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Articles About PM
Design innovation, superior engineering properties, high end-market visibility and sustainability distinguish the winners of the 2011 Design Excellence awards, the annual powder metallurgy (PM) design competition sponsored by the Metal Powder Industries Federation.
For heat treatment of tool and alloy steels, the end-user has a wide range of basic types of heat treating equipment to choose from. This article reviews them and details the criteria that must be considered in selecting equipment for a specific application. In making this choice, the most important criterion must be the quality of the tool or part after processing.
Capstan Atlantic, located in Wrentham, Massachusetts, produces powder metal gears, sprockets and complex structural components. The company has provided unique powder metal products in a variety of industries including automotive, business machines, appliances, lawn and garden equipment and recreational vehicles.
Question: We just received permission to purchase our first CNC gear inspection system. With capital approvals so hard to come by, especially for inspection equipment, I want to be sure to purchase a system I can count of for years to come. My past experience with purchasing CNC equipment has shown me that serviceability of the computer and the CNC controller portion of the system can be a problem in just a few years because of the obsolescence factor. What information do I need to look for when selecting a supplier to reduce the risk of obsolescence, as well as to reduce the long-term servicing costs in the computer and controls portion of the system?
Except for higher-end gear applications found in automotive and aerospace transmissions, for example, high-performance, sintered-steel gears match wrought-steel gears in strength and geometrical quality. The enhanced P/M performance is due largely to advances in powder metallurgy over last two decades, such as selective surface densification, new materials and lubricants for high density and warm-die pressing. This paper is a review of the results of a decade of research and development of high- performance, sintered-steel gear prototypes.
The implementation of powder metal (PM)components in automotive applications increases continuously, in particular for more highly loaded gear components like synchromesh mechanisms. Porosity and frequently inadequate material properties of PM materials currently rule out PM for automobile gears that are subject to high loads. By increasing the density of the sintered gears, the mechanical properties are improved. New and optimized materials designed to allow the production of high-density PM gears by single sintering may change the situation in the future.
PowderMet 2009, plus the full technical calendar for Gear Technology's June 2009 issue.
Previews of manufacturing technology related to gears that will be on display at IMTS 2012.
There's a reason they call it catastrophic gear failure: For example, if the line goes down at a large aluminum rolling mill because a gear set goes bad, the cost can run up to a whopping $200,000 a week. Even in smaller operations, the numbers alone (not to mention all the other problems) can be a plant manager's worst nightmare.
the gear industry is awash in manufacturing technologies that promise to eliminate waste by producing gears in near-net shape, cut production and labor costs and permit gear designers greater freedom in materials. These methods can be broken down into the following categories: alternative ways to cut, alternative ways to form and new, exotic alternatives. Some are new, some are old and some are simply amazing.
Good timing leads to partnership between Process Equipment and Schafer Gear.
A trial test of the calibration procedures outlined in ISO 18653—Gears: Evaluation of Instruments for the Measurement of Individual Gears, shows that the results are reasonable, but a minor change to the uncertainty formula is recommended. Gear measuring machine calibration methods are reviewed. The benefits of using workpiece-like artifacts are discussed, and a procedure for implementing the standard in the workplace is presented. Problems with applying the standard to large gear measuring machines are considered and some recommendations offered.
A new inspection method has several advantages over traditional methods, especially for very large or very small gears.
Meeting the many challenges of large gear inspection.
Gear metrology is a revolving door of software packages and system upgrades. It has to be in order to keep up with the productivity and development processes of the machines on the manufacturing floor. Temperature compensation, faster inspection times and improved software packages are just a few of the advancements currently in play as companies prepare for new opportunities in areas like alternative energy, automotive and aerospace/defense.
Bringing new or improved products to market sooner has long been proven profitable for companies. One way to help shorten the time-to-market is to accelerate validation testing. That is, shorten the test time required to validate a new or improved product.
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.
Metrology is a vital component of gear manufacturing. Recent changes in this area, due in large part to the advent of computers, are highlighted in this article by comparison with more traditional methods.
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.
The advent of CNC technology as applied to gear shaping machines has, in the last 10 years, led to an astonishing improvement in both productivity and quality. As is usual when developments such as this take place, the technology of the machine tool suddenly jumps ahead of that of the cutting tool, and the machine is then capable of producing faster than the cutting tool can withstand.
I must admit that after thumbing through the pages of this relatively compact volume (113 pages, 8.5 x 11 format), I read its three chapters(theory of gearing, geometry and technology, and biographical history) from rear to front. It will become obvious later in this discussion why I encourage most gear engineers to adopt this same reading sequence!
Computer technology has touched all areas of our lives, impacting how we obtain airline tickets, purchase merchandise and receive medical advice. This transformation has had a vast influence on manufacturing as well, providing process improvements that lead to higher quality and lower costs. However, in the case of the gear industry, the critical process of tooth contact pattern development for spiral bevel gears remains relatively unchanged.
