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1 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.

2 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...

3 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.

4 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.

5 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.

6 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.

7 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.

8 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.

9 Holroyd Launches New Gear Grinder (January/February 2005)

New machine promises DIN 2 accuracy and unique features at low cost.

10 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.

11 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.

12 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.

13 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.

14 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.

15 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.

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

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

17 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.

18 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.

19 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.

20 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.

21 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.

22 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.

23 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.

24 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.

25 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.

26 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.

27 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.

28 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.

29 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.

30 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.

31 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.

32 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.

33 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.

34 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.

35 Delivering Big Gears Fast (May 2013)

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

36 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.

37 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

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

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

39 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.

40 IMTS 2012 Product Preview (September 2012)

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

41 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.

42 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.

43 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.

44 Industry News (May 2014)

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

45 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.

46 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.

47 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.

48 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.

49 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.

50 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.

51 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.

52 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.

53 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.

54 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.

55 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.

56 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.

57 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.

58 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.

59 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.

60 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?

61 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.

62 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.

63 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.

64 The Kinematics of Conical Involute Gear Hobbing (July 2008)

Conical involute gears, also known as beveloid gears, are generalized involute gears that have the two flanks of the same tooth characterized by different base cylinder radii and different base helix angles.

65 GPSys Critical to Spiral Bevel Gear Life (September/October 2008)

Impact Technologies considers commercial version of software package.

66 Development of Conical Involute Gears (Beveloids) for Vehicle Transmissions (November/December 2005)

Conical involute gears (beveloids) are used in transmissions with intersecting or skewed axes and for backlash-free transmissions with parallel axes.

67 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.

68 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.

69 Good Basic Design or Sophisticated Flank Optimizations - Each at the Right Time (January/February 2005)

More strength, less noise. Those are two major demands on gears, including bevel and hypoid gears.

70 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.

71 The Road Leads Straight to Hypoflex (March/April 2010)

A new method for cutting straight bevel gears.

72 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.

73 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.

74 Zerol Bevel Gears: Tribology Aspects in Angular Transmission Systems, Part III (November/December 2010)

Zerol bevel gears are the special case of spiral bevel gears with a spiral angle of 0°. They are manufactured in a single-indexing face milling process with large cutter diameters, an extra deep tooth profile and tapered tooth depth.

75 Straight Bevel Gears (September/October 2010)

Tribology Aspects in Angular Transmission Systems, Part 2

76 Tribology Aspects in Angular Transmission Systems, Part 1 (August 2010)

"General Explanations on Theoretical Bevel Gear Analysis" is part 1 of an eight-part series from Gleason's Dr. Hermann Stadtfeld.

77 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.

78 Shorter Cycle Times for Carburizing: Dana Develops Atmosphere, Microwave-Based Process (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.

79 Gleason Cutter Head Improves Tool Life and Productivity (November/December 2009)

The Pentac Plus is the latest generation of Gleason’s Pentac bevel gear cutting system. It is designed to allow much higher tool life and improved productivity, especially for cutters using multiple face blade geometry.

80 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.

81 Hypoloid Gear with Small Shaft Angles and Zero-to-Large Offsets (November/December 2009)

Beveloid gears are used to accommodate a small shaft angle. The manufacturing technology used for beveloid gearing is a special setup of cylindrical gear cutting and grinding machines. A new development, the so-called Hypoloid gearing, addresses the desire of gear manufacturers for more freedoms. Hypoloid gear sets can realize shaft angles between zero and 20° and at the same time, allow a second shaft angle (or an offset) in space that provides the freedom to connect two points in space.

82 Spiral Bevel and Hypoid Gear Cutting Technology Update (July 2007)

Spiral bevel and hypoid gear cutting has changed significantly over the years. The machines, tools, processes and coatings have steadily advanced.

83 New Developments in TCA and Loaded TCA (May 2007)

How the latest techniques and software enable faster spiral bevel and hypoid design and development.

