°C shows that a good correlation exists between gear fatigue data and tensile bar fatigue data. This insight provides a solid basis for gear designers to design plastic gears using actual material data.

586 Effects of Profile Corrections on Peak-to-Peak Transmission Error (July 2010)

Profile corrections on gears are a commonly used method to reduce transmission error, contact shock, and scoring risk. There are different types of profile corrections. It is a known fact that the type of profile correction used will have a strong influence on the resulting transmission error. The degree of this influence may be determined by calculating tooth loading during mesh. The current method for this calculation is very complicated and time consuming; however, a new approach has been developed that could reduce the calculation time.

587 Shot Peening Up Close and Personal (March/April 2010)

U.S. Shot Peening and Blast Cleaning Workshop.

588 Building on Your Foundation (May 2010)

When you graduated from school and made your way into the world, you probably thought you’d learned everything you needed to know to be successful. But those of us who’ve been out in the workforce for some time know that you never stop learning.

589 Your Tax Dollars at Work: U.S. Commerce Department, Your Boots on the Ground Overseas (May 2010)

Easily one of the central issues affecting U.S. manufacturing is what one might call the exports deficit—the inability of American companies to sell products to, for instance, Asian markets, developing countries and other ports of call—due to what they perceive to be unfair trade agreements and or policies.

590 Software-Based Process Design in Gear Finish Hobbing (May 2010)

In this paper, the potential for geometrical cutting simulations - via penetration calculation to analyze and predict tool wear as well as to prolong tool life - is shown by means of gear finish hobbing. Typical profile angle deviations that occur with increasing tool wear are discussed. Finally, an approach is presented here to attain improved profile accuracy over the whole tool life of the finishing hob.

591 Allowable Contact Stresses in Jacking Gear Units Used in the Offshore Industry (May 2010)

An offshore jack-up drilling rig is a barge upon which a drilling platform is placed. The barge has legs that can be lowered to the sea floor to support the rig. Then the barge can be “jacked up” out of the water, providing a stable work platform from which to drill for oil and gas. Jack-up drilling rigs were first introduced in the late 1950s. Rack-and- pinion-type jack-up units were introduced soon after that and have dominated the industry ever since.

592 Faster Honing to Mirror Fishises on Gear Faces and Bores (June 2010)

Stringent NVH requirements, higher loads and the trend towards miniaturization to save weight and space are forcing transmission gear designers to increasingly tighten the surface finish, bore size and bore-to-face perpendicularity tolerances on the bores of transmission gears.

593 Single-Pass Honing Holds the Line on PM Sprockets (June 2010)

Bore finishing system from Sunnen helps Cloyes Gear and Products achieve high accuracy, productivity and process capability.

594 Hard Turning Large-Diameter Parts (June 2010)

Fuji's VTP-1000 is designed for highly accurate fine finishing of cylindrical components up to one meter in diameter.

595 Variation Analysis of Tooth Engagement and Load Sharing in Involute Splines (June 2010)

Involute spline couplings are used to transmit torque from a shaft to a gear hub or other rotating component. External gear teeth on the shaft engage an equal number of internal teeth in the hub. Because multiple teeth engage simultaneously, they can transmit much larger torques than a simple key and keyway assembly. However, manufacturing variations affect the clearance between each pair of mating teeth, resulting in only partial engagement.

596 The Anatomy of a Micropitting-Induced Tooth Fracture Failure (June 2010)

Micropitting has become a major concern in certain classes of industrial gear applications, especially wind power and other relatively highly loaded, somewhat slow-speed applications, where carburized gears are used to facilitate maximum load capacity in a compact package. While by itself the appearance of micropitting does not generally cause much perturbation in the overall operation of a gear system, the ultimate consequences of a micropitting failure can, and frequently are, much more catastrophic.

597 Improved Inspection Software Helps Provide Optimum Cutting Results (July 2010)

Klingelnberg measuring centers eliminate trial-and-error with modern analysis tools.

598 Crowning Techniques in Aerospace Actuation Gearing (August 2010)

One of the most effective methods in solving the edge loading problem due to excess misalignment and deflection in aerospace actuation gearing is to localize tooth-bearing contact by crowning the teeth. Irrespective of the applied load, if the misalignment and/or deflection are large enough to cause the contact area to reduce to zero, the stress becomes large enough to cause failure. The edge loading could cause the teeth to break or pit, but too much crowning may also cause the teeth to pit due to concentrated loading. In this paper, a proposed method to localize the contact bearing area and calculate the contact stress with crowning is presented and demonstrated on some real-life examples in aerospace actuation systems.

599 Gear Finishing by Shaving, Rolling and Honing, Part I (March/April 1992)

There are several methods available for improving the quality of spur and helical gears following the standard roughing operations of hobbing or shaping. Rotary gear shaving and roll-finishing are done in the green or soft state prior to heat treating.

600 Building Repeat Business: What Gear Buyers Really Want from Gear Manufacturers (August 2010)

In this article, gear buyers have been given an opportunity to discuss quality, value, customer service and how gear manufacturers can improve business practices.

601 Gear Fault Detection Effectiveness as Applied to Tooth Surface Pitting Fatigue Damage (November/December 2010)

A study was performed to evaluate fault detection effectiveness as applied to gear-tooth pitting-fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets of spur pinion and face gears run during a previous endurance evaluation study.

602 The Effect of Straight-Sided Hob Teeth (November/December 2010)

It is well known that hobs with straight-sided teeth do not cut true involutes. In this paper, the difference between the straight side of a hob tooth and the axial profile of an involute worm is evaluated. It is shown that the difference increases as the diametral pitch increases, to the extent that for fine-pitch gearing, the difference is insignificant.

603 Technically Speaking, a Huge Success (November/December 2010)

A recap of the AGMA 2010 Fall Technical Meeting.

604 Protecting Our Own (January/February 2011)

Publisher Michael Goldstein discusses the loss of U.S. manufacturing capability and what we should do about it.

605 Writing the Standards (January/February 2011)

Gary A. Bish, director of product design technology for Horsburgh & Scott, discusses his role as chairman of the AGMA mill gearing committee.

606 Gear Chamfering Robot (January/February 2011)

Banyan Technologies introduces a robotic chamfering device suitable for deburring, chamfering and radiusing the edges of slew bearing ring gears.

607 Big Gears Better and Faster (January/February 2011)

Indexable carbide insert cutting tools for gears are nothing new. But big gears have recently become a very big business. The result is that there's been a renewed interest in carbide insert cutting tools.

608 Point-Surface-Origin Macropitting Caused by Geometric Stress Concentration (January/February 2011)

Point-surface-origin (PSO) macropitting occurs at sites of geometric stress concentration (GSC) such as discontinuities in the gear tooth profile caused by micropitting, cusps at the intersection of the involute profile and the trochoidal root fillet, and at edges of prior tooth damage, such as tip-to-root interference. When the profile modifications in the form of tip relief, root relief, or both, are inadequate to compensate for deflection of the gear mesh, tip-to-root interference occurs. The interference can occur at either end of the path of contact, but the damage is usually more severe near the start-of-active-profile (SAP) of the driving gear.

609 Spiral Bevel Gears: Tribology Aspects in Angular Transmission Systems, Part IV (January/February 2011)

This article is part four of an eight-part series on the tribology aspects of angular gear drives. Each article will be presented first and exclusively by Gear Technology, but the entire series will be included in Dr. Stadtfeld’s upcoming book on the subject, which is scheduled for release in 2011.

610 Now, More than Ever - Gear Training (January/February 2011)

Gear education and training are vital to sellers, buyers and national security. This article explores gear training options available in the USA.

611 Gear Training - Courses, Schedules, Rates and More (January/February 2011)

The following article provides details on the specific programs and learning opportunities discussed in the January/February 2011 article "Now, More Than Ever" by senior editor Jack McGuinn.

612 Kinematical Simulation of Face Hobbing Indexing and Tooth Surface Generation of Spiral Bevel and Hypoid Gears (January/February 2006)

In addition to the face milling system, the face hobbing process has been developed and widely employed by the gear industry. However, the mechanism of the face hobbing process is not well known.

613 Finish Hobbing Crowned Helical Gears without Twist (January/February 2006)

New tool from LMT-Fette provides combination of operations.

614 ASM Booth Previews (October 2011)

Here are some of the new products and technologies available to attendees at Heat Treat 2011.

615 Gear Milling on Non-Gear Dedicated Machinery (July 2009)

Imagine the flexibility of having one machine capable of milling, turning, tapping and gear cutting with deburring included for hard and soft material. No, you’re not in gear fantasy land. The technology to manufacture gears on non gear-dedicated, mult-axis machines has existed for a few years in Europe, but has not yet ventured into mainstream manufacturing. Deckel Maho Pfronten, a member of the Gildemeister Group, took the sales plunge this year, making the technology available on most of its 2009 machines.

616 New Potentials in Carbide Hobbing (January/February 2004)

To meet the future goals of higher productivity and lower production costs, the cutting speeds and feeds in modern gear hobbing applications have to increase further. In several cases, coated carbide tools have replaced the commonly used high speed steel (HSS) tools.

617 Innovative Concepts for Grinding Wind Power Energy Gears (June 2009)

This article shows the newest developments to reduce overall cycle time in grinding wind power gears, including the use of both profile grinding and threaded wheel grinding.

618 Superfinishing Gears -- The State of the Art (November/December 2003)

Superfinishing the working surfaces of gears and their root fillet regions results in performance benefits.

619 Gear Grinding 2003 (November/December 2003)

The benefits of ground gears are well known. They create less noise, transmit more power and have longer lives than non-ground gears. But grinding has always been thought of as an expensive process, one that was necessary only for aerospace or other high-tech gear manufacturing.

620 A Whodunnit in Gearbox Failure (November/December 2008)

Forensics isn't just for tough-talking, crime-busting scientists--most commonly found on your television; the tactic also holds the key to successful gearbox design and manufacture.

621 Green Heat Treating - No Sweat (November/December 2009)

Bob McCulley of Comprehensive Heat Treat Specialists describes how even the most energy intensive industrial processes can be made "green."

622 Bending Fatigue Tests of Helicopter Case Carburized Gears: Influence on Material, Design and Manufacturing Parameters (November/December 2009)

A single tooth bending (STB) test procedure has been developed to optimally map gear design parameters. Also, a test program on case-carburized, aerospace standard gears has been conceived and performed in order to appreciate the influence of various technological parameters on fatigue resistance and to draw the curve shape up to the gigacycle region.

623 Sigma Pool Encourages Collaboration at 2009 U.S. Gear Seminar (July 2009)

In the past, the coffee breaks and dinner events at Sigma Pool’s gear seminars have often triggered future process development and product improvements. This was still the case during the 2009 installment where customers and suppliers talked shop inside and outside the banquet hall on the new market and technology challenges currently facing the gear industry.

624 Product News (May 2009)

The complete Product News section from the May 2009 issue of Gear Technology.

625 Hob Tool Life Technology Update (March/April 2009)

The method of cutting teeth on a cylindrical gear by the hobbing process has been in existence since the late 1800s. Advances have been made over the years in both the machines and the cutting tools used in the process. This paper will examine hob tool life and the many variables that affect it. The paper will cover the state-of-the-art cutting tool materials and coatings, hob tool design characteristics, process speeds and feeds, hob shifting strategies, wear characteristics, etc. The paper will also discuss the use of a common denominator method for evaluating hob tool life in terms of meters (or inches) per hob tooth as an alternative to tool life expressed in parts per sharpening.

626 An Investigation of the Influence of Shaft Misalignment on Bending Stresses of Helical Gears with Lead Crown (November/December 2008)

In this study, the combined influence of shaft misalignments and gear lead crown on load distribution and tooth bending stresses is investigated. Upon conclusion, the experimental results are correlated with predictions of a gear load distribution model, and recommendations are provided for optimal lead crown in a given misalignment condition.

627 Anchors Aweigh (March/April 2004)

Fred Young, president of Forest City Gear in Roscoe, Illinois, discovered a new market on a flyfishing trip on the White River in Arkansas.

628 The Capacity of Superfinished Vehicle Components to Increase Fuel Economy, Part I (January/February 2009)

This paper will present data from both laboratory and field testing demonstrating that superfinished components exhibit lower friction, operating temperature, wear and/ or higher horsepower, all of which translate directly into increased fuel economy.

629 Remedies for Cutting Edge Failure of Carbide Hob due to Chip Crush (November/December 2004)

Some results of evaluation by this method in the automotive industry.

630 Gear Shaping Machines CNC Developement (November/December 1985)

Up until approximately 1968-69, pinion cutter-type gear shaping machines had changed very little since their conception in the early 1900's.

631 Technological Fundamentals of CBN Bevel Gear Finish Grinding (November/December 1985)

The bevel gear grinding process, with conventional wheels, has been limited to applications where the highest level of quality is required.

632 General Equations for Gear Cutting Tool Calculations (November/December 1985)

The proper design or selection of gear cutting tools requires thorough and detailed attention from the tool designer. In addition to experience, intuition and practical knowledge, a good understanding of profile calculations is very important.

633 Single Flank Data Analysis and Interpretation (September/October 1985)

Much of the information in this article has been extracted from an AGMA Technical Paper, &quot;What Single Flank Testing Can Do For You&quot;, presented in 1984 by the author

634 Hob Length Effects (September/October 1985)

Hobbing is probably the most popular gear manufacturing process. Its inherent accuracy and productivity makes it a logical choice for a wide range of sizes.

635 Grinding Gears for Racing Transmissions (September/October 2009)

When you push 850 horsepower and 9,000 rpm through a racing transmission, you better hope it stands up. Transmission cases and gears strewn all over the racetrack do nothing to enhance your standing, nor that of your transmission supplier.

636 Dynamic Analysis of Straight and Involute Tooth Form (July/August 1985)

The effect of load speed on straight and involute tooth forms is studied using several finite-element models.

637 Winds of Change in Profile Grinding (May/June 2004)

Recent breakthroughs in profile grinding software are helping Anderson Precision Gears and others meet wind power’s insatiable appetite for faster production of large, high-quality gears.

638 Cutting Edge Grinders Are Great - But How's Your Workholding (March/April 2009)

Capacity is key today, and the best way to ensure that you are squeezing every dime out of that new machine is to complement it with innovative workholding.

639 Application of the First International Calculation Method for Micropitting (May 2012)

The first edition of the international calculation method for micropitting—ISO TR 15144–1:2010—was just published last December. It is the first and only official, international calculation method established for dealing with micropitting. Years ago, AGMA published a method for the calculation of oil film thickness containing some comments about micropitting, and the German FVA published a calculation method based on intensive research results. The FVA and the AGMA methods are close to the ISO TR, but the calculation of micropitting safety factors is new.

640 Grinding Induced Changes in Residual Stresses of Carburized Gears (March/April 2009)

This paper presents the results of a study performed to measure the change in residual stress that results from the finish grinding of carburized gears. Residual stresses were measured in five gears using the x-ray diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory.

641 Low Pressure Carburizing of Large Transmission Parts (September/October 2009)

Often, the required hardness qualities of parts manufactured from steel can only be obtained through suitable heat treatment. In transmission manufacturing, the case hardening process is commonly used to produce parts with a hard and wear-resistant surface and an adequate toughness in the core. A tremendous potential for rationalization, which is only partially used, becomes available if the treatment time of the case hardening process is reduced. Low pressure carburizing (LPC) offers a reduction of treatment time in comparison to conventional gas carburizing because of the high carbon mass flow inherent to the process (Ref. 1).

642 Effects of Gear Surface Parameters on Flank Wear (January/February 2009)

Non-uniform gear wear changes gear topology and affects the noise performance of a hypoid gear set. The aggregate results under certain vehicle driving conditions could potentially result in unacceptable vehicle noise performance in a short period of time. This paper presents the effects of gear surface parameters on gear wear and the measurement/testing methods used to quantify the flank wear in laboratory tests.

643 Service Behavior of PVD-Coated Gearing Lubricated with Biodegradable Synthetic Ester Oils (January/February 2004)

The following article is concerned with the analysis of the wear-reducing effect of PVD-coatings in gearings. Standardized test methods are used, which under near-real conditions enable statements to be made about the different forms of damage and wear (micropitting, macropitting, scuffing).