Gear pitting is one of the primary failure modes of automotive transmission gear sets. Over the past years, many alternatives have been intended to improve their gear surface durability. However, due to the nature of new process development, it takes a length of time and joint efforts between the development team and suppliers to investigate and verify each new approach.
Chairman Todd Praneis of Cotta Transmission describes the activities of AGMA's Enclosed Drives technical committee.
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.
Recently, I was approached by a colleague who is a manufacturer outside the gear industry...
The metal powder industry gathered in force this past June for PowderMet 2010, the 2010 International Conference on Powder Metallurgy and Particulate Materials.
Powder metallurgy (P/M) techniques have proven successful in displacing many components within the automobile drive train, such as: connecting rods, carriers, main bearing caps, etc. The reason for P/M’s success is its ability to offer the design engineer the required mechanical properties with reduced component cost.
How the latest techniques and software enable faster spiral bevel and hypoid design and development.
QuesTek Innovations LLC is applying its Materials by Design computational design technology to develop a new class of high-strength, secondary hardening gear steels that are optimized for high-temperature, low-pressure (i.e., vacuum) carburization. The new alloys offer three different levels of case hardness (with the ability to “dial-in” hardness profiles, including exceptionally high case hardness), and their high core strength, toughness and other properties offer the potential to reduce drivetrain weight or increase power density relative to incumbent alloys such as AISI 9310 or Pyrowear Alloy 53.
Conical involute gears (beveloids) are used in transmissions with intersecting or skewed axes and for backlash-free transmissions with parallel axes.
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.
Bore finishing system from Sunnen helps Cloyes Gear and Products achieve high accuracy, productivity and process capability.
The powder metal (P/M) process is making inroads in automotive transmission applications due to substantially lower costs of P/M-steel components for high-volume production, as compared to wrought or forged steel parts. Although P/M gears are increasingly used in powered hand tools, gear pumps and as accessory components in automotive transmissions, P/M-steel gears are currently in limited use in vehicle transmission applications. The primary objective of this project was to develop high-strength P/M-steel gears with bending fatigue, impact resistance and pitting fatigue performance equivalent to current wrought steel gears.
This article summarizes results of research programs on RCF strength of wrought steels and PM steels.
Despite economic uncertainty, the future looks promising for PM Gears.
This is part II of a two-part paper that presents the results of extensive test programs on the RCF strength of PM steels.
Increasingly gear designers and product engineers are capitalizing on the economic advantages of powder metallurgy (P/M) for new and existing gear applications. Powder metal gears are found in automobiles, outdoor power equipment transmissions and office machinery applications as well as power hand tools, appliances and medial components.
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.
Standards are unlike gears themselves: mundane, but complex, ubiquitous and absolutely vital. Standards are a lingua franca, providing a common language with reference points for evaluating product reliability and performance for manufacturers and users. The standards development process provides a scientific forum for discussion of product design, materials and applications, which can lead to product improvement. Standards can also be a powerful marketing tool for either penetrating new markets or protecting established ones.
This article summarizes the development of an improved titanium nitride (TiN) recoating process, which has, when compared to conventional recoat methods, demonstrated tool life increases of up to three times in performance testing of hobs and shaper cutters. This new coating process, called Super TiN, surpasses the performance of standard TiN recoating for machining gear components. Super TiN incorporates stripping, surface preparation, smooth coating techniques and polishing before and after recoating. The combination of these improvements to the recoating process is the key to its performance.
Long-time readers of these pages will know that I have always felt strongly about the subject of professional education. There's nothing more important for an individual's career development than keeping up with current technology. likewise, there's nothing more important that a company can do for itself and it employees than seeing to it they have the professional education they need. Giving people the educational tools they need to do their jobs is a necessary ingredient for success.
An engineer's responsibility for verifying a new design or product concept as manufacturable early in the development cycle is a tough challenge. What appears to work on a blueprint or in a three-dimensional CAD file on a computer screen many not work on the factory floor; and the downstream impact on the manufacturing process of an undetected design flaw can be enormous. Costs can run into the millions.
There are many different causes of gear noise, all of them theoretically preventable. Unfortunately, the prevention methods can be costly, both in equipment and manpower. If the design of the gear and its application are appropriate, in theory all that is necessary is to have a tight control on the process of producing the finished gear. In reality, there are many variables that can cause a process, no matter how well-controlled, to deteriorate, and thus cause errors, some of which will cause a gear to produce unwanted noise when put to use.
IMTS: It can be the best of times or the worst of times. The best because nowhere will you find more equipment, products and services for your business than at McCormick Place, Chicago, in September; the worst because finding your way around the show and around the city can be a hassle.
