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hobbing machines - Search Results

Related Buyers Guide Categories

Hobbers & Hobbing Machines
Spline Hobbing Machines

Related Companies

Barber-Colman, Div of Bourn & Koch
Bourn & Koch designs and builds new machines for hobbing, grinding, turning and shaping. We also provide parts and service for legacy machine tool products, including Barber-Colman, Fellows and many others.

Bourn & Koch Inc.
Established in 1974, Bourn & Koch Inc. is a manufacturer of industrial machine tools for a wide variety of industries. Bourn & Koch Inc. expanded in the new machine market by purchasing Barber-Colman Machine Tool Division in 1985, by purchasing Fellows and Roto-Technology in 2002, and by purchasing DeVlieg Bullard in 2004.

Fellows Machine Tools
We long have been known for manufacturing new hobbing horizontal hobbing machines under our Bourn & Koch name. We also build new Fellows Gear Shapers, Motch Vertical Turning machines, Springfield Vertical OD/ID Grinding machines, and Blanchard Rotary Grinding Machines.

Klingelnberg AG
Klingelnberg is a world leader in the development, manufacture and sale of gear production machinery and related equipment.

Liebherr America
Liebherr Gear Technology Co. is your North American access point to a broad range of technically advanced gear manufacturing technologies and processes.

Star Cutter Co.
Headquartered in Farmington Hills, MI, StarCut Sales, Inc. is a wholly owned subsidiary of Star Cutter Company and is a partner in the Star SU LLC enterprise for marketing, sales, and service. Through Star SU and StarCut Sales, Inc.'s international organization Star Cutter Company markets and services its products in North America, South America, Europe and the Far East.

Star SU LLC
Star SU LLC provides the latest in gear and rotor manufacturing technology by offering a wide variety of gear cutting machinery, tools and services.

Höfler - A Brand of Klingelnberg
Klingelnberg GmbH

Articles About hobbing machines


1 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?

2 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?

3 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?

4 Product News (May 2009)

The complete Product News section from the May 2009 issue of Gear Technology.

5 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.

6 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.

7 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.

8 Gear Hobbing Technology Update (June/July 2011)

Q&A with Liebherr's Dr. Alois Mundt.

9 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.

10 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).

11 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.

12 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.

13 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.

14 Don't Panic (July/August 2000)

I'm a big believer in the value of IMTS as a marketplace where gear manufacturers can go and look at the latest machine tools and processes; compare hobbing machines, gear grinders and inspection equipment; see turning, milling or grinding machines in action; and ask questions of the various vendors all in one place. This year's IMTS promised to be the biggest ever, and I have no doubt that it will be a valuable experience to those who go there looking for ways to improve the way they manufacture products.

15 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.

16 Reliable and Efficient Skiving (September 2011)

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

17 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.

18 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.

19 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.

20 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.

21 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.

22 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.

23 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.

24 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.

25 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.

26 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.

27 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.

28 Progress in Gear Milling (January/February 2013)

Sandvik presents the latest in gear milling technologies.

29 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.

30 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).

31 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.

32 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.

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

A new method for cutting straight bevel gears.

34 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.

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

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

36 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.

37 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.

38 IMTS 2012 Product Preview (September 2012)

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

39 IMTS 2012 Product Preview (August 2012)

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

40 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.

41 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.

42 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.

43 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.

44 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.

45 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.

46 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.

47 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

48 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.

49 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.

50 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.

51 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.

52 CNC Basics (January/February 1995)

NC and CNC machines are at the heart of manufacturing today. They are the state-of-the-art equipment everybody has (or is soon going to get) that promise to lower costs, increase production and turn manufacturers into competitive powerhouses. Like many other high tech devices (such as microwaves and VCRs), lots of people have and use them - even successfully - without really knowing much about how they operate. But upgrading to CNC costs a lot of money, so it's crucial to separate the hype from the reality.

53 CNC Gear Manufacturing - Where Are We Now (January/February 1995)

These days it's hard to get through breakfast without reading or hearing another story about how the computer is changing the way we live, sleep, eat, breathe, make things and do business. The message is that everything is computerized now, or, if it isn't, it will be by next Tuesday at the latest, Well, maybe.

54 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.

55 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.

56 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.

57 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.

58 New Gear Developments at IMTS (November/December 1996)

The International Manufacturing Technology Show provided one of the biggest ever marketplaces for buying and selling gear-making equipment, with 121601 attenders, making it the largest IMTS ever. The show took place September 4-11 at McCormick Place in Chicago, IL.

59 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.

60 Computers and Automation Lead IMTS Innovations (November/December 1994)

Robots, computers and other signs of high technology abounded at IMTS 94, supporting the claim by many that this was one of the best shows ever. Many of the machines on display had so many robotic attachments and computer gizmos that they looked more like they belonged in some science fiction movie than on the floor of a machine shop.

61 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.

62 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.

63 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.

64 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.

65 Finish Hobbing Crowned Helical Gears without Twist (January/February 2006)

New tool from LMT-Fette provides combination of operations.

66 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.

67 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.

68 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.

69 LMT Fette Introduces SpeedCore (October 2011)

New material technology allows for more efficient and flexible hobbing.

70 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.

71 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.

72 Optimal Choice of the Shaft Angle for Involute Gear 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.

73 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.

74 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.

75 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.

76 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.

77 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.

78 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.

79 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.

80 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.

81 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.

82 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.

83 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.

84 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.

85 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.

86 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.

87 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.

88 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?

89 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.

90 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?

91 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.).

92 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.

93 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.

94 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.

95 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).

96 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?

97 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?

98 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.

99 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.

100 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.

101 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.

102 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.

103 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.

104 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.

105 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.

106 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.

107 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.

108 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.

News Items About hobbing machines

1 Koepfer Introduces New 'H' Series Hobbing Machines (November 10, 2014)
Koepfer America, L.L.C., introduces the CLC “H” series of heavy duty horizontal gear hobbing machines to the North American g... Read News