644 High-Performance Sintered-Steel Gears for Transmissions and Machinery: A Critical Review (August 2012)

Except for higher-end gear applications found in automotive and aerospace transmissions, for example, high-performance, sintered-steel gears match wrought-steel gears in strength and geometrical quality. The enhanced P/M performance is due largely to advances in powder metallurgy over last two decades, such as selective surface densification, new materials and lubricants for high density and warm-die pressing. This paper is a review of the results of a decade of research and development of high- performance, sintered-steel gear prototypes.

645 Tolerance for Overload Stress (March/April 1985)

The performance of carburized components can be improved simply by changing the alloy content of the steel.

646 High Performance Gears Using Powder Metallurgy (PM) Technology (November/December 2004)

Powder metallurgy (P/M) techniques have proven successful in displacing many components within the automobile drive train, such as: connecting rods, carriers, main bearing caps, etc. The reason for P/M’s success is its ability to offer the design engineer the required mechanical properties with reduced component cost.

647 The Powder Metal Method (June 2008)

Despite economic uncertainty, the future looks promising for PM Gears.

648 PM Community Gathers for Annual Event (August 2010)

The metal powder industry gathered in force this past June for PowderMet 2010, the 2010 International Conference on Powder Metallurgy and Particulate Materials.

649 Gear Material Risks and Rewards (August 2011)

Technology investments lead to product innovation at gear materials suppliers.

650 Austempered Ductile Iron: Technology Base Required for an Emerging Technology (October/November 1984)

This paper addresses Austempered Ductile Iron (ADI) as an emerging Itechnology and defines its challenge by describing the state-of-the-art of incumbent materials. The writing is more philosophical in nature than technical and is presented to establish a perspective.

651 The Beginner's Guide to Powder Metal Gears (September/October 1995)

Increasingly gear designers and product engineers are capitalizing on the economic advantages of powder metallurgy (P/M) for new and existing gear applications. Powder metal gears are found in automobiles, outdoor power equipment transmissions and office machinery applications as well as power hand tools, appliances and medial components.

652 Comparison of Surface Durability & Dynamic Performance of Powder Metal & Steel Gears (September/October 1995)

Surface-hardened, sintered powder metal gears are increasingly used in power transmissions to reduce the cost of gear production. One important problem is how to design with surface durability, given the porous nature of sintered gears. Many articles have been written about mechanical characteristics, such as tensile and bending strength, of sintered materials, and it is well-known that the pores existing on and below their surfaces affect their characteristics (Refs. 1-3). Power transmission gears are frequently employed under conditions of high speed and high load, and tooth surfaces are in contact with each other under a sliding-rolling contact condition. Therefore it is necessary to consider not only their mechanical, but also their tribological characteristics when designing sintered gears for surface durability.

653 Noise Reduction in Plastic & Powder Metal Gear Sets (July/August 1996)

The data discussed in this article was taken from an upright vacuum cleaner. This was a prototype cleaner that was self-propelled by a geared transmission. It was the first time that the manufacturer had used a geared transmission in this application.

654 AGMA & MPIF Develop Standards, Information Sheet for Powder Metal Gears (September/October 1996)

AGMA and members of the Metal Powder Industries Federation (MPIF) are three years into a joint project to develop specifications and an information sheet on rating powder metal gears. According to committee vice chairman Glen A. Moore of Burgess-Norton Mfg. Co., the first phase of the project, the publication of AGMA Standard "6009-AXX, Specifications for Powder Metallurgy Gears," should be completed in late 1996 or early 1997.

655 Powder Metallurgy Innovations (September/October 1999)

Powder metal. To gear makers today, the phrase conjures images of low power applications in non-critical systems. As powder metal technology advances, as the materials increase in density and strength, such opinions are changing. It is an ongoing, evolutionary process and one that will continue for some time. According to Donald G. White, the executive director of the Metal Powder Industries Federation, in his State-of-the-P/M Industry - 1999 report. "The P/M world is changing rapidly and P/M needs to be recognized as a world-class process - national, continental and even human barriers and prejudices must be eliminated - we must join forces as a world process - unified in approach and goals."

656 Automotive Transmission Design Using Full Potential of Powder Metal (August 2013)

For metal replacement with powder metal (PM) of an automotive transmission, PM gear design differs from its wrought counterpart. Indeed, complete reverse-engineering and re-design is required so to better understand and document the performance parameters of solid-steel vs. PM gears. Presented here is a re-design (re-building a 6-speed manual transmission for an Opel Insignia 4-cylinder, turbocharged 2-liter engine delivering 220 hp/320 N-m) showing that substituting a different microgeometry of the PM gear teeth -- coupled with lower Young’s modulus -- theoretically enhances performance when compared to the solid-steel design.

657 NASA's Return to Flight (May 2007)

Gear specialists at the NASA Glenn Research facility helped determine it was safe for the space shuttle to fly again.

658 Metallurgical Investigation of Tiger Stripes on a Carburized High Speed Pinion (May 2014)

Tiger stripes on a high-speed pinion made of a carburized SAE 9310 steel were investigated. The morphology of the damage was typical of electric discharge damage. The cause of the stripes and potential damage to the gear tooth were analyzed and are presented in this report.

659 Product News (July 2014)

The complete Product News section from the July 2014 issue of Gear Technology.

660 Product News (November/December 2016)

News about new Products in the Industry

661 What's New and Noteworthy in Powder Metal (September/October 2017)

First, the facts: powder metallurgy is a cost-effective method of forming precision net-shape metal components that allows for more efficiently designed products. It saves valuable raw materials through recycling and the elimination of costly secondary-machining. PM competes with wrought steel gears as the technology continues to advance. You'll find PM components in everything from automobile transmissions to aircraft turbine engines, surgical equipment and power tools.

662 NVH Potential of PM Gears for Electrified Drivetrains (September/October 2018)

Electrification has already started to have a noticeable impact on the global automotive industry. As a result, the drivetrains of hybrid (HEV) and full electric vehicles (EV) are facing many challenges, like increased requirements for NVH in high speed e-Drives and the need for performance improvements to deal with recuperation requirements. Motivated by the positive validation results of surface densified manual transmission gears which are also applicable for dedicated hybrid transmissions (DHTs) like e-DCTs, GKN engineers have been looking for a more challenging application for PM gears within those areas.

663 Powder Metal Through the Process Steps (September/October 2018)

Powder metal (PM) gears normally sell due to the lower cost and their relatively high mechanical performance. The reason behind the lower cost is that most of the machining is omitted due to the net-shape forming process. So how net-shape are powder metal gears? In this article some hard-to-find information about the tolerances through the manufacturing steps will be presented.

664 Product News (November/December 2018)

The latest product news for the gear industry, including new products and services from Gleason, Liebherr, Forest City Gear, GMTA, Starrett and Kennametal.

665 Product News (January/February 2019)

The complete Product News section from the January/February issue of Gear Technology.

666 Product News (November/December 2019)

The complete Product News section from the November/December 2019 issue of Gear Technology.

667 Product News (January/February 2020)

Integrated Production Chains from Kapp Niles, an alternative to press quenching from Seco/Warwick, an expansion of the Profilator line and more.

668 Optimal Polymer Gear Design: Metal-to-Plastic Conversion (May 2020)

Nowadays, the progress in polymer materials and injection molding processing has enabled a drastic expansion of plastic gear applications. They are used not only for lightly loaded motion transmissions, but also in moderately loaded power drives in automotive, agriculture, medical, robotics, and many other industries.

669 Industry News (June 2020)

The complete Industry News section from the June 2020 issue of Gear Technology.

670 An Innovative Way of Designing Gear Hobbing Processes (May 2012)

In today’s manufacturing environment, shorter and more efficient product development has become the norm. It is therefore important to consider every detail of the development process, with a particular emphasis on design. For green machining of gears, the most productive and important process is hobbing. In order to analyze process design for this paper, a manufacturing simulation was developed capable of calculating chip geometries and process forces based on different models. As an important tool for manufacturing technology engineers, an economic feasibility analysis is implemented as well. The aim of this paper is to show how an efficient process design—as well as an efficient process—can be designed.

671 The Replacements - Taking Steps to Strengthen the Future Skilled Workforce (January/February 2009)

For years, politicians, educators and business leaders have generated various ideas to revitalize U.S. manufacturing and engineering. These include manufacturing initiatives, internal training programs and an emphasis on science, technology, engineering and mathematics (STEM) in the classroom. The declining expertise in these fields, however, continues to be a growing problem in every facet of manufacturing and engineering.

672 American Wera Profilator Introduces Scudding Process (January/February 2008)

Rolled out at EMO 2007, the Scudding process is a continuous cutting operation that uses a tool design similar to a helical shaper cutter. It can be used for a wide range of gear applications...

673 True Bending Stress in Spur Gears (August 2007)

In this paper, an accurate FEM analysis has been done of the “true” stress at tooth root of spur gears in the function of the gear geometry. The obtained results confirm the importance of these differences.

674 Understanding the Application: A Key to Economical Gearbox Purchases (November/December 2004)

On a highway, a compact pick-up truck struggles to tow a 30-foot boat up a steep grade. Inside the pick-up, the owner curses himself. He saved money leasing a smaller truck but sees now that he really needed a bigger, pricier vehicle, one suitable for this job.

675 Optimism in Wind Abounds (January/February 2009)

Big gears and wind turbines go together like bees and honey, peas and carrots, bread and butter and—well, you get the idea. Wind isn’t just big right now, it’s huge. The wind industry means tremendous things for the energy dependent world we live in and especially big things for gear manufacturers and other beleaguered American industries.

676 Simulation of Hobbing for Analysis of Cutting Edge Failure due to Chip Crush (September/October 2004)

There are great advantages in dry hobbing, not only for friendliness toward the environment, but also for increasing productivity and for decreasing manufacturing cost. Dry hobbing, however, often causes failures in hob cutting edges or problems with the surface quality of gear tooth flanks. These difficulties are not present when hobbing with cutting oil. Pinching and crushing of generated chips between the hob cutting edge and the work gear tooth flank is considered a major cause of those problems.

677 Hot Stuff - Heat Treating News (March/April 2004)

News from around the world about heat treating.

678 Big Gears - High Standards, High Profits (January/February 2009)

Natural resources—minerals, coal, oil, agricultural products, etc.—are the blessings that Mother Earth confers upon the nations of the world. But it takes unnaturally large gears to extract them.

679 Steadfast and Streamlined: Can Lean Soften the Economic Blow (August 2009)

Two high-volume gear production cells grace the shop floor at Delta Research Corporation in Livonia, Michigan. Thanks to lean manufacturing, these cells have never shipped a defective part to a customer since they were developed over three years ago.

680 ASM Bringing the Heat to Gear Expo (July 2009)

Gear making and heat treating pair together like a fine cabernet and filet mignon. Now for the first time, the two industries are embracing this symbiotic relationship by co-locating their industry events this fall in Indianapolis. ASM International’s 2009 Heat Treating Society Conference and Exposition and Gear Technology’s favorite trade show, Gear Expo, are teaming up September 14–17 at the Indiana Convention Center in Indianapolis.

681 Computer Aided Design (CAD) of Forging and Extrusion Dies for the Production of Gears by Forming (January/February 1985)

Material losses and long production times are two areas of conventional spur and helical gear manufacturing in which improvements can be made. Metalforming processes have been considered for manufacturing spur and helical gears, but these are costly due to the development times necessary for each new part design. Through a project funded by the U.S. Army Tank - Automotive Command, Battelle's Columbus Division has developed a technique for designing spur and helical gear forging and extrusion dies using computer aided techniques.

682 A Model of the Pumping Action Between the Teeth of High-Speed Spur and Helical Gears (May/June 2004)

For a high-speed gearbox, an important part of power losses is due to the mesh. A global estimation is not possible and an analytical approach is necessary with evaluations of three different origins of power losses: friction in mesh contact, gear windage and pumping effect between teeth.

683 2007 Fall Technical Meeting Schedule of Events (August 2007)

Listing of papers to be presented and activities for the 2007 AGMA Fall Technical Meeting.

684 New Vacuum Processes (August 2007)

This paper introduces new process developments in low-pressure carburizing and carbonitriding using either high-pressure gas quenching or interrupted gas quenching.

685 Captive vs. Commercial Heat Treaters? A Split Decision (August 2007)

Heat treating is a vital step in the gear making process—that’s a given. But how that step is taken can happen in a number of ways.

686 Surface Damage Caused by Gear Profile Grinding and its Effects on Flank Load Carrying Capacity (September/October 2004)

Instances of damage to discontinuous form ground and surface-hardened gears, especially of large scale, have recently increased. This may be attributed partly to a faulty grinding process with negative effects on the surface zones and the surface properties.

687 The New Freedoms: Bevel Blades (September/October 2007)

Today, because of reduced cost of coatings and quicker turnaround times, the idea of all-around coating on three-face-sharpened blades is again economically viable, allowing manufacturers greater freedoms in cutting blade parameters, including three-face-sharpened and even four-face-sharpened blades.

688 Tooth-Bending Effects in Plastic Spur Gears (September/October 2007)

This paper describes the investigation of a steel-and-plastic gear transmission and presents a new hypothesis on the governing mechanism in the wear of plastic gears.

689 Design of Oil-Lubricated Machine Components for Life and Reliability (November/December 2007)

This article summarizes the use of laboratory fatigue data for bearings and gears coupled with probabilistic life prediction and EHD theories to predict the life and reliability of a commercial turboprop gearbox.

690 Optimal Choice of the Shaft Angle for Involute Hobbing (November/December 2007)

With reference to the machining of an involute spur or helical gear by the hobbing process, this paper suggests a new criterion for selecting the position of the hob axis relative to the gear axis.

691 Asymmetric Teeth: Bending Stress Calculation (March/April 2007)

This article includes a brief summary of the characteristics of involute asymmetric teeth and the problems connected with the related bending tests.

692 Forest City Puts Teeth in Competitive Strategy with Sunnen's Bore Honing Machine (March/April 2007)

Forest City Gear president Fred Young has a straightforward strategy for acquiring and retaining business...

693 Bowling for Gears (March/April 2007)

Here's what Dennis was thinking...

694 Help Wanted: Gear Company Seeks Perfect Machinist (January/February 2007)

Sales are up and it's time to hire some additional gear manufacturing personnel. Let's see--what qualities are wee looking for in the ideal candidates?

695 Challenges and Opportunities in the Gear Industry (January/February 2007)

We asked Fred Young, president of Forest City Gear Co., to answer some of the gear industry's burning questions.

696 Labor Pains in the American Gear Industry--Any Relief in Sight (January/February 2007)

Lack of skilled workers mirrors U.S. manufacturing's decline.

697 On-Site or Online, AGMA Teaches Gear Basics and Beyond (January/February 2007)

Despite the many things being done to promote manufacturing nationwide, there still remains an acute need for gear-specific training, remedial or otherwise.

698 Where Manufacturing and Education Mesh (January/February 2007)

But associations and grassroots organizations lack public awareness.

699 The Effect of Manufaturing Microgeometry Variations on the Load Distribution Factor and on Gear Contact and Root Stresses (July 2009)

Traditionally, gear rating procedures consider manufacturing accuracy in the application of the dynamic factor, but only indirectly through the load distribution are such errors in the calculation of stresses used in the durability and gear strength equations. This paper discusses how accuracy affects the calculation of stresses and then uses both statistical design of experiments and Monte Carlo simulation techniques to quantify the effects of different manufacturing and assembly errors on root and contact stresses.

700 Low Pressure Carburizing with High Pressure Gas Quenching (March/April 2004)

High demands for cost-effectiveness and improved product quality can be achieved via a new low pressure carburizing process with high pressure gas quenching. Up to 50% of the heat treatment time can be saved. Furthermore, the distortion of the gear parts could be reduced because of gas quenching, and grinding costs could be saved. This article gives an overview of the principles of the process technology and the required furnace technology. Also, some examples of practical applications are presented.

701 Repair via Isotropic Superfinishing of Aircraft Transmission Gears (May 2009)

The objective of this paper is to demonstrate that transmission gears of rotary-wing aircraft, which are typically scrapped due to minor foreign object damage (FOD) and grey staining, can be repaired and re-used with signifi cant cost avoidance. The isotropic superfinishing (ISF) process is used to repair the gear by removing surface damage. It has been demonstrated in this project that this surface damage can be removed while maintaining OEM specifications on gear size, geometry and metallurgy. Further, scrap CH-46 mix box spur pinions, repaired by the ISF process, were subjected to gear tooth strength and durability testing, and their performance compared with or exceeded that of new spur pinions procured from an approved Navy vendor. This clearly demonstrates the feasibility of the repair and re-use of precision transmission gears.

702 How Are You Dealing with the Bias Error in Your Helical Gears (May 2009)

This paper initially defines bias error—the “twisted tooth phenomenon.” Using illustrations, we explain that bias error is a by-product of applying conventional, radial crowning methods to produced crowned leads on helical gears. The methods considered are gears that are finished, shaped, shaved, form and generated ground. The paper explains why bias error occurs in these methods and offers techniques used to limit/eliminate bias error. Sometimes, there may be a possibility to apply two methods to eliminate bias error. In those cases, the pros/cons of these methods will be reviewed.

703 Full Speed Ahead (May 2012)

Indexable carbide insert (ICI) cutting tools continue to play a pivotal role in gear manufacturing. By offering higher cutting speeds, reduced cycle times, enhanced coatings, custom configurations and a diverse range of sizes and capabilities, ICI tools have proven invaluable for finishing and pre-grind applications. They continue to expand their unique capabilities and worth in the cutting tool market.

704 High-Tech Risks and Rewards (June 2009)

Aerospace/Defense contracts offer unique challenges for gear manufacturers.

705 The Effect of Superfinishing on Gear Micropitting (March/April 2009)

Results from the Technical University of Munich were presented in a previous technical article (see Ref. 4). This paper presents the results of Ruhr University Bochum. Both research groups concluded that superfinishing is one of the most powerful technologies for significantly increasing the load-carrying capacity of gear flanks.

706 Induction Hardening of Gears and Critical Components - Part II (November/December 2008)

Part I, which was published in the September/October 2008 issue, covered gear materials, desired microstructure, coil design and tooth-by-tooth induction hardening. Part II covers spin hardening and various heating concepts used with it.

707 Influence of Coatings and Surface Improvements on the Lifetime of Gears (July/August 2004)

Surface coatings or finishing processes are the future technologies for improving the load carrying capacity of case hardened gears. With the help of basic tests, the influence of different coatings and finishing processes on efficiency and resistance to wear, scuffing, micropitting, and macropitting is examined.

708 High Speed Steel: Different Grades for Different Requirements (September/October 2004)

Hobs, broaches, shaper cutters, shaver cutters, milling cutters, and bevel cutters used in the manufacture of gears are commonly made of high speed steel. These specialized gear cutting tools often require properties, such as toughness or manufacturability, that are difficult to achieve with carbide, despite the developments in carbide cutting tools for end mills, milling cutters, and tool inserts.

709 Single-Flank Testing of Gears (May/June 2004)

This article was originally published 20 years ago, in Gear Technology’s first issue. It describes a method of evaluating the smoothness, or lack of smoothness, of gear motion. This lack of smoothness of motion, known as “transmission error,” is responsible for excitation of gear noise and problems of gear accuracy and sometimes has a relationship to gear failure.

710 Revolutions (May/June 2004)

"Frenco--Inspecting All Flanks in Minutes."

711 Gear Failure Analysis Involving Grinding Burn (January/February 2009)

When gears are case-hardened, it is known that some growth and redistribution of stresses that result in geometric distortion will occur. Aerospace gears require post case-hardening grinding of the gear teeth to achieve necessary accuracy. Tempering of the case-hardened surface, commonly known as grinding burn, occurs in the manufacturing process when control of the heat generation at the surface is lost.

712 Gear Heat Treatment: The Influence of Materials and Geometry (March/April 2004)

Gear designs are evolving at an ever accelerating rate, and gear manufacturers need to better understand how the choice of materials and heat treating methods can optimize mechanical properties, balance overall cost and extend service life.

713 Evaluation of Bending Strength of Carburized Gears (May/June 2004)

The aim of our research is to clearly show the influence of defects on the bending fatigue strength of gear teeth. Carburized gears have many types of defects, such as non-martensitic layers, inclusions, tool marks, etc. It is well known that high strength gear teeth break from defects in their materials, so it’s important to know which defect limits the strength of a gear.

714 Gear Tooth Scoring Design Considerations for Spur and Helical Gearing (May/June 1985)

High speed gearing, operating with low viscosity lubricants, is prone to a failure mode called scoring. In contrast to the classic failure modes, pitting and breakage, which generally take time to develop, scoring occurs early in the operation of a gear set and can be the limiting factor in the gear's power capability.

715 Cutting Gears on a Machining Center (November/December 2009)

Depo provides all-in-one machining capabilities for the gear industry.

716 Practical Magic - Metrology Products Keep Pace with Machine Technology (July 2009)

Gear metrology is a revolving door of software packages and system upgrades. It has to be in order to keep up with the productivity and development processes of the machines on the manufacturing floor. Temperature compensation, faster inspection times and improved software packages are just a few of the advancements currently in play as companies prepare for new opportunities in areas like alternative energy, automotive and aerospace/defense.

717 Grinding and Abrasives (May/June 2004)

Flexibility and productivity are the keywords in today’s grinding operations. Machines are becoming more flexible as manufacturers look for ways to produce more parts at a lower cost. What used to take two machines or more now takes just one.

718 High Accurate Hobbing with Specially Designed Finishing Hobs (November/December 2003)

Load-carrying capacity of gears, especially the surface durability, is influenced by their tooth surface roughness in addition to their tooth profiles and tooth traces.

719 Hobbing Precise, Uniform End Chamfers (March/April 2004)

The seemingly simple process of placing a uniform chamfer on the face ends of spur and helical gears, at least for the aerospace industry, has never been a satisfactory or cost effective process.

720 Tooth Forms for Hobs (March/April 1985)

The gear hobbing process is a generating type of production operation. For this reason, the form of the hob tooth is always different from the form of the tooth that it produces.

721 Gear Corrosion During the Manufacturing Process (September/October 2009)

No matter how well gears are designed and manufactured, gear corrosion can occur that may easily result in catastrophic failure. Since corrosion is a sporadic and rare event and often difficult to observe in the root fillet region or in finely pitched gears with normal visual inspection, it may easily go undetected. This paper presents the results of an incident that occurred in a gear manufacturing facility several years ago that resulted in pitting corrosion and intergranular attack (IGA).

722 Hard Gear Processing with Skiving Hobs (March/April 1985)

As we approach the problem of hard gear processing, it is well to take a look at the reason for discussing it at this time. In our present economic atmosphere throughout the world, more and more emphasis is being placed upon efficiency which is dictated by higher energy costs.

723 American Manufacturing - Can It Be Saved (November/December 2009)

If anyone should ever need convincing that the state of American manufacturing is in ongoing decline, consider this: the state of Michigan has the highest concentration of engineers in the country, yet also has the highest unemployment rate. But there are ripples of hope out there as grassroots and otherwise organized groups are fighting the good fight in an attempt to reverse that trend.

724 Involute Spline Size Inspection (March/April 1985)

This article describes a new technique for the size determination of external Involute splines by using a span measuring method. It provides application performance information demonstrating how this method and its measurements correlate with the traditional spline ring gage sizing method.

725 In-Situ Measurement of Stresses in Carburized Gears via Neutron Diffraction (May 2009)

This paper presents the results of research directed at measuring the total stress in a pair of statically loaded and carburized spur gears. Measurements were made to examine the change in total stress as a function of externally applied load and depth below the surface.

726 Load Carrying Capacity of Screw Helical Gears with Steel Pinions and Plastic Wheels (July/August 2004)

There is an increasing significance of screw helical and worm gears that combine use of steel and plastics. This is shown by diverse and continuously rising use in the automotive and household appliance industries. The increasing requirements for such gears can be explained by the advantageous qualities of such a material combination in comparison with that of the traditional steel/bronze pairing.

727 Gear Grinding Techniques Parallel Axes Gears (March/April 1985)

The fundamental purpose of gear grinding is to consistently and economically produce "hard" or "soft" gear tooth elements within the accuracy required by the gear functions. These gear elements include tooth profile, tooth spacing, lead or parallelism, axial profile, pitch line runout, surface finish, root fillet profile, and other gear geometry which contribute to the performance of a gear train.

728 ASM Heat Treating Show (October 2011)

Map and listings to the ASM Heat Treating Society Conference and Exposition, which is co-located with this year's Gear Expo.

729 Low-Distortion Heat Treatment of Transmission Components (October 2011)

This paper presents how low pressure carburizing and high pressure gas quenching processes are successfully applied on internal ring gears for a six-speed automatic transmission. The specific challenge in the heat treat process was to reduce distortion in such a way that subsequent machining operations are entirely eliminated.

730 Improved Ion Bond Recoating for the Gear Manufacturing Industry (January/February 1997)

This article summarizes the development of an improved titanium nitride (TiN) recoating process, which has, when compared to conventional recoat methods, demonstrated tool life increases of up to three times in performance testing of hobs and shaper cutters. This new coating process, called Super TiN, surpasses the performance of standard TiN recoating for machining gear components. Super TiN incorporates stripping, surface preparation, smooth coating techniques and polishing before and after recoating. The combination of these improvements to the recoating process is the key to its performance.

731 Dual Frequency Induction Gear Hardening (March/April 1993)

In the typical gear production facility, machining of gear teeth is followed by hear treatment to harden them. The hardening process often distorts the gear teeth, resulting in reduced and generally variable quality. Heat treating gears can involve many different types of operations, which all have the common purpose of producing a microstructure with certain optimum properties. Dual frequency induction hardening grew from the need to reduce cost while improving the accuracy (minimizing the distortion) of two selective hardening processes: single tooth induction and selective carburizing.

732 Investigation of the Strength of Gear Teeth (November/December 1992)

To mechanical engineers, the strength of gear teeth is a question of constant recurrence, and although the problem to be solved is quite elementary in character, probably no other question could be raised upon which such a diversity of opinion exists, and in support of which such an array of rules and authorities might be quoted. In 1879, Mr. John H. Cooper, the author of a well-known work on "Belting," made an examination of the subject and found there were then in existence about forty-eight well-established rules for horsepower and working strength, sanctioned by some twenty-four authorities, and differing from each other in extreme causes of 500%. Since then, a number of new rules have been added, but as no rules have been given which take account of the actual tooth forms in common use, and as no attempt has been made to include in any formula the working stress on the material so that the engineer may see at once upon what assumption a given result is based, I trust I may be pardoned for suggesting that a further investigation is necessary or desirable.

733 1992 Marks Important Gear Design Milestone: Lewis Bending Strenth Equations Now 100 Years old (November/December 1992)

Columbus' first voyage to the Americas is not the only anniversary worthy of celebration this year. In 1892, on October 15, Wilfred Lewis gave an address to the Engineer's Club of Philadelphia, whose significance, while not as great as that of Columbus' voyage, had important results for the gearing community. In this address, Lewis first publicly outlined his formula for computing bending stress in gear teeth, a formula still in use today.

734 Classification of Types of Gear Tooth Wear - Part II (January/February 1993)

The first part of this article included abrasive wear with two bodies, streaks and scoring, polishing, and hot and cold scuffing. This part will deal with three-body wear, scratches or grooves, and interference wear. Normal, moderate, and excessive wear will be defined, and a descriptive chart will be presented.

735 New Cutting Tool Developments in Gear Shaping Technology (January/February 1993)

The advent of CNC technology as applied to gear shaping machines has, in the last 10 years, led to an astonishing improvement in both productivity and quality. As is usual when developments such as this take place, the technology of the machine tool suddenly jumps ahead of that of the cutting tool, and the machine is then capable of producing faster than the cutting tool can withstand.

736 High Technology Hobs (January/February 1993)

Today's high technology hobs are visible different from their predecessors. Gear hobs have taken on a different appearance and function with present day technology and tool and material development. This article shows the newer products being offered today and the reasons for investigating their potential for use in today's modern gear hobbers, where cost reduction and higher productivity are wanted.

737 Hiring & Firing the Older Employee (January/February 1993)

Given the current economic and legal climate, matters of hiring and firing are cause for considerable concern among managers. In addition to all the other factors to be considered, employers must be wary of exactly how these procedures should be carried out, so that the company is not left open to lawsuits based on charges of discrimination of one kind or another. The reasons given for a particular employment decision may be as crucial to determining liability as the decision itself.

738 Environmentally Safe Fluids for Industrial Cutting, Lubrication, & Cleaning (January/February 1993)

Not long ago, many manufacturing managers thought sensitivity to environmental protection standards meant additional expenses, decreased productivity, and a plethora of headaches and hassles.

739 Getting Started in Exporting (March/April 1993)

Exporting. It's one of the hot strategies for helping boost businesses of all kinds, gear manufacturing among them. With domestic markets tight and new markets opening up overseas, exporting seems like a reasonable tactic. But while the pressure is on to sell overseas, there is equal, justifiable concern about whether the move is a good one. Horror stories abound about foreign restrictions, bureaucratic snafus, carloads of paperwork, and the complications and nuances of doing business in other languages and with other cultures.

740 Frozen Gears (March/April 1993)

Durability is the most important criterion used to define the quality of a gear. The freezing of metals has been acknowledged for almost thirty years as an effective method for increasing durability, or "wear life," and decreasing residual stress in tool steels. The recent field of deep cryogenics (below -300 degrees F) has brought us high temperature superconductors, the superconducting super collider, cryo-biology, and magnotehydrodynamic drive systems. It has also brought many additional durability benefits to metals.

741 Controlling Carburizing for Top Quality Gears (March/April 1993)

A carburized alloy steel gear has the greatest load-carrying capacity, but only if it is heat treated properly. For high quality carburizing, the case depth, case microstructure, and case hardness must be controlled carefully.

742 Little Things Mean A Lot (March/April 1993)

"God is in the details," says the philosopher. What he meant was that on the scale of the universe, it's not just the galaxies, the planets, the mountain ranges, or the major rivers that are important. So are the subatomic particles and the genes. It's the little things that make all the difference.

743 Delivering The Goods (May/June 1993)

One of the key questions to be answered when exporting is how you are going to get your product to your customer. All the time, effort, and money you've spent to make a sale in the first place can be wasted if the shipment is late, damaged, or lost, or if delivery becomes an expensive bureaucratic nightmare for either you or the buyer.

744 CNC Technology and the System-Independent Manufacture of Spiral Bevel Gears (September/October 1992)

CNC technology offers new opportunities for the manufacture of bevel gears. While traditionally the purchase of a specific machine at the same time determined a particular production system, CNC technology permits the processing of bevel gears using a wide variety of methods. The ideological dispute between "tapered tooth or parallel depth tooth" and "single indexing or continuous indexing" no longer leads to an irreversible fundamental decision. The systems have instead become penetrable, and with existing CNC machines, it is possible to select this or that system according to factual considerations at a later date.

745 Using Hobs for Skiving; A Pre-Finish and Finishing Solution (May/June 1993)

Our company manufactures a range of hardened and ground gears. We are looking into using skiving as part of our finishing process on gears in the 4-12 module range made form 17 CrNiMO6 material and hardened to between 58 and 62 Rc. Can you tell us more about this process?

746 Computerized Recycling of Used Gear Shaver Cutters (May/June 1993)

Most gear cutting shops have shelves full of expensive tooling used in the past for cutting gears which are no longer in production. It is anticipated that these cutters will be used again in the future. While this may take place if the cutters are "standard," and the gears to be cut are "standard," most of the design work done today involves high pressure angle gears for strength, or designs for high contact ratio to reduce noise. The re-use of a cutter under these conditions requires a tedious mathematical analysis, which is no problem if a computer with the right software is available. This article describes a computerized graphical display which provides a quick analysis of the potential for the re-use of shaving cutters stored in a computer file.

747 The Limits of the Computer Revoltion (May/June 1993)

In this issue of Gear Technology, we are focusing on using computers to their greatest advantage in gear design and manufacturing. In a sense, that's old news. It's a cliche to suggest that computers make our work life easier and more productive. No company that wishes to remain competitive in today's global manufacturing environment can afford to be without computers in all their manifestations. We need them in the office; we need them next to our desks in place of drafting boards; we need them on the shop floor.

748 Money Business: Exporting - Part III (July/August 1993)

The object of any business transaction, be it foreign or domestic, is making a profit. That's why you go through all the effort of making and selling your product in the first place. Getting paid in a timely manner is crucial to making profit, but when your customer is in another country, this "timely and convenient" payment can become complicated; hence, your need for a banker with expertise in international markets.

749 Gear Tip Chamfer and Gear Noise; Surface Measurement of Spiral Bevel Gear Teeth (July/August 1993)

Could the tip chamfer that manufacturing people usually use on the tips of gear teeth be the cause of vibration in the gear set? The set in question is spur, of 2.25 DP, with 20 degrees pressure angle. The pinion has 14 teeth and the mating gear, 63 teeth. The pinion turns at 535 rpm maximum. Could a chamfer a little over 1/64" cause a vibration problem?

750 CNC Bevel Gear Generators and Flared Cup Gear Grinding (July/August 1993)

New freedom of motion available with CNC generators make possible improving tooth contact on bevel and hypoid gears. Mechanical machines by their nature are inflexible and require a special mechanism for every desired motion. These mechanisms are generally exotic and expensive. As a result, it was not until the introduction of CNC generators that engineers started exploring motion possibilities and their effect on tooth contact.

751 Hob Basics Part I (September/October 1993)

The Hobbing Process The hobbing process involves a hob which is threaded with a lead and is rotated in conjunction with the gear blank at a ratio dependent upon the number of teeth to be cut. A single thread hob cutting a 40-tooth gear will make 40 revolutions for each revolution of the gear. The cutting action in hobbing is continuous, and the teeth are formed in one passage of the hob through the blank. See Fig. 1 for a drawing of a typical hob with some common nomenclature.

752 Rules of Engagement Exporting - Part IV (September/October 1993)

Putting one's best foot forward is important for successful business communication. And successful business people know the "rule" of the game, what it say and do in business situations, to make the best impression. However, these rules change from country to country, and what is appropriate behavior here may appear rude to someone from Latin America, Europe or Asia To help you become more familiar with some of the different rules of engagement in other countries, Gear Technology spoke with three businessmen who have had extensive contact in various part of the world.

753 Hob Basics Part II (November/December 1993)

This is Part II of a two-part series on the basics of gear hobbing. Part I discussed selection of the correct type of hobbing operation, the design features of hobs and hob accuracy. This part will cover sharpening errors and finish hob design considerations.

754 CBN Gear Grinding - A Way to Higher Load Capacity (November/December 1993)

Because of the better thermal conductivity of CBN abrasives compared to that of conventional aluminum oxide wheels, CBN grinding process, which induces residual compressive stresses into the component, and possibly improves the subsequent stress behavior. This thesis is the subject of much discussion. In particular, recent Japanese publications claim great advantages for the process with regard to an increased component load capacity, but do not provide further details regarding the technology, test procedures or components investigated. This situation needs clarification, and for the this reason the effect of the CBN grinding material on the wear behavior and tooth face load capacity of continuously generated ground gears was further investigated.

755 Generation of Helical Gears with New Surface Topology by Application of CNC Machines (January/February 1994)

Analysis of helical involute gears by tooth contact analysis shows that such gears are very sensitive to angular misalignment leading to edge contact and the potential for high vibration. A new topology of tooth surfaces of helical gears that enables a favorable bearing contact and a reduced level of vibration is described. Methods for grinding helical gears with the new topology are proposed. A TCA program simulating the meshing and contact of helical gears with the new topology has been developed. Numerical examples that illustrate the proposed ideas are discussed.

756 The Gear Hobbing Process (January/February 1994)

Gear hobbing is a generating process. The term generating refers to the fact that the gear tooth form cut is not the conjugate form of the cutting tool, the hob. During hobbing both the hob and the workpiece rotate in a continuous rotational relationship. During this rotation, the hob is typically fed axially with all the teeth being gradually formed as the tool traverses the work face (see Fig. 1a).

757 Classification of Types of Gear Tooth Wear - Part I (November/December 1992)

The phenomena of deterioration of surfaces are generally very complex and depend on numerous conditions which include the operating conditions, the type of load applied, the relative speeds of surfaces in contact, the temperature, lubrication, surfaces hardness and roughness, and the compatibility and nature of materials.

758 The Bottom Line on Trade Shows (September/October 1992)

The whole point of a trade show is to get leads that will turn into sales. No matter how attractive your booth was, no matter how smoothly the setup and the show ran, no matter how many visitors you had at your booth, if your presence at a show didn't net you any sales, then your considerable investment of time, money, and effort has been wasted.

759 Innovative CNC Gear Shaping (January/February 1994)

The Shaping Process - A Quick Review of the Working Principle. In the shaping process, cutter and workpiece represent a drive with parallel axes rotating in mesh (generating motion) according to the number of teeth in both cutter and workpiece (Fig. 1), while the cutter reciprocates for the metal removal action (cutting motion).

760 Optimum Shot Peening Specification - I (November/December 1991)

Shot peening is widely recognized as a prove, cost-effective process to enhance the fatigue characteristics of metal parts and eliminate the problems of stress corrosion cracking. Additional benefits accrue in the areas of forming and texturizing. Though shot peening is widely used today, the means of specifying process parameters and controlling documents for process control are not widely understood. Questions regarding shot size, intensity, and blueprint specification to assure a high quality and repeatable shot peening process are continually asked by many design and materials engineers. This article should answer many of the questions frequently asked by engineering professionals and to further assist companies interested in establishing a general shot peening specification.

761 Hard Finishing By Conventional Generating and Form Grinding (March/April 1991)

The quality of a gear and its performance is determined by the following five parameters, which should be specified for each gear: Pitch diameter, involute form, lead accuracy, spacing accuracy, and true axis of rotation. The first four parameters can be measured or charted and have to be within tolerance with respect to the fifth. Pitch diameter, involute, lead, and spacing of a gear can have master gear quality when measured or charted on a testing machine, but the gear might perform badly if the true axis of rotation after installation is no longer the same one used when testing the gear.

762 Bevel Gear Manufacturing Troubleshooting (March/April 1991)

The quality of gearing is a function of many factors ranging from design, manufacturing processes, machine capability, gear steel material, the machine operator, and the quality control methods employed. This article discusses many of the bevel gear manufacturing problems encountered by gear manufacturers and some of the troubleshooting techniques used.

763 Misalignment No Beauty in Gearsets (May/June 1991)

When we have problems with gearset failure, a common diagnosis is misalignment. What exactly is that and how do we prevent it? The second most common "killer" of good gear sets is misalignment (dirt, or abrasive wear, is first). Gear teeth simply won't carry the load if they don't touch, and the portion that does touch has to carry an overload to make up for the missing contact area.

764 Carbide Hobs (May/June 1991)

The following article is a collection of data intended to give the reader a general overview of information related to a relatively new subject within the gear cutting industry. Although carbide hobbing itself is not necessarily new, some of the methods and types of application are. While the subject content of this article may be quite broad, it should not be considered all-inclusive. The actual results obtained and the speeds, feeds, and tool life used in carbide hobbing applications can vary significantly.

765 Surface Pitting Fatigue Life of Noninvolute Low-Contact-Ratio Gears (May/June 1991)

Spur gear endurance tests were conducted to investigate the surface pitting fatigue life of noninvolute gears with low numbers of teeth and low contact ratios for the use in advanced application. The results were compared with those for a standard involute design with a low number of teeth. The gear pitch diameter was 8.89 cm (3.50 in.) with 12 teeth on both gear designs. Test conditions were an oil inlet temperature of 320 K (116 degrees F), a maximum Hertz stress of 1.49 GPa (216 ksi), and a speed of 10,000 rpm. The following results were obtained: The noninvolute gear had a surface pitting fatigue life approximately 1.6 times that of the standard involute gear of a similar design. The surface pitting fatigue life of the 3.43-pitch AISI 8620 noninvolute gear was approximately equal to the surface pitting fatigue life of an 8-pitch, 28-tooth AISI 9310 gear at the same load, but at a considerably higher maximum Hertz stress.

766 Pacific Rim Gives Stiff Competition To U.S, Gear Producers (July/August 1991)

This past fall, I had the opportunity to travel to Japan, Korea, Taiwan, and Singapore to witness first-hand the status of the power transmission and machine tool industries in these areas. Points of interest included equipment, material handling, computerization, wage and tax structures, inventory controls, and workforce attitude.

767 Pineapples, Corncobs & Other Hobbing Matters (July/August 1991)

Two questions on hobbing cover the various types of hobs and their unusual names, as well as the importance of hob swivel angle.

768 Gear Fundamentals Reverse Engineering (July/August 1991)

Whether gear engineers have to replace an old gear which is worn out, find out what a gear's geometry is after heat treatment distortion, or just find out parameters of gears made by a competitor, sometimes they are challenged with a need to determine the geometry of unknown gears. Depending on the degree of accuracy required, a variety of techniques are available for determining the accuracy of an unknown gear. If a high degree of precision is important, a gear inspection device has to be used to verify the results. Frequently, several trial-and-error attempts are made before the results reach the degree of precision required.

769 Full-Load Testing of Large Gearboxes Using Closed-Loop Power Circulation (September/October 1991)

This method of testing large gearboxes or, indeed, any power transmission element, had numerous advantages and offers the possibility of large savings in time, energy, and plant, if the overall situation is conducive to its use. This usually requires that several such units need to be tested, and that they can be conveniently connected to each to each other in such a way as to form a closed-loop drive train. No power sink is required, and the drive input system has only to make up power losses. The level of circulating power is controlled by the torque, which is applied statically during rotation, and the drive speed. Principles, advantage, and limitations are described, together with recent experiences in the only known large-scale usage of this technique in Australia.

770 SPC Acceptance of Hobbing & Shaping Machines (September/October 1991)

Today, as part of filling a typical gear hobbing or shaping machine order, engineers are required to perform an SPC acceptance test. This SPC test, while it is contractually necessary for machine acceptance, is not a machine acceptance test. It is a process capability test. It is an acceptance of the machine, cutting tool, workholding fixture, and workpiece as integrated on the cutting machine, using a gear measuring machine, with its work arbor and evaluation software, to measure the acceptance elements of the workpiece.

771 Single Flank Measuring; Estimating Horsepower Capacity (September/October 1991)

Question: What is functional measurement and what is the best method for getting truthful answers?

772 Viewpoint (November/December 1991)

Dear Editor: In Mr. Yefim Kotlyar's article "Reverse Engineering" in the July/August issue, I found an error in the formula used to calculate the ACL = Actual lead from the ASL = Assumed lead.

773 Cutting Low-Pitch-Angle Bevel Gears, Worm Gears and The Oil Entry Gap (July/August 1992)

Question: Do machines exist that are capable of cutting bevel gear teeth on a gear of the following specifications: 14 teeth, 1" circular pitch, 14.5 degrees pressure angle, 4 degrees pitch cone angle, 27.5" cone distance, and an 2.5" face width?

774 A Rational Procedure for Designing Minimum-Weight Gears (November/December 1991)

A simple, closed-form procedure is presented for designing minimum-weight spur and helical gearsets. The procedure includes methods for optimizing addendum modification for maximum pitting and wear resistance, bending strength, or scuffing resistance.

775 To Market, To Market (November/December 1991)

A few months ago at the AGMA management seminar, I was surprised by the feverish note taking that went on at a presentation on marketing. The sight reminded me that while many of us in the gear industry are good engineers, designers, and mangers, we are often not as familiar - or comfortable - with less concrete concepts, such as marketing.

776 Gear Inspection Chart Evaluation; Specifying Unusual Worm Gear Sets (November/December 1991)

Question: When evaluating charts from a gear inspection machine, it is sometimes found that the full length of the profile traces vary, and that sometimes they are less than the length of active profile (above start of active profile-SAP) by up to 20%. This condition could be caused by a concentricity error between tooth grinding and shaping, or by unequal stock removal when grinding. (See Fig. 1.) Is it possible that some of the variation is coming from the inspection machine? How can variation from the inspection machine be reduced?

777 Optimum Shot Peening Specification - II (January/February 1992)

Following is the second part of an article begun in our last issue. The first part covered basic shot peening theory, shot peening controls, and considerations that should go into developing a shot peening specification. Part II covers optional peening methods and the relationship of shot peening specifications to the drawings.

778 The Right and Wrong of Modern Hob Sharpening (January/February 1992)

Precision gears play a vital role in today's economy. Through their application, automobile transmissions are more compact and efficient, ships sail faster, and diesel locomotives haul more freight. Today great emphasis is being placed upon the reduction of noise in all gear applications and, to be quiet, gears must be accurate.

779 Gear Hardness Technology (March/April 1992)

In a very general sense, increasing the hardness of a steel gear increases the strength of the gear. However, for each process there is a limit to its effectiveness. This article contains background information on each of the processes covered. In each section what is desired and what is achievable is discussed. Typical processes are presented along with comments on variables which affect the result. By reviewing the capabilities and processes, it is possible to determine the limits to each process.

780 Our Experts Discuss Hobbing Ridges, Crooked Gear Teeth, and Crown Shaving (March/April 1992)

Question: When cutting worm gears with multiple lead stock hobs we find the surface is "ridged". What can be done to eliminate this appearance or is to unavoidable?

781 Gear Blanking (May/June 1992)

The term "blanking" refers to the initial metal cutting operations in the process planning sequence which produce the contour of a part starting from rough material. The scope of blanking is: To remove the excess material To machine the part to print specifications, except for those surfaces with subsequent finishing operations. To leave adequate machining stock for finishing operations. To prepare good quality surfaces for location and clamping of the part throughout the process.

782 Investing in Ourselves is the Key to Revitalizing American Manufacturing (July/August 1992)

Popular wisdom has it that manufacturing in the United States is no longer a viable entity. We are told that quality is poor, skilled labor is difficult to obtain, if not impossible, demand is low, and the government is helping to discourage business. So what should we do, give up?

783 Operation Trade Show (July/August 1992)

Organizing a successful trade show exhibit is not unlike running Operation Desert Storm. The logistics can be a nightmare; the expense, horrendous; the details, mind-boggling. About the only thing you won't have to cope with is having someone fire SCUD missiles at you.

784 Comparing Surface Failure Modes in Bearings and Gears: Appearances vs. Mechanisms (July/August 1992)

In the 1960's and early 1970's, considerable work was done to identify the various modes of damage that ended the lives of rolling element bearings. A simple summary of all the damage modes that could lead to failure is given in Table 1. In bearing applications that have insufficient or improper lubricant, or have contaminants (water, solid particles) or poor sealing, failure, such as excessive wear or vibration or corrosion, may occur, rather than contact fatigue. Usually other components in the overall system besides bearings also suffer. Over the years, builders of transmissions, axles, and gear boxes that comprise such systems have understood the need to improve the operating environment within such units, so that some system life improvements have taken place.

785 Grinding of Spur and Helical Gears (July/August 1992)

Grinding is a technique of finish-machining, utilizing an abrasive wheel. The rotating abrasive wheel, which id generally of special shape or form, when made to bear against a cylindrical shaped workpiece, under a set of specific geometrical relationships, will produce a precision spur or helical gear. In most instances the workpiece will already have gear teeth cut on it by a primary process, such as hobbing or shaping. There are essentially two techniques for grinding gears: form and generation. The basic principles of these techniques, with their advantages and disadvantages, are presented in this section.

786 Cutting Worm Gears with Standard Gear Hobs (January/February 1994)

We make a lot of single-start worm and worm gear sets, and it always seems as though we're buying another special hob. We also do a lot of spur gear cutting, and the spur gear hobs and the worm gear hobs look alike, so we wonder why we cannot use the standard hobs for cutting worm gears too. Can we do this?

787 The Fundamentals of Gear Press Quenching (March/April 1994)

Most steel gear applications require appreciable loads to be applied that will result in high bending and compressive stresses. For the material (steel) to meet these performance criteria, the gear must be heat treated. Associated with this thermal processing is distortion. To control the distortion and achieve repeatable dimensional tolerances, the gear will be constrained during the quenching cycle of the heat treatment process. This type of fixture quenching is the function of gear quench pressing equipment.

788 Are You Ready to Choose An Advertising Agency (March/April 1991)

Countless research studies confirm this fact: Companies that advertise aggressively during a recession will flourish after the economic tide turns. Regardless of company size, effective advertising generally requires the services of an agency, and under current economic conditions, you may need one now more than ever. The question is, how do you go about getting the right one for your company.

789 Minimizing Gear Distortion During Heat Treating (March/April 1996)

Graded hardening technology has proven over the years to yield very good results when used in the heat treating of carburized gears. It is especially advantageous for smaller companies, subject to higher competitive pressures. Unfortunately, despite the fact that graded hardening is a very well-known method, its use has been limited. We strongly recommend this technology to all of those who need to produce gears with high metallurgical quality.

790 New Concepts in CNC Gear Shaping (July/August 1995)

In today's economy, when purchasing a new state-of-the-art gear shaper means a significant capital investment, common sense alone dictates that you develop strategies to get the most for your money. One of the best ways to do this is to take advantage of the sophistication of the machine to make it more than just a single-purpose tool.

791 A Basic Guide to Deburring and Chamfering Gears (July/August 1995)

In today's industrial marketplace, deburring and chamfering are no longer just a matter of cosmetics. The faster speeds at which transmissions run today demand that gear teeth mesh as smoothly and accurately as possible to prevent premature failure. The demand for quieter gears also requires tighter tolerances. New heat treating practices and other secondary gear operations have placed their own set of demands on manufacturers. Companies that can deburr or chamfer to these newer, more stringent specifications - and still keep costs in line - find themselves with a leg up on their competition.

792 Dry Gear Hobbing (July/August 1995)

Question: We are contemplating purchasing a hobbing machine with dry hobbing capabilities. What do we need to know about the special system requirements for this technology?

793 Gear Grinding 1995 (July/August 1995)

Gear grinding is one of the most expensive and least understood aspects of gear manufacturing. But with pressures for reduced noise, higher quality and greater efficiency, gear grinding appears to be on the rise.

794 Gear Inspection For The Long Haul (September/October 1995)

Question: We just received permission to purchase our first CNC gear inspection system. With capital approvals so hard to come by, especially for inspection equipment, I want to be sure to purchase a system I can count of for years to come. My past experience with purchasing CNC equipment has shown me that serviceability of the computer and the CNC controller portion of the system can be a problem in just a few years because of the obsolescence factor. What information do I need to look for when selecting a supplier to reduce the risk of obsolescence, as well as to reduce the long-term servicing costs in the computer and controls portion of the system?

795 A Huge Success (September/October 1995)

Sivyer Steel Corporation, Bettendorf, IA, an ISO-9002-certified casting specialist, is familiar with tackling tough jobs. The company has built an international reputation as a supplier of high-integrity castings, especially those which require engineering and/or full machining. Its not unusual for Sivyer's customers, especially those in the mining, recycling, power generation, valve and nuclear fields, to ask the foundry to produce a one-of-a-kind casting - often something revolutionary - but AnClyde Engineered Products' request was a special challenge, even for Sivyer.

796 Peter Kozma of Liebherr-America, Inc. (September/October 1995)

Peter Kozma, executive vice president of Liebherr-America, Inc., talks with us about Liebherr and its partners in the Sigma Pool.

797 Determining Spline Misalignment Capabilities (November/December 1995)

Introducing backlash into spline couplings has been common practice in order to provide for component eccentric and angular misalignment. The method presented here is believed to be exact for splines with even numbers of teeth and approximate for those with odd numbers of teeth. This method is based on the reduction of the maximum effective tooth thickness to achieve the necessary clearance. Other methods, such as tooth crowning, are also effective.

798 The Next Step in Bevel Gear Metrology (January/February 1996)

In recent years, gear inspection requirements have changed considerably, but inspection methods have barely kept pace. The gap is especially noticeable in bevel gears, whose geometry has always made testing them a complicated, expensive and time-consuming process. Present roll test methods for determining flank form and quality of gear sets are hardly applicable to bevel gears at all, and the time, expense and sophistication required for coordinate measurement has limited its use to gear development, with only sampling occurring during production.

799 Material Selection and Heat Treatment Part II Metalurgical Characteristics (September/October 1985)

The approximate tensile strength of any steel is measured by its hardness, Table 1. Since hardness is determined by both chemical composition and heat treatment, these are the two important metallurgical considerations in selecting gear steels.

800 The Next Generation of Gear Specialists (January/February 1996)

AGMA has an excellent Training School for Gear Manufacturing. It's a great product providing a great service to the gear industry. Thus far we've educated 117 employees from 71 companies; students range from new hires with no experience to company presidents. Essentially every class since December, 1992, has been sold out.

801 Wear Protection for Gears (March/April 1996)

Several trends in mechanical engineering are leading to greater surface stress on components and thus to unacceptable wear. These trends include greater stresses due to increased power densities; the need to maintain high precision of components throughout their service life; and the environmental imperative to reduce use of lubricants and additives.

802 Hotter, Faster, Harder Cutting (July/August 1995)

What Is Whisker-Reinforced Ceramic? Whisker-reinforced ceramic as applied to cutting tool inserts comprises a matrix of aluminum oxide into which approximately 50% by volume of high-purity silicon carbide "whiskers" are randomly dispersed. The "whiskers" are, in fact, single crystals having dimensions of approximately 0.6 microns in diameter x 10-80 microns in length. These "whiskers" have a tensile strength on the order of 1,000,000 psi (690 MPa). The composite material that is the best known and most widely applied using this technology is designated WG-300 and manufactured by the Greenleaf Corporation of Saegertown, PA.

803 Heat Treating Challenges for the Future (March/April 1996)

The heat treating of gears presents a difficult challenge to both the heat treater and the gear manufacturer. The number and variety of variables involved in the manufacturing process itself and the subsequent heat treating cycle create a complex matrix of factors which need to be controlled in order to produce a quality product. A heat treater specializing in gears or a gear manufacturer doing his own heat treating must have a clear understanding of these issues in order to deliver a quality product and make a profit at the same time. The situation also presents a number of areas that could benefit greatly from continued research and development.

804 Other People's Footsteps (May/June 1996)

Earlier this year, a relative of mine, Sidney Mandell, tragically passed away. I had the good fortune to serve with Sidney on the Board of Directors and the Executive Committee of the Machinery Dealers National Association (MDNA). Though he started before me, his MDNA career and mine overlapped for about 2 years. As I think back on the many things I learned form him, one of his favorite phrases keeps come to mind: "We walk in the footsteps of those who have gone before us."

805 Cutting Tools Now (May/June 1996)

The cutting tool is basic to gear manufacturing. Whether it's a hob, broach, shaper cutter or EDM wire, not much gets done without it. And the mission of the tool remains the same as always; removing material as quickly, accurately and cost-effectively as possible. Progress in the field tends to be evolutionary, coming gradually over time, but recently, a confluence of emerging technologies and new customer demands has caused significant changes in the machines, the materials and the coatings that make cutting tools.

806 EDM Specialty Gears (May/June 1996)

The capabilities and limitations of manufacturing gears by conventional means are well-known and thoroughly documented. In the search to enhance or otherwise improve the gear-making process, manufacturing methods have extended beyond chip-cutting - hobbing, broaching, shaping, shaving, grinding, etc. and their inherent limitations based on cutting selection and speed, feed rates, chip thickness per tooth, cutting pressure, cutter deflection, chatter, surface finish, material hardness, machine rigidity, tooling, setup and other items.

807 Generating Precision Spur Gears By Wire EDM (May/June 1996)

Over the past decade, the wire electrical discharge machine (EDM) has become an increasingly important tool for machining non-standard shapes. It has even been used to cut gears and gear cavities for plastic molds. While generally accepted as a quick and versatile method for cutting spur gears, the EDM gear has lacked the precision of a mechanically machined or ground gear. We suspected that many of the errors associated with these gears were caused by inexact setup procedures, poor tool path control and improper cutting parameters. We decided to test the potential for the wire EDM to make the most accurate gear possible.

808 Racing Circuits (May/June 1996)

Zero to 125 MPH in five seconds. Maximum speed of 211 MPH. Seven-second pit stops. Formula One racing is a high-adrenalin sport - one which demands peak performance from drivers and machines alike.

809 Design Implications for Shaper Cutters (July/August 1996)

A gear shaper cutter is actually a gear with relieved cutting edges and increased addendum for providing clearance in the root of the gear being cut. The maximum outside diameter of such a cutter is limited to the diameter at which the teeth become pointed. The minimum diameter occurs when the outside diameter of the cutter and the base circle are the same. Those theoretical extremes, coupled with the side clearance, which is normally 2 degrees for coarse pitch cutters an d1.5 degrees for cutters approximately 24-pitch and finer, will determine the theoretical face width of a cutter.

810 Gear Noise As a Result of Nicks, Burrs and Scale - What Can Be Done (July/August 1996)

There are many different causes of gear noise, all of them theoretically preventable. Unfortunately, the prevention methods can be costly, both in equipment and manpower. If the design of the gear and its application are appropriate, in theory all that is necessary is to have a tight control on the process of producing the finished gear. In reality, there are many variables that can cause a process, no matter how well-controlled, to deteriorate, and thus cause errors, some of which will cause a gear to produce unwanted noise when put to use.

811 The Advantages of Ion Nitriding Gears (November/December 1996)

When it comes to setting the standard for gear making, the auto industry often sets the pace. Thus when automakers went to grinding after hardening to assure precision, so did the machine shops that specialize in gearing. But in custom manufacturing of gears in small piece counts, post-heat treat grinding can grind away profits too.

812 Dry Hobbing Saves Automaker Money, Improves Gear Quality (November/December 1996)

It takes confidence to be the first to invest in new manufacturing technology. But the payback can be significant. That has been the experience at the Ford Motor Company's Transmission & Chassis Division plant at Indianapolis, IN, which boasts the world's first production application of dry hobbing.

813 Chamfering and Deburring External Parallel Axis Gears (November/December 1996)

The chamfering and deburring operations on gear teeth have become more important as the automation of gear manufacturing lines in the automotive industry have steadily increased. Quieter gears require more accurate chamfers. This operation also translates into significant coast savings by avoiding costly rework operations. This article discusses the different types of chamfers on gear teeth and outlines manufacturing methods and guidelines to determine chamfer sizes and angles for the product and process engineer.

814 Hard Coatings on Contaminated Surfaces - A Case Study (January/February 1997)

Physical Vapor Deposited (PVD) coatings such as TiN (Titanium nitride) have been a boon for cutting tool manufacturers. They reduce wear and, therefore, extend tool life, which in turn reduces production costs. But PVD coatings are expensive, and when they fail, they cost both time and money, and they causes of the failure are not always readily apparent.

815 The Shape of Things to Come (July/August 1995)

An engineer's responsibility for verifying a new design or product concept as manufacturable early in the development cycle is a tough challenge. What appears to work on a blueprint or in a three-dimensional CAD file on a computer screen many not work on the factory floor; and the downstream impact on the manufacturing process of an undetected design flaw can be enormous. Costs can run into the millions.

816 Gear Grinding Comes of Age (July/August 1995)

In the quest for ever more exacting and compact commercial gears, precision abrasives are playing a key production role - a role that can shorten cycle time, reduce machining costs and meet growing market demand for such requirements as light weights, high loads, high speed and quiet operation. Used in conjunction with high-quality grinding machines, abrasives can deliver a level of accuracy unmatched by other manufacturing techniques, cost-effectively meeting AGMA gear quality levels in the 12 to 15 range. Thanks to advances in grinding and abrasive technology, machining has become one of the most viable means to grind fast, strong and quiet gears.

817 Investigation of Surface Layer and Wear Behavior of Nitrided Gear Drives (March/April 1994)

In this article we will characterize the nitride layers that are generated by different nitriding processes and compare their respective wear characteristics.

818 Gear Hobbing Without Coolant (November/December 1994)

For environmental and economic reasons, the use of coolant in machining processes is increasingly being questioned. Rising coolant prices and disposal costs, as well as strains on workers and the environment, have fueled the debate. The use of coolant has given rise to a highly technical system for handling coolant in the machine (cooling, filtering) and protecting the environment (filter, oil-mist collector). In this area the latest cutting materials - used with or without coolant - have great potential for making the metal-removal process more economical. The natural progression to completely dry machining has decisive advantages for hobbing.

819 The Tech Prep Approach to Worker Training (May/June 1994)

"More than half our young people leave school without the knowledge or foundation required to find and hold a job." according to a 1991 report from the U.S. Dept. of Labor. A huge gap exists between the needs of employers (especially in manufacturing) and the training received by most high school students.

820 Computerized Hob Inspection & Applications of Inspection Results - Part I (May/June 1994)

Can a gear profile generated by the hobbing method be an ideal involute? In strictly theoretical terms - no, but in practicality - yes. A gear profile generated by the hobbing method is an approximation of the involute curve. Let's review a classic example of an approximation.

821 Designing Hardened & Ground Spur Gears to Operate With Minimum Noise (May/June 1994)

When designing hardened and ground spur gears to operate with minimum noise, what are the parameters to be considered? should tip and/or root relief be applied to both wheel and pinion or only to one member? When pinions are enlarged and he wheel reduced, should tip relief be applied? What are the effects on strength, wear and noise? For given ratios with enlarged pinions and reduced wheels, how can the gear set sized be checked or adjusted to ensure that the best combination has been achieved?

822 Getting With The Program (May/June 1994)

Getting and keeping a work force capable of meeting the demands of the 21st century is one of the key challenges most U.S. manufacturers face today. That's not even news anymore. I - and others - have been talking about it in editorials and speeches for ten years now. It's also not news that the job is a tough one and that industry-wide response often has not been particularly effective.

823 Minimizing Backlash in Spur Gears (May/June 1994)

simplified equations for backlash and roll test center distance are derived. Unknown errors in measured tooth thickness are investigate. Master gear design is outlined, and an alternative to the master gear method is described. Defects in the test radius method are enumerated. Procedures for calculating backlash and for preventing significant errors in measurement are presented.

824 Carbide Rehobbing A New Technology That Works! (May/June 1994)

Many people in the gear industry have heard of skiving, a process wherein solid carbide or inserted carbide blade hobs with 15 - 60 degrees of negative rake are used to recut gears to 62 Rc. The topic of this article is the use of neutral (zero) rake solid carbide hobs to remove heat treat distortion, achieving accuracies of AGMA 8 to AGMA 14, DIN 10-5 and improving surface finish on gears from 8 DP - 96 DP (.3 module - .26 m.).

825 Computerized Hob Inspection & Applications of Inspection Results Part II (July/August 1994)

Flute Index Flute index or spacing is defined as the variation from the desired angle between adjacent or nonadjacent tooth faces measured in a plane of rotation. AGMA defines and provides tolerance for adjacent and nonadjacent flute spacing errors. In addition, DIN and ISO standards provide tolerances for individual flute variation (Fig. 1).

826 Making the Most of Your Trade Show Visit: Avoid These 18 Common Mistakes (July/August 1994)

Going to IMTS? Beware. It's easy to make any number of common mistakes that can turn your productive buying trip into an expensive bomb.

827 New Innovations in Hobbing - Part I (September/October 1994)

Prior to the introduction of titanium nitride to the cutting tool industry in the early 1980s, there was very little progress in the general application of hobbing in the gear cutting industry. The productivity gains realized with this new type of coating initiated a very active time of advancement in the gear manufacturing process.

828 Our Experts Discuss Electronic Gearboxes, Plus Backlash and What to Do about it (September/October 1994)

Question: In the January/February issue of your magazine, we came across the term "electronic gearbox." We have seen this term used elsewhere as well. We understand that this EGB eliminates the change gear in the transmission line, but not how exactly this is done. Could you explain in more detail?

829 Quality Gear Inspection - Part I (September/October 1994)

Quality gear inspection means doing the "right" inspections "right." A lot of time and money can be spent doing the wrong types of inspections related to function and doing them incorrectly. As we will discover later, such things as runout can creep into the manufacturing and inspection process and completely ruin any piece of data that is taken. this is one of the most important problems to control for quality inspection.

830 New Innovations in Hobbing - Part II (November/December 1994)

The first part of this article, which ran in the September/October 1994 issue, explained the fundamentals of gear hobbing and some of the latest techniques, including methods of hob performance analysis and new tool configurations, being used to solve specific application problems. In this issue, the author continues his exploration of hobbing by describing the effects of progress on requirements in accuracy, as well as the latest in materials, coating and dry hobbing.

831 INFAC Reports on Recent Hobbing and Heat Treating Experiments (July/August 1995)

Chicago- Results of recent studies on residual stress in gear hobbing, hobbing without lubricants and heat treating were reported by representatives of INFAC (Instrumented Factory for Gears) at an industry briefing in March of this year.

832 Quality Gear Inspection - Part II (November/December 1994)

This section will deal with the use of gear inspection for diagnostic purposes rather than quality determination. The proper evaluation of various characteristics in the data can be useful for the solution of quality problems. It is important to sort out whether the problem is coming from the machine, tooling and/or cutters, blanks, etc. An article by Robert Moderow in the May/June 1985 issue of Gear Technology is very useful for this purpose.

833 Multi-Metal Composite Gear-Shaft Technology (January/February 1995)

A research program, conducted in conjunction with a U.S. Army contract, has resulted in the development of manufacturing technology to produce a multi-metal composite gear/shaft representing a substantial weight savings compared to a solid steel component. Inertia welding is used to join a steel outer ring to a light-weight titanium alloy web and/or shaft through the use of a suitable interlayer material such as aluminum.

834 The Second Edition... (March/April 1995)

Gearing for Munchkins Gene Kasten, president of Repair Parts, Inc., of Rockford, IL, is the proud owner of a miniature Barber-Colman hobber, the only one of its kind in the world. The machine, a replica of the old B-C "A" machine, was built between 1933 and 1941 by W. W. Dickover, who devoted 2, 640 hours of his spare time to the project.

835 Finding Tomorrow's Leaders Today (March/April 1995)

The passage last year of both NAFTA and GATT has gone a long way toward leveling the playing field for American manufacturers and other hoping to compete in the global economy. Add to this news the fact that the domestic economy keeps growing, and it seems as though good times are ahead for the gear industry.

836 Heat Treating Equipment Selection (March/April 1995)

For heat treatment of tool and alloy steels, the end-user has a wide range of basic types of heat treating equipment to choose from. This article reviews them and details the criteria that must be considered in selecting equipment for a specific application. In making this choice, the most important criterion must be the quality of the tool or part after processing.

837 Gear Heat Treating in the 90s: Beyond Black Magic (March/April 1995)

Heat Treating - The evil twin of the gear processing family. Heat treating and post-heat treating corrective processes can run up to 50% or more of the total gear manufacturing cost, so it's easy to see why, in these days when "lean and mean" production is the rage, and every part of the manufacturing process is under intense scrutiny, some of the harshest light falls on heat treating.

838 How to Carburize a Finished Gear (March/April 1995)

Precise heat treatment plays an essential role in the production of quality carburized gears. Seemingly minor changes in the heat treating process can have significant effects on the quality, expense and production time of a gear, as we will demonstrate using a case study from one of our customer's gears.

839 What to Look For Before You Leap (March/April 1995)

Question: We are interested in purchasing our first gear hobbing machine. What questions should we ask the manufacturer, and what do we need to know in order to correctly specify the CNC hardware and software system requirements?

840 CNC Software Savvy (May/June 1995)

Question: When we purchase our first CNC gear hobbing machine, what questions should we ask about the software? What do we need to know to correctly specify the system requirements?

841 Long-Life, Low-cost, Near-Net-Shape forged Gears (May/June 1995)

Near-net gear forging today is producing longer life gears at significantly lower costs than traditional manufacturing techniques. Advances in forging equipment, controls and die-making capability have been combined to produce commercially viable near-net-shape gears in diameters up to 17" with minimum stock allowances. These forged gears require only minimal finishing to meet part tolerance specifications.

842 Eco-Friendly Cutting Fluids (May/June 1995)

Okay, so you want to make some high quality gears for your customers, and you want to make a profit for your company, but you don't want to make a mess of the environment. What can you do?

843 EHL Film Thickness, Additives and Gear Surface Fatigue (May/June 1995)

Aircraft transmissions for helicopters, turboprops and geared turbofan aircraft require high reliability and provide several thousand hours of operation between overhauls. In addition, They should be lightweight and have very high efficiency to minimize operating costs for the aircraft.

844 Our Experts Discuss... (March/April 1991)

Question: I have just become involved with the inspection of gears in a production operation and wonder why the procedure specifies that four involute checks must be made on each side of the tooth of the gear being produced, where one tooth is checked and charted in each quadrant of the gear. Why is this done? These particular gears are checked in the pre-shaved, finish-shaved, and the after-heat-treat condition, so a lot of profile checking must be done.

845 Synthesis of Spiral Bevel Gears (March/April 1991)

There are different types of spiral bevel gears, based on the methods of generation of gear-tooth surfaces. A few notable ones are the Gleason's gearing, the Klingelnberg's Palloid System, and the Klingelnberg's and Oerlikon's Cyclo Palliod System. The design of each type of spiral bevel gear depends on the method of generation used. It is based on specified and detailed directions which have been worked out by the mentioned companies. However, there are some general aspects, such as the concepts of pitch cones, generating gear, and conditions of force transmissions that are common for all types of spiral bevel gears.

846 A Proposed Life Calculation for Micropitting (November/December 2011)

If you make hardened gears and have not seen any micropitting, then you haven’t looked closely enough. Micropitting is one of the modes of failure that has more recently become of concern to gear designers and manufacturers. Micropitting in itself is not necessarily a problem, but it can lead to noise and sometimes other more serious forms of failure. Predicting when this will occur is the challenge facing designers.

847 Practical Analysis of Highly-Loaded Gears by Using the Modified-Scoring Index Calculation Method (September/October 1986)

The power of high speed gears for use in the petrochemical industry and power stations is always increasing. Today gears with ratings of up to 70,000kW are already in service. For such gears, the failure mode of scoring can become the limiting constraint. The validity of an analytical method to predict scoring resistance is, therefore, becoming increasingly important.

848 A Wheel Selection Technique for Form Gear Grinding (May/June 1986)

Until recently, form gear grinding was conducted almost exclusively with dressable, conventional abrasive grinding wheels. In recent years, preformed, plated Cubic Boron Nitride (CBN) wheels have been introduced to this operation and a considerable amount of literature has been published that claim that conventional grinding wheels will be completely replaced in the future. The superior machining properties of the CBN wheel are not disputed in this paper.

849 Identification of Gear Noise with Single Flank Composite Measurement (May/June 1986)

Anyone involved in the design, manufacture and use of gears is concerned with three general characteristics relative to their application: noise, accuracy, and strength or surface durability. In the article, we will be dealing with probably the most aggravating of the group, gear noise.

850 Bevel Gear Development and Testing Procedure (July/August 1986)

The most conclusive test of bevel and hypoid gears is their operation under normal running conditions in their final mountings. Testing not only maintains quality and uniformity during manufacture, but also determines if the gears will be satisfactory for their intended applications.

851 Engineering Constants (July/August 1986)

Below are listed a variety of commonly used constants arranged numerically to permit ease of reference. Wherever an asterisk (*) is shown, the constant is exact as given, it being generally a mathematical constant or one fixed by definition. In cases where the first constant listed is followed by another in parenthesis, the first is the round number generally used, while the second is the more exact value.

852 Viewpoint (July/August 1986)

Since we are a high volume shop, we were particularly interested in Mr. Kotlyar's article describing the effects of hob length on production efficiency which appeared in the Sept/Oct issue of Gear Technology. Unfortunately, some readers many be unnecessarily deterred from applying the analysis to their own situations by the formidabilty of the mathematical calculations. I am making the following small suggestion concerning the evaluation of the constant terms.

853 Effect of MoS2 Films on Scoring Resistance of Gears (July/August 1986)

Gears are currently run at high speed and under high load. It is a significant problem to develop lubricants and gears with high load-carrying capacity against scoring. The particles of molybdenum disulfide have been considered to increase the scoring resistance of the gears. The wear characteristics and the scoring resistance of the gears lubricated with MoS2 paste and MoS2 powder have been investigated. (1) However, there are few investigations on the performance of the gears coated with MoS2 film with respect to scoring.

854 Mechanical Efficiency of Diffential Gearing (July/August 1986)

Mechanical efficiency is an important index of gearing, especially for epicyclic gearing. Because of its compact size, light weight, the capability of a high speed ratio, and the ability to provide differential action, epicyclic gearing is very versatile, and its use is increasing. However, attention should be paid to efficiency not only to save energy, but sometimes also to make the transmission run smoothly or to avoid a self-locking condition.

855 Improved Gear Life Through Controlled Shot Peening (September/October 1986)

The search for greater gear life involves improvement in cost, weight and increased power output. There are many events that affect gear life, and this paper addresses those relating to fatigue, gear tooth pitting, fatigue strength losses due to the heat treating processes and shot peening technique. The capability of shot peening to increase fatigue strength and surface fatigue life eliminate machine marks which cause stress risers, and to aid in lubrication when properly controlled, suggests increased use and acceptance of the process.

856 Tooth Strength Study of Spur Planet Gears (September/October 1986)

In the design of any new gear drive, the performance of previous similar designs is very carefully considered. In the course of evaluating one such new design, the authors were faced with the task of comparing it with two similar existing systems, both of which were operating quite successfully. A problem arose, however, when it was realized that the bending stress levels of the two baselines differed substantially. In order to investigate these differences and realistically compare them to the proposed new design, a three-dimensional finite-element method (FEM) approach was applied to all three gears.

857 Engineering Constants (September/October 1986)

Rules and Formula for Gear Sizes

858 Long on High Technology -- Short on High Technologists (September/October 1986)

At the present time, technology seems to be moving faster than our ability to educate people in its utilization. this is particularly true of the manufacturing engineering profession.

859 Curvic Coupling Design (November/December 1986)

Curvic Couplings were first introduced in 1942 to meet the need for permanent couplings and releasing couplings (clutches), requiring extreme accuracy and maximum load carrying capacity, together with a fast rate of production. The development of the Curvic Coupling stems directly from the manufacture of Zerol and spiral bevel gears since it is made on basically similar machines and also uses similar production methods. The Curvic Coupling can therefore lay claim to the same production advantages and high precision associated with bevel gears.

860 CNC Gear Shaping (March/April 1986)

Two major processes used for cutting gears, hobbing and shaping. This article describes advanced machine design and cutter materials for gear shaping.

861 Mirror Finishing of Tooth Surfaces Using A Trial Gear Grinder With Cubic-Boron-Nitride Wheel (November/December 1986)

In conventional gear grinders, grinding wheels with Alundum grains and a hardness of about 2000 HV have been used for finishing steel gears with hardnesses up to about 1000HV. In this case, the accuracy of the gears ground is greatly affected by wear of the grinding wheel because the difference in hardness is comparatively small when the gears are fully hardened.

862 Lubricant Jet Flow Phenomena in Spur and Helical Gears (January/February 1987)

In the gearing industry, gears are lubricated and cooled by various methods. At low to moderate speeds and loads, gears may be partly submerged in the lubricant which provides lubrication and cooling by splash lubrication. With splash lubrication, power loss increases considerably with speed. This is partially because of churning losses. It is shown that gear scoring and surface pitting can occur when the gear teeth are not adequately lubricated and cooled.

863 Gear Manufacturing Methods - Forming the Teeth (January/February 1987)

The forming of gear teeth has traditionally been a time-consuming heavy stock removal operation in which close tooth size, shape, runout and spacing accuracy are required. This is true whether the teeth are finished by a second forming operation or a shaving operation.

864 Stopping the Great American Giveaway (January/February 1987)

Inviting an American shipbuilding industry official to discuss the subject of meeting foreign competition is like inviting Jackie Gleason to speak on dieting. I am painfully aware of the commercial shipbuilding industry situation. Let me tell you a little about it.

865 The Effect of Reverse Hobbing at a High Speed (March/April 1987)

Today it is common practice when climb hobbing to keep the direction of the hob thread the same as that of the helical gear. The same generalization holds true for the mass production of gears for automobiles. It is the authors' opinion, however, that conventional hobbing with a reverse-handed hob is more effective for the high-speed manufacture of comparatively small module gears for automobiles. The authors have proven both experimentally and theoretically that reverse-handed conventional hobbing, using a multi-thread hob with a smaller diameter is very effective for lengthening the life of the hob and for increasing cutting efficiency at high speeds.

866 Influence of Geometrical Parameters on the Gear Scuffing Criterion - Part I (March/April 1987)

The load capacity rating of gears had its beginning in the 18th century at Leiden University when Prof. Pieter van Musschenbroek systematically tested the wooden teeth of windmill gears, applying the bending strength formula published by Galilei one century earlier. In the next centuries several scientists improved or extended the formula, and recently a Draft International Standard could be presented.

867 Economics of CNC Gear Hobbing (March/April 1987)

NC and CNC metal cutting machines are among the most popular machine tools in the business today, There is also a strong trend toward using flexible machining centers and flexible manufacturing systems. The same trend is apparent in gear cutting. Currently the trend toward CNC tools has increased, and sophisticated controls and peripheral equipment for gear cutting machines are now available; however, the investment in a CNC gear machine has to be justified on the basis of economic facts as well as technical advantages.

868 Crowning: A Cheap Fix for Noise Reduction and Misalignment Problems and Applications (March/April 1987)

Noisy gear trains have been a common problem for gear designers for a long time. With the demands for smaller gear boxes transmitting more power at higher rpms and incumbent demands for greater efficiency, gear engineers are always searching for new ways to reduce vibration and limit noise without increasing costs.

869 Rotary Gear Honing (May/June 1987)

Rotary gear honing is a hard gear finishing process that was developed to improve the sound characteristics of hardened gears by: Removing nicks and burrs; improving surface finish; and making minor corrections in tooth irregularities caused by heat-treat distortion.

870 Gear Roll-Finishing (May/June 1987)

In this discussion of gear roll-finishing particular attention is called to the special tooth nomenclature resulting from the interaction between the rolling die teeth and the gear teeth. To eliminate confusion the side of a gear tooth that is in contact with the "approach" side of a rolling die tooth is also considered to be the approach side. The same holds true for the "trail" side. Thus, the side of the gear tooth that is in contact with the trail side of a rolling die is also considered to be the trail side.

871 Give Your Gears a Break - Select the Right Coupling! (May/June 1987)

How important is the right choice of coupling in determining successful machine design? Consider the following example. A transmission of appropriate size was needed to transfer the speed of the engine driver to that of the driven generator. The transmission was properly selected and sized to endure the rated power requirements indefinitely, but after only a short time in operation, it failed anyway. What happened? The culprit in the case was a coupling. It provided the necessary power and protection against misalignment but it lacked the ability to isolate the gears from the torque peaks of the diesel engine.

872 Gear Design Options (May/June 1987)

When specifying a complete gear design, the novice designer is confronted with an overwhelming and frequently confusing group of options which must be specified. This array of specifications range from the rather vague to the very specific.

873 Generating and Checking Involute Gear Teeth (May/June 1986)

It has previously been demonstrated that one gear of an interchangeable series will rotate with another gear of the same series with proper tooth action. It is, therefore, evident that a tooth curve driven in unison with a mating blank, will "generate" in the latter the proper tooth curve to mesh with itself.

874 Controlling Tooth Loads In Helical Gears (March/April 1986)

Helical gears can drive either nonparallel or parallel shafts. When these gears are used with nonparallel shafts, the contact is a point, and the design and manufacturing requirements are less critical than for gears driving parallel shafts.

875 Influence of Geometrical Parameters on the Gear Scuffing Criterion - Part 2 (May/June 1987)

In ParI 1 several scuffing (scoring) criteria were shown ultimately to converge into one criterion, the original flash temperature criterion according to Blok. In Part 2 it will be shown that all geometric influences may be concentrated in one factor dependent on only four independent parameters, of which the gear ratio, the number of teeth of the pinion, and the addendum modification coefficient of the pinion are significant.

876 The New Now: U.S. Workforce Sustainability (March/April 2012)

Faithful Addendum readers are accustomed to finding upbeat, whimsical and oddball stories about gears in this space. What follows is not about gears, exactly. Rather, it is, as opposed to the usual bleak news about America losing its manufacturing mojo—a look at a positive, hopeful development in that regard.

877 Vacuum Oil Quenching (November/December 2011)

The October 2011 issue of Gear Technology featured the article “Low-Distortion Heat Treatment of Transmission Components,” which covered the combination of low-pressure carburizing and high pressure gas quenching in an automotive environment. Here, heat treating expert Dan Herring explains why oil quenching is an appropriate choice for many applications.

878 Liebherr's LDF350 Offers Complete Machining in New Dimension (November/December 2011)

The objective, according to Dr.- Ing. Hansjörg Geiser, head of development and design for gear machines at Liebherr, was to develop and design a combined turning and hobbing machine in which turning, drilling and hobbing work could be carried out in the same clamping arrangement as the hobbing of the gearings and the subsequent chamfering and deburring processes.

879 Sicmat Releases Raso 200 Dynamic Shaving Machine (November/December 2011)

The Raso 200 Dynamic has been developed to offer all the characteristics of a gear shaving machine with a competitive price.

880 Load-Sharing Model for Polymer Cylindrical Gears (November/December 2011)

This paper presents an original method to compute the loaded mechanical behavior of polymer gears. Polymer gears can be used without lubricant, have quieter mesh, are more resistant to corrosion, and are lighter in weight. Therefore their application fields are continually increasing. Nevertheless, the mechanical behavior of polymer materials is very complex because it depends on time, history of displacement and temperature. In addition, for several polymers, humidity is another factor to be taken into account. The particular case of polyamide 6.6 is studied in this paper.

881 Flank Breakage on Gears for Energy Systems (November/December 2011)

Gear flank breakage can be observed on edge zone-hardened gears. It occurs, for example, on bevel gears for water turbines, on spur gears for wind energy converters and on single- and double-helical gears for other industrial applications.

882 Minimum Setup Time, Maximum Machining Capability (November/December 2011)

Hainbuch offers workholding solutions for United Gear.

883 Multifunctional Advancements (January/February 2012)

The latest in big gear machining with DMG/Mori Seiki.

884 Accelerating Validation Testing (January/February 2012)

Bringing new or improved products to market sooner has long been proven profitable for companies. One way to help shorten the time-to-market is to accelerate validation testing. That is, shorten the test time required to validate a new or improved product.

885 Ask the Expert - Bevel Gear Mounting (March/April 2012)

I am currently writing a design procedure for the correct method for setting up bevel gears in a gearbox for optimum performance...

886 Manufacturers Guide to Heat Treating Large Gears (March/April 2012)

The large gears found in mining, steel, construction, off-road, marine and energy applications—massive and robust in nature—need to tackle the greatest production demands. This, in turn, means that a special emphasis must be put on the heat treating methods used to increase the wear resistance and strength properties of gears this size.

887 Controlling Gear Distortion and Residual Stresses During Induction Hardening (March/April 2012)

Induction hardening is widely used in both the automotive and aerospace gear industries to minimize heat treat distortion and obtain favorable compressive residual stresses for improved fatigue performance. The heating process during induction hardening has a significant effect on the quality of the heat-treated parts. However, the quenching process often receives less attention even though it is equally important.

888 Single Flank Testing of Gears (May/June 1984)

Presumably, everyone who would be interested in this subject is already somewhat familiar with testing of gears by traditional means. Three types of gear inspection are in common use: 1) measurement of gear elements and relationships, 2) tooth contact pattern checks and 3) rolling composite checks. Single Flank testing falls into this last category, as does the more familiar Double Flank test.

889 Effect of Shot Peening on Surface Fatigue Life of Carburized and Hardened AISI 1910 Spur Gears (January/February 1986)

Gear surface fatigue endurance tests were conducted on two groups of 10 gears each of carburized and hardened AlSI 9310 spur gears manufactured from the same heat of material

890 Advantages of Titanium Nitride Coated Gear Tools (May/June 1984)

A brief introduction to the subject of Thin Film Coatings and their application to gear hobs and shaper cutters is followed by a detailed description of the Chemical Vapor Deposition Process and the Physical Vapor Deposition Process. Advantages and disadvantages of each of these processes is discussed. Emphasis is placed upon: application engineering of coated gear tools based on laboratory and field test results. Recommendations are suggested for tool design improvements and optimization of gear cutting operations using coated tools. Productivity improvements potentially available by properly utilizing coated tools are considered in terms of both tool cost and machining cost.

891 CNC Controlled CBN Form Grinding (May/June 1984)

Borazon is a superabrasive material originally developed by General Electric in 1969. It is a high performance material for machining of high alloy ferrous and super alloy materials. Borazon CBN - Cubic Born Nitride - is manufactured with a high temperature, high pressure process similar to that utilized with man-made diamond. Borazon is, next to diamond, the hardest abrasive known; it is more than twice as hard as aluminum oxide. It has an extremely high thermal strength compared to diamond. It is also much less chemically reactive with iron, cobalt or nickel alloys.

892 A Second Rate Society - Never (August/September 1984)

What was once recognized as the unique genius of America is now slipping away from us and, in many areas, is now seen as a "second rate" capability. Unless action is taken now, this country is in real danger of being unable to regain its supremacy in technological development and economic vigor. First Americans must understand the serious implications of the problem; and second, we must dedicate ourselves to national and local actions that will ensure a greater scientific and technological literacy in America.

893 Precision Forged Spiral Bevel Gears (August/September 1984)

A recent U.S. Army Tank-Automotive Command project, conducted by Battelle's Columbus Laboratories. successfully developed the methodology of CAD/CAM procedures for manufacturing dies (via EDM) for forging spiral bevel gears. Further, it demonstrated that precision forging of spiral bevel gears is a practical production technique. Although no detailed economic evaluation was made in this study, it is expected that precision forging offers an attractive alternative to the costly gear cutting operations for producing spiral bevel gears.

894 Economics of CNC Gear Gashing vs. Large D.P. Hobbing (August/September 1984)

Gear gashing is a gear machining process, very much like gear milling, utilizing the principle of cutting one or more tooth (or tooth space) at a time. The term "GASHING" today applies to the roughing, or roughing and finishing, of coarse diametral pitch gears and sprockets. Manufacturing these large coarse gears by conventional methods of rough and finish hobbing can lead to very long machining cycles and uneconomical machine utilization.

895 Single-Flank Testing (October/November 1984)

It was very interesting to see Robert Smith's article on single-flank testing of gears...

896 Endurance Limit for Contact Stress in Gears (October/November 1984)

With the publishing of various ISO draft standards relating to gear rating procedures, there has been much discussion in technical papers concerning the various load modification factors. One of the most basic of parameters affecting the rating of gears, namely the endurance limit for either contact or bending stress, has not, however, attracted a great deal of attention.

897 Cone Drive Double Enveloping Worm Gearing Design and Manufacturing (October/November 1984)

Worm gearing is of great antiquity, going back about 2100 years to Archimedes, who is generally acknowledged as its inventor. Archimedes' concept used an Archimedial spiral to rotate a toothed wheel. Development of the worm gearing principle progressed along conventional lines until about 500 years ago when Leonardo DaVinci evolved the double enveloping gear concept.

898 Gear Generating Using Rack Cutters (October/November 1984)

Universal machines capable of cutting both spur and helical gears were developed in 1910, followed later by machines capable of cutting double helical gears with continuous teeth. Following the initial success, the machines were further developed both in England and France under the name Sunderland, and later in Switzerland under the name Maag.

899 Scoring Load Capacity of Gears Lubricated with EP-Oils (October/November 1984)

The Integral Temperature Method for the evaluation of the scoring load capacity of gears is described. All necessary equations for the practical application are presented. The limit scoring temperature for any oil can be obtained from a gear scoring test.

900 The Process of Gear Shaving (May/June 1984)

Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index, helical angle, tooth profile and eccentricity.

901 Lower Grinding Costs and Better Workpiece Quality by High Performance Grinding with CBN Wheels (January/February 1986)

A considerable improvement in the performance of the machining of hard to grind materials can be achieved by means of CBN wheels.

902 Hard Cutting - A Competitive Process in High Quality Gear Production (May/June 1987)

The higher load carrying capacities, compact dimensions and longer life of hardened gears is an accepted fact in industry today. However, the costs involved in case hardening and subsequent finishing operations to achieve these advantages are considerable. For example, in order to achieve desired running properties on larger gears, it has been necessary to grind the tooth flanks. This costly operation can now be replaced, in many cases, by a new Hard Cutting (HC) process which permits the cutting of hardened gears while maintaining extremely low tooling costs.

903 Viewpoint (May/June 1987)

Joe Arvin comments on his recent trip to Scandinavia and how U.S. defense dollars are being spent overseas. J.D. Smith responds to an article on gear noise from the previous issue.

904 AGMA, ISO, and BS Gear Standards Part II - Pitting Resistance Ratings (January/February 1991)

In Part I differences in pitting ratings between AGMA 218, the draft ISO standard 6336, and BS 436:1986 were examined. In this part bending strength ratings are compared. All the standards base the bending strength on the Lewis equation; the ratings differ in the use and number of modification factors. A comprehensive design survey is carried out to examine practical differences between the rating methods presented in the standards, and the results are shown in graphical form.

905 Manufacturing of Forged and Extruded Gears (July/August 1990)

Traditional methods of manufacturing precision gears usually employ either hobbing or shaper cutting. Both of these processes rely upon generating the conjugate tooth form by moving the work-piece in a precise relation to the tool. Recently, attention has been given to forming gear teeth in a single step. Advantages to such a process include reduced production time, material savings, and improved performance characteristics. Drawbacks include complicated tool designs, non-uniformity of gears produced throughout the life of the tooling, and lengthy development times.

906 Hard Finishing and Fine Finishing Part 1 (September/October 1989)

Profitable hard machining of tooth flanks in mass production has now become possible thanks to a number of newly developed production methods. As used so far, the advantages of hard machining over green shaving or rolling are the elaborately modified tooth flanks are produced with a scatter of close manufacturing tolerances. Apart from an increase of load capacity, the chief aim is to solve the complex problem of reducing the noise generation by load-conditioned kinematic modifications of the tooth mesh. In Part II, we shall deal with operating sequences and machining results and with gear noise problems.

907 Gear Grinding Fundeamentals (September/October 1989)

This article deals with certain item to be taken into consideration for gear grinding, common problems that arise in gear grinding and their solutions. The discussion will be limited to jobbing or low-batch production environments, where experimental setup and testing is not possible for economic and other reasons.

908 Hard Finishing and Fine Finishing Part 2 (November/December 1989)

After shaping or hobbing, the tooth flanks must be either chamfered or duburred. Here it is paramount that the secondary burr produced will not be formed into the flank, but to the face of the gear, because during hardening, the secondary burr will straighten up and, due to its extreme hardness, will lead to excessive tool wear.

909 Achievable Carburizing Specifications (January/February 1990)

A widespread weakness of gear drawings is the requirements called out for carburize heat treating operations. The use of heat treating specifications is a recommended solution to this problem. First of all, these specifications guide the designer to a proper callout. Secondly, they insure that certain metallurgical characteristics, and even to some extent processing, will be obtained to provide the required qualities in the hardened gear. A suggested structure of carburizing specifications is give.

910 Shaper Cutters-Design & Applications Part 1 (March/April 1990)

Gear shaping is one of the most popular production choices in gear manufacturing. While the gear shaping process is really the most versatile of all the gear manufacturing methods and can cut a wide variety of gears, certain types of gears can only be cut by this process. These are gears closely adjacent to shoulders; gears adjacent to other gears, such as on countershafts; internal gears, either open or blind ended; crown or face gears; herringbone gears of the solid configuration of with a small center groove; rack; parts with filled-in spaces or teeth, such as are used in some clutches.

911 Influence of Lubrication on Pitting and Micropitting Resistance of Gears (March/April 1990)

Pitting and micropitting resistance of case-carburized gears depends on lubricants and lubrication conditions. Pitting is a form of fatigue damage. On this account a short time test was developed. The test procedure is described. The "pitting test" was developed as a short time test to examine the influence of lubricants on micropitting. Test results showing the influence of case-carburized gears on pitting and micropitting are presented.

912 Sustaining Expertise in the Gear Industry (June/July 2012)

Expertise is a resource that's hard to sustain. We're doing our part via our "Ask the Expert" feature. How about you?

913 Runout, Helix Accuracy and Shaper Cutters (June/July 2012)

Our experts discuss runout and helix accuracy, as well as the maximum number of teeth in a shaper cutter.

914 FZG Rig-Based Testing of Flank Load-Carrying Capacity Internal Gears (June/July 2012)

Micropitting, pitting and wear are typical gear failure modes that can occur on the flanks of slowly operated and highly stressed internal gears. However, the calculation methods for the flank load-carrying capacity have mainly been established on the basis of experimental investigations of external gears. This paper describes the design and functionality of the newly developed test rigs for internal gears and shows basic results of the theoretical studies. It furthermore presents basic examples of experimental test results.

915 The Geometric Design of Internal Gear Pairs (May/June 1990)

The paper describes a procedure for the design of internal gear pairs, which is a generalized form of the long and short addendum system. The procedure includes checks for interference, tip interference, undercutting, tip interference during cutting, and rubbing during cutting.

916 Shaper Cutters - Design & Application - Part 2 (May/June 1990)

Cutter Sharpening Cutter sharpening is very important both during manufacturing and subsequently in resharpening after dulling. Not only does this process affect cutter "over cutting edge" quality and the quality of the part cut, but it can also affect the manner in which chip flow takes place on the cutter face if the surface finished is too rough or rippled.

917 Transmission Errors and Bearing Contact of Spur, Helical, and Spiral Bevel Gears (July/August 1990)

An investigation of transmission errors and bearing contact of spur, helical, and spiral bevel gears was performed. Modified tooth surfaces for these gears have been proposed in order to absorb linear transmission errors caused by gear misalignment and to localize the bearing contact. Numerical examples for spur, helical, and spiral bevel gears are presented to illustrate the behavior of the modified gear surfaces with respect to misalignment and errors of assembly. The numerical results indicate that the modified surfaces will perform with a low level of transmission error in non-ideal operating environments.

918 Production Testing of a Chromium-Free Carburizing Grade Gear Steel (May/June 1989)

For many years chromium has been a popular alloy for heat treatable steels because of its contribution to hardenability more than offsets its costs. As a consequence, it is specified in such high-tonnage steel grades as the 5100, 4100, and 8600 series; and, as a result, about 15% of the annual U.S. consumption of chromium is used in constructional alloy steels.

919 Of Trees, Whales & Practicality (July/August 1990)

One of the hot items on the public agenda these days is "The Environment." Suddenly everyone wants to save the whales and the rain forest. Politicians, rock stars, and big business have all discovered that you can't get anything but good press for saying that you're in favor of trees and marine mammals.

920 Approximating an Involute Tooth Profile (September/October 1990)

On many occasions a reasonably approximate, but not exact, representation of an involute tooth profile is required. Applications include making drawings, especially at enlarged scale, and laser or EDM cutting of gears, molds, and dies used to produce gears. When numerical control (NC) techniques are to be used, a simple way to model an involute can make the NC programming task much easier.

921 Accurate and Fast Gear Trigonometry (September/October 1990)

An accurate and fast calculation method is developed to determine the value of a trigonometric function if the value of another trigonometric function is given. Some examples of conversion procedures for well-known functions in gear geometry are presented, with data for accuracy and computing time. For the development of such procedures the complete text of a computer program is included.

922 Limitations of Worm and Worm Gear Surfaces in Order to Avoid Undercutting (November/December 1990)

The dimensions of the worm and worm gear tooth surfaces and some of the worm gear drive parameters must be limited in order to avoid gear undercutting and the appearance of the envelope of lines of contact on the worm surface. The author proposes a method for the solution of this problem. The relations between the developed concept and Wildhaber's concept of the limit contact normal are investigated. The results of computations are illustrated with computer graphics.

923 Fundamentals of Bevel Gear Hard Cutting (November/December 1990)

Some years back, most spiral bevel gear sets were produced as cut, case hardened, and lapped. The case hardening process most frequently used was and is case carburizing. Many large gears were flame hardened, nitrided, or through hardened (hardness around 300 BHN) using medium carbon alloy steels, such as 4140, to avoid higher distortions related to the carburizing and hardening process.

924 AGMA, ISO, and BS Gear Standards Part I - Pitting Resistance Ratings (November/December 1990)

A study of AGMA 218, the draft ISO standard 6336, and BS 436: 1986 methods for rating gear tooth strength and surface durability for metallic spur and helical gears is presented. A comparison of the standards mainly focuses on fundamental formula and influence factors, such as the load distribution factor, geometry factor, and others. No attempt is made to qualify or judge the standards other than to comment on the facilities or lack of them in each standard reviewed. In Part I a comparison of pitting resistance ratings is made, and in the subsequent issue, Part II will deal with bending stress ratings and comparisons of designs.

925 The Effects of Surface Hardening on the Total Gear Manufacturing System (January/February 1991)

Carburized and hardened gears have optimum load-carrying capability. There are many alternative ways to produce a hard case on the gear surface. Also, selective direct hardening has some advantages in its ability to be used in the production line, and it is claimed that performance results equivalent to a carburized gear can be obtained. This article examines the alternative ways of carburizing, nitriding, and selective direct hardening, considering equipment, comparative costs, and other factors. The objective must be to obtain the desired quality at the lowest cost.

926 The Winds of Change (January/February 1991)

Nashville - One of the highlights of this year's SME Advanced Gear Processing and Manufacturing Clinic was a tour of the new GM Saturn automobile manufacturing plant outside the city. There in the Tennessee hills is a hopeful vision of the future of the American automobile industry. It may well be the future of American large-scale manufacturing in general.

927 AGMA Responds to Gear Standards Article (January/February 1991)

The authors of last issue's article comparing AGMA, ISO and BS methods for Pitting Resistance Ratings are commended. Trying to compare various methods of rating gears is like hitting a moving target in a thick forest. The use of different symbols, presentations, terminology, and definitions in these standards makes it very difficult. But the greatest problem lies with the authors' use of older versions of these documents. ISO drafts and AGMA standards have evolved at the same time their work was accomplished and edited.

928 Influence of CBN Grinding on Quality and Endurance of Drive Train Components (January/February 1991)

The merits of CBN physical characteristics over conventional aluminum oxide abrasives in grinding performance are reviewed. Improved surface integrity and consistency in drive train products can be achieved by the high removal rate of the CBN grinding process. The influence of CBN wheel surface conditioning procedure on grinding performance is also discussed.

929 The Marketing Menagerie: What's Right For You (January/February 1991)

You get calls and letters every day from people wanting you to use their ad agency, their direct mail program, their p.r. or marketing firm to promote your business. It seems everyone wants you to spend your money to communicate to your prospects and customers. But what's the best method for you?

930 What Is Runout, And Why Should I Worry About It (January/February 1991)

Runout is a troublemaker! Good shop practice for the manufacture or inspection of gears requires the control of runout. Runout is a characteristic of gear quality that results in an effective center distance variation. As long as the runout doesn't cause loss of backlash, it won't hurt the function of the gear, which is to transmit smooth motion under load from one shaft to another. However, runout does result in accumulated pitch variation, and this causes non-uniform motion, which does affect the function of the gears. Runout is a radial phenomenon, while accumulated pitch variation is a tangential characteristic that causes transmission error. Gears function tangentially. It is also possible to have a gear with accumulated pitch variation, but little or no runout.

931 Estimating Hobbing Times (July/August 1989)

Hobbing is a continuous gear generation process widely used in the industry for high or low volume production of external cylindrical gears. Depending on the tooth size, gears and splines are hobbed in a single pass or in a two-pass cycle consisting of a roughing cut followed by a finishing cut. State-of-the-art hobbing machines have the capability to vary cutting parameters between first and second cut so that a different formula is used to calculate cycle times for single-cut and double-cut hobbing.

932 Deburring & Finishing Gears with Power Brushes (March/April 1989)

Why Brushes? In this age of hi-tech, robots, automatic machines, machining cells, etc., is there a niche somewhere for power brushes? Let me answer by asking another question. What tool does the gear manufacturer have in his arsenal that allows him to deburr green gears, hardened gears, hobbed gears, ground gears and shaved gears? What tool allows him to deburr powder metal gears - green and sintered - brass gears, bronze gears, stainless gears made of exotic materials such as inconel, waspaloy, or hastaloy, and fiber and plastic gears? How about spur gears, helical gears, sprockets, both internal and external splines, clutch teeth and pump gears?

933 Longitudinal Load Distribution Factor for Straddle- and Overhang-Mounted Spur Gears (July/August 1987)

A pair of spur gears generally has an effective lead error which is caused, not only by manufacturing and assembling errors, but also by the deformations of shafts, bearings and housings due to the transmitted load. The longitudinal load distribution on a contact line of the teeth of the gears is not uniform because of the effective lead error.

934 Hard Gear Finishing (March/April 1988)

Hard Gear Finishing (HGF), a relatively new technology, represents an advance in gear process engineering. The use of Computer Numerical Controlled (CNC) equipment ensures a high precision synchronous relationship between the tool spindle and the work spindle as well as other motions, thereby eliminating the need for gear trains. A hard gear finishing machine eliminates problems encountered in two conventional methods - gear shaving, which cannot completely correct gear errors in gear teeth, and gear rolling, which lacks the ability to remove stock and also drives the workpiece without a geared relationship to the master rolling gear. Such a machine provides greater accuracy, reducing the need for conventional gear crowning, which results in gears of greater face width than necessary.

935 Cutting Fluid Selection and Process Controls for the Gear Manufacturing Industry (July/August 1987)

The last decade has been a period of far-reaching change for the metal working industry. The effect of higher lubricant costs, technical advances in machine design and increasing competition are making it essential that manufacturers of gears pay more attention to testing, selecting and controlling cutting fluid systems. Lubricant costs are not a large percentage of the process cost relative to items such as raw materials, equipment and labor, and this small relative cost has tended to reduce the economic incentive to evaluate and to change cutting fluids.

936 Viewpoint (July/August 1987)

In the May/June Issue of your excellent magazine. Mr. Stan Jakuba discusses a serious problem, not only for the gear industry, but any machinery where fluctuating torque is encountered. I would like to make the following comments to his article...

937 Effects of Hob Quality and Resharpening Errors on Generating Accuracy (September/October 1987)

The modern day requirement for precision finished hobbed gears, coupled with the high accuracy characteristics of modern CNC hobbing machines, demands high tool accuracy.

938 Selection of a Proper Ball Size to Check an Involute Spur or Helical Cear Tooth (September/October 1987)

A much-used method for checking the tooth thickness of an involute gear tooth is to measure the dimension over two balls placed in most nearly opposite spaces in the case of external gears, and the dimension between the balls in the case of internal gears. This measurement is then checked against a pre-calculated dimension to denote an acceptable part.

939 Finishing of Gears by Ausforming (November/December 1987)

Almost all machines or mechanical systems contain precision contact elements such as bearings, cams, rears, shafts, splines and rollers. These components have two important common requirements: first, they must possess sufficient mechanical properties, such as, high hardness, fatigue strength and wear resistance to maximize their performance and life; second, they must be finished to close dimensional tolerances to minimize noise, vibration and fatigue loading.

940 Selection of Hobbing Data (November/December 1987)

The art of gear hobbing has advanced dramatically since the development and introduction of unique machine and tool features such as no backlash, super rigidity, automatic loading of cutting tools, CNC controls, additional machine power and improved cutter materials and coatings. It is essential to utilize all these features to run the machine economically.

941 Good Gears Start With Good Blanks (November/December 1987)

The quality of the finished gear is influenced by the very first machining operations of the blank. Since the gear tooth geometry is generated on a continuously rotating blank in hobbing or shaping, it is important that the timed relationship between the cutter and workpiece is correct. If this relationship is disturbed by eccentricities of the blank to its operating centerline, the generated gear teeth will not be of the correct geometry. During the blanking operations, the gear's centerline and locating surfaces are established and must be maintained as the same through the following operations that generate the gear teeth.

942 Viewpoint (November/December 1987)

Letters to the editor covering a variety of subjects, including computers in gear design, couplings and more.

943 Computer Aided Design for Gear Shaper Cutters (November/December 1987)

Computer programs have been developed to completely design spur and helical gear shaper cutters starting from the specifications of the gear to be cut and the type of gear shaper to be used. The programs generate the working drawing of the cutter and, through the use of a precision plotter, generate enlarge scaled layouts of the gear as produced by the cutter and any other layouts needed for its manufacture.

944 The Use of Boundary Elements For The Determination of the AGMA Geometry Factor (January/February 1988)

The geometry factor, which is a fundamental part of the AGMA strength rating of gears, is currently computed using the Lewis parabola which allows computation of the Lewis form factor.(1) The geometry factor is obtained from this Lewis factor and load sharing ratio. This method, which originally required graphical construction methods and more recently has been computerized, works reasonably well for external gears with thick rims.(2-6) However, when thin rims are encountered or when evaluating the strength of internal gears, the AGMA method cannot be used.

945 Contact Surface Topology of Worm Gear Teeth (March/April 1988)

Among the various types of gearing systems available to the gear application engineer is the versatile and unique worm and worm gear set. In the simpler form of a cylindrical worm meshing at 90 degree axis angle with an enveloping worm gear, it is widely used and has become a traditional form of gearing. (See Fig. 1) This is evidenced by the large number of gear shops specializing in or supplying such gear sets in unassembled form or as complete gear boxes. Special designs as well as standardized ratio sets covering wide ratio ranges and center distanced are available with many as stock catalog products.

946 High Tech Manufacturing--Challenges for the 1990s (March/April 1988)

This issue's editorial is a reprint of the keynote address given by Michael Goldstein at the Computer Aided Gear Design Seminar held at the University of Northern Iowa, Cedar Falls, IA on November 9, 1987.

947 The Wafer Shaper Cutter (March/April 1989)

In 1985 a new tooling concept for high volume gear production was introduced to the gear manufacturing industry. Since then this tool, the wafer shaper cutter, has proven itself in scores of applications as a cost-effective, consistent producer of superior quality parts. This report examines the first high-production installation at the plant of a major automotive supplies, where a line of twenty shapers is producing timing chain sprockets.

948 Computer-Aided Design of the Stress Analysis of an Internal Spur Gear (May/June 1988)

Although there is plenty of information and data on the determination of geometry factors and bending strength of external gear teeth, the computation methods regarding internal gear design are less accessible. most of today's designs adopt the formulas for external gears and incorporate some kind of correction factors for internal gears. However, this design method is only an approximation because of the differences between internal gears and external gears. Indeed, the tooth shape of internal gears is different from that of external gears. One has a concave curve, while the other has a convex curve.

949 Crisis and Challenge in American Education (May/June 1988)

"We have met the enemy and he is us," says Pogo, the cartoon character. The enemy is the crisis in our educational system, and "crisis" is the only term that accurately describes the situation. It is every bit as serious, if not more so, than the crisis that followed the Soviet launching of Sputnik in 1957 - and for many of the same reasons. Our failing public education system threatens our position int he global political and business arenas; and this time, it's not just the Soviets or the Japanese who need to be taken seriously as competitors. Every country int he world that graduates better prepared students than we do - and there are a great many of them - has us at a competitive disadvantage.

950 Curvilinear Cylindrical Gears (May/June 1988)

The curved tooth cylindrical gear is one of ancient design. Samples which date from the period of the Warring State (475-221 BC) have been excavated from archeological sites in China. One such sample is now on display in the Xi'an Clay figures of Warriors and Horses Exhibition Hall. This example is about 3/4" in diameter and made of bronze. It was used in the famous model, "Ancient Chinese Vehicle With a Wooden Figure Always Pointing to the South." Although this early gear is handmade and somewhat crude, it is a viable model.

951 Tooth Root Stresses of Spiral Bevel Gears (May/June 1988)

Service performance and load carrying capacity of bevel gears strongly depend on the size and position of the contact pattern. To provide an optimal contact pattern even under load, the gear design has to consider the relative displacements caused by deflections or thermal expansions expected under service conditions. That means that more or less lengthwise and heightwise crowning has to be applied on the bevel gear teeth.

952 Industry Forum (July/August 1988)

Letters to the editor on a variety of subjects, including couplings, gear planers and ausforming.

953 High Speed Hobbing of Gears With Shifted Profiles (July/August 1988)

The newer profile-shifted (long and short addendum) gears are often used as small size reduction gears for automobiles or motorcycles. The authors have investigated the damage to each cutting edge when small size mass-produced gears with shifted profiles are used at high speeds.

954 The Uses and Limitations of Transmission Error (July/August 1988)

The concept of "transmission error" is relatively new and stems from research work in the late 1950s by Gregory, Harris and Munro,(1) together with the need to check the accuracy of gear cutting machines. The corresponding commercial "single flank" testing equipment became available in the 1960s, but it was not until about ten years ago that it became generally used, and only recently has it been possible to test reliably at full load and full speed.

955 Enhanced Product Performance--Through CBN Grinding (September/October 1988)

Modern manufacturing processes have become an ally of the product designer in producing higher quality, higher performing components in the transportation industry. This is particularly true in grinding systems where the physical properties of CBN abrasives have been applied to improving cycle times, dimensional consistency, surface integrity and overall costs. Of these four factors, surface integrity offers the greatest potential for influencing the actual design of highly stressed, hardened steel components.

956 Crowned Spur Gears: Optimal Geometry and Generation (September/October 1988)

Involute spur gears are very sensitive to gear misalignment. Misalignment will cause the shift of the bearing contact toward the edge of the gear tooth surfaces and transmission errors that increase gear noise. Many efforts have been made to improve the bearing contact of misaligned spur gears by crowning the pinion tooth surface. Wildhaber(1) had proposed various methods of crowning that can be achieved in the process of gear generation. Maag engineers have used crowning for making longitudinal corrections (Fig. 1a); modifying involute tooth profile uniformly across the face width (Fig. 1b); combining these two functions in Fig. 1c and performing topological modification (Fig. 1d) that can provide any deviation of the crowned tooth surface from a regular involute surface. (2)

957 The Elementary Theory for the Synthesis of Constant Direction Pointing Chariots (or Rotation Neutralizers) (November/December 1988)

The south-pointing chariot exhibited at the Smithsonian Institution, Washington, D.C., (circa 2600 BC)is shown in Fig. 1. Although the mechanism is ancient, it is by no means either primitive or simplistic. The pin-tooth gears drive a complex system, wherein the monk on the top of the chariot continues to point in a preset direction, no matter what direction the vehicle in moved, without a slip of the wheels.(1)

958 Gear Tooth Profile Determination From Arbitrary Rack Geometry (November/December 1988)

This article describes a method of obtaining gear tooth profiles from the geometry of the rack (or hob) that is used to generate the gear. This method works for arbitrary rack geometries, including the case when only a numerical description of the rack is available. Examples of a simple rack, rack with protuberances and a hob with root chamfer are described. The application of this technique to the generation of boundary element meshes for gear tooth strength calculation and the generation of finite element models for the frictional contact analysis of gear pairs is also described.

959 Fillet Geometry of Ground Gear Teeth (January/February 1989)

This article investigates fillet features consequent to tooth grinding by generating methods. Fillets resulting from tooth cutting and tooth grinding at different pressure angles and with different positions of grinding wheel are compared. Ways to improve the final fillet of the ground teeth with regard to tooth strength and noise, as well as the grinding conditions, are shown. "Undergrinding" is defined and special designs for noiseless gears are described.

960 Industry News (March/April 2020)

The complete Industry News section from the March/April issue of Gear Technology.