84 Influence of Relative Displacements Between Pinion and Gear on Tooth Root Stresses of Spiral Bevel Gears (July/August 1985)

The manufacturing quality of spiral bevel gears has achieved a very high standard. Nevertheless, the understanding of the real stress conditions and the influences. of certain parameters is not satisfactory.

85 Analyzing Gear Tooth Stress as a Function of Tooth Contact Pattern Shape and Position (January/February 1985)

The development of a new gear strength computer program based upon the finite element method, provides a better way to calculate stresses in bevel and hypoid gear teeth. The program incorporates tooth surface geometry and axle deflection data to establish a direct relationship between fillet bending stress, subsurface shear stress, and applied gear torque. Using existing software links to other gear analysis programs allows the gear engineer to evaluate the strength performance of existing and new gear designs as a function of tooth contact pattern shape, position and axle deflection characteristics. This approach provides a better understanding of how gears react under load to subtle changes in the appearance of the no load tooth contact pattern.

86 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.

87 Assembling Spiral Gears: Double Taper Can Be Double Trouble (January/February 2006)

Bevel gear systems are particularly sensitive to improper assembly. Slight errors in gear positioning can turn a well-designed, quality manufactured gear set into a noisy, prone-to-failure weak link in your application.

88 Evaluation of a Low-Noise, Formate Spiral Bevel Gear Set (January/February 2008)

Studies to evaluate low-noise Formate spiral bevel gears were performed. Experimental tests were conducted on a helicopter transmission test stand...

89 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.

90 Bevel Gears: Optimal High Speed Cutting (August 2007)

This article presents a summary of all factors that contribute to efficient and economical high-speed cutting of bevel and hypoid gears.

91 Beveloid & Hypoloid Gears (May 2011)

Beveloids are helical gears with nonparallel shafts, with shaft angles generally between 5 degrees and 15 degrees. This is part VI in the Tribology Aspects in Angular Transmission Systems Series

92 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.

93 Cutting Low-Pich-Angle Bevel Gears; Worm Gears & 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?

94 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.

95 Design Guidelines for High-Capacity Bevel Gear Systems (January/February 1992)

The design of any gearing system is a difficult, multifaceted process. When the system includes bevel gearing, the process is further complicated by the complex nature of the bevel gears themselves. In most cases, the design is based on an evaluation of the ratio required for the gear set, the overall envelope geometry, and the calculation of bending and contact stresses for the gear set to determine its load capacity. There are, however, a great many other parameters which must be addressed if the resultant gear system is to be truly optimum. A considerable body of data related to the optimal design of bevel gears has been developed by the aerospace gear design community in general and by the helicopter community in particular. This article provides a summary of just a few design guidelines based on these data in an effort to provide some guidance in the design of bevel gearing so that maximum capacity may be obtained. The following factors, which may not normally be considered in the usual design practice, are presented and discussed in outline form: Integrated gear/shaft/bearing systems Effects of rim thickness on gear tooth stresses Resonant response

96 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.

97 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.

98 Tooth Contact Shift in Loaded Spiral Bevel Gears (November/December 1992)

An analytical method is presented to predict the shifts of the contact ellipses on spiral bevel gear teeth under load. The contact ellipse shift is the motion of the point to its location under load. The shifts are due to the elastic motions of the gear and pinion supporting shafts and bearings. The calculations include the elastic deflections of the gear shafts and the deflections of the four shaft bearings. The method assumes that the surface curvature of each tooth is constant near the unloaded pitch point. Results from these calculations will help designers reduce transmission weight without seriously reducing transmission performance.

99 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?

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

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

101 Differential Gears (October 2012)

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

102 Meshing of a Spiral Bevel Gear Set With 3-D Finite Element Analysis (March/April 1997)

Recent advances in spiral bevel gear geometry and finite element technology make it practical to conduct a structural analysis and analytically roll the gear set through mesh. With the advent of user-specific programming linked to 3-D solid modelers and mesh generators, model generation has become greatly automated. Contact algorithms available in general purpose finite element codes eliminate the need for the use and alignment of gap elements. Once the gear set it placed in mesh, user subroutines attached to the FE code easily roll it through mesh. The method is described in detail. Preliminary result for a gear set segment showing the progression of the contact line load is given as the gears roll through mesh.