The heat treating of gears presents a difficult challenge to both the heat treater and the gear manufacturer. The number and variety of variables involved in the manufacturing process itself and the subsequent heat treating cycle create a complex matrix of factors which need to be controlled in order to produce a quality product. A heat treater specializing in gears or a gear manufacturer doing his own heat treating must have a clear understanding of these issues in order to deliver a quality product and make a profit at the same time. The situation also presents a number of areas that could benefit greatly from continued research and development.
Gear Expo '93 - another trade show, another plea to send people and/or equipment out of town, away from the office or plant. Another bid to spend time, money, and effort. Oh, please! Hasn't anybody heard that these are the "lean and mean" '90s?
Spur gear endurance tests were conducted to investigate the surface pitting fatigue life of noninvolute gears with low numbers of teeth and low contact ratios for the use in advanced application. The results were compared with those for a standard involute design with a low number of teeth. The gear pitch diameter was 8.89 cm (3.50 in.) with 12 teeth on both gear designs. Test conditions were an oil inlet temperature of 320 K (116 degrees F), a maximum Hertz stress of 1.49 GPa (216 ksi), and a speed of 10,000 rpm. The following results were obtained: The noninvolute gear had a surface pitting fatigue life approximately 1.6 times that of the standard involute gear of a similar design. The surface pitting fatigue life of the 3.43-pitch AISI 8620 noninvolute gear was approximately equal to the surface pitting fatigue life of an 8-pitch, 28-tooth AISI 9310 gear at the same load, but at a considerably higher maximum Hertz stress.
This past fall, I had the opportunity to travel to Japan, Korea, Taiwan, and Singapore to witness first-hand the status of the power transmission and machine tool industries in these areas. Points of interest included equipment, material handling, computerization, wage and tax structures, inventory controls, and workforce attitude.
Carburized and hardened gears have optimum load-carrying capability. There are many alternative ways to produce a hard case on the gear surface. Also, selective direct hardening has some advantages in its ability to be used in the production line, and it is claimed that performance results equivalent to a carburized gear can be obtained. This article examines the alternative ways of carburizing, nitriding, and selective direct hardening, considering equipment, comparative costs, and other factors. The objective must be to obtain the desired quality at the lowest cost.
Beginning with our next issue, some of the promised changes in format for Gear Technology will begin showing up in these pages. As part of our commitment to provide you with important information about the gear and gear products industry, we are expanding our coverage. In addition to continuing to publish some of the best results of gear research and development throughout the world, we will be adding special columns covering vital aspects of the gearing business.
Many potential problems are not apparent when using new induction heat treating systems. The operator has been trained properly, and setup parameters are already developed. Everything is fresh in one's mind. But as the equipment ages, personnel changes or new parts are required to be processed on the old equipment ages, personnel changes or new parts are required to b processed on the old equipment, important information can get lost in the shuffle.
8 Gear Technology advertisers will have booths at IMTS 92, the largest trade show in the Western Hemisphere. The show opens in Chicago on Sept. 9 and runs through the 17th. More than 800 companies from around the world will cover some 931,000 sq. ft. of exhibit space to show the latest manufacturing technology - everything from forming and fabrication products to environmental and plant safety equipment.
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.
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.
A research program, conducted in conjunction with a U.S. Army contract, has resulted in the development of manufacturing technology to produce a multi-metal composite gear/shaft representing a substantial weight savings compared to a solid steel component. Inertia welding is used to join a steel outer ring to a light-weight titanium alloy web and/or shaft through the use of a suitable interlayer material such as aluminum.
Most steel gear applications require appreciable loads to be applied that will result in high bending and compressive stresses. For the material (steel) to meet these performance criteria, the gear must be heat treated. Associated with this thermal processing is distortion. To control the distortion and achieve repeatable dimensional tolerances, the gear will be constrained during the quenching cycle of the heat treatment process. This type of fixture quenching is the function of gear quench pressing equipment.
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?
One of the key questions to be answered when exporting is how you are going to get your product to your customer. All the time, effort, and money you've spent to make a sale in the first place can be wasted if the shipment is late, damaged, or lost, or if delivery becomes an expensive bureaucratic nightmare for either you or the buyer.
Near-net gear forging today is producing longer life gears at significantly lower costs than traditional manufacturing techniques. Advances in forging equipment, controls and die-making capability have been combined to produce commercially viable near-net-shape gears in diameters up to 17" with minimum stock allowances. These forged gears require only minimal finishing to meet part tolerance specifications.
The goal of gear drive design is to transit power and motion with constant angular velocity. Current trends in gear drive design require greater load carrying capacity and increased service life in smaller, quieter, more efficient gearboxes. Generally, these goals are met by specifying more accurate gears. This, combined with the availability of user