103 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.

104 Maximum Life Spiral Bevel Reduction Design (September/October 1993)

Optimization is applied to the design of a spiral bevel gear reduction for maximum life at a given size. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial values. Gear tooth bending strength and minimum contact ration under load are included in the active constraints. The optimal design of the spiral bevel gear reduction includes the selection of bearing and shaft proportions in addition to gear mesh parameters. System life is maximized subject to a fixed back-cone distance of the spiral bevel gear set for a specified speed ratio, shaft angle, input torque and power. Significant parameters in the design are the spiral angle, the pressure angle, the numbers of teeth on the pinion and gear and the location and size of the four support bearings. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for gradient optimization. After finding the continuous optimum, a designer can analyze near-optimal designs for comparison and selection. Design examples show the influence of the bearing lives on the gear parameters in the optimal configurations. For a fixed back-cone distance, optimal designs with larger shaft angles have larger service lives.

105 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.

106 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.

107 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...

108 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.

109 Reliable and Efficient Skiving (September 2011)

Klingelnberg's new tool and machine concept allow for precise production.

110 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.

111 Hypoid Gears: Tribology Aspects in Angular Transmission Systems, Part VII (June/July 2011)

Hypoid gears are the paragon of gearing. To establish line contact between the pitches in hypoid gears, the kinematically correct pitch surfaces have to be determined based on the axoids. In cylindrical and bevel gears, the axoids are identical to the pitch surfaces and their diameter or cone angle can be calculated simply by using the knowledge about number of teeth and module or ratio and shaft angle. In hypoid gears, a rather complex approach is required to find the location of the teeth—even before any information about flank form can be considered. This article is part seven of an eight-part series on the tribology aspects of angular gear drives.

112 A Computer Solution for the Dynamic Load, Lubricant Film Thickness, and Surface Temperatures in Spiral-Bevel Gears (March/April 1986)

Spiral-bevel gears, found in many machine tools, automobile rear-axle drives, and helicopter transmissions, are important elements for transmitting power.

113 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.

114 Engineering Constants (May/June 1987)

Rules and Formula for worm gears, bevel gears and strength of gear teeth.

115 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.

116 Kinematic Analysis of Robotic Bevel-Gear Trains (November/December 1986)

In robot configurations it is desirable to be able to obtain an arbitrary orientation of the output element or end-effector. This implies a minimum of two independent rotations about two (generally perpendicular) intersecting axes. If, in addition, the out element performs a mechanical task such as in manufacturing or assembly (e.g., drilling, turning, boring, etc.) it may be necessary for the end-effector to rotate about its axis. If such a motion is to be realized with gearing, this necessitates a three-degree-of-freedom, three-dimensional gear train, which provides a mechanical drive of gyroscopic complexity; i.e., a drive with independently controlled inputs about three axes corresponding to azimuth, nutation, and spin.

117 Pressure Angle Changes in the Transverse Plane for Circular Cut Spiral Bevel Gears (September/October 1986)

Recently it has been suggested that the transverse plane may be very useful in studying the kinematics and dynamics of spiral bevel gears. The transverse plane is perpendicular to the pitch and axial planes as shown in Fig. 1. Buckingham has suggested that a spiral bevel gear may be viewed as a limited form of a "stepped" straight-tooth gear as in Fig. 2. The transverse plane is customarily used in the study of straight toothed bevel gears.

118 Gears for Nonparallel Shafts (September/October 1986)

Transmission of power between nonparallel shafts is inherently more difficult than transmission between parallel shafts, but is justified when it saves space and results in more compact, more balanced designs. Where axial space is limited compared to radial space, angular drives are preferred despite their higher initial cost. For this reason, angular gear motors and worm gear drives are used extensively in preference to parallel shaft drives, particularly where couplings, brakes, and adjustable mountings add to the axial space problem of parallel shaft speed reducers.

119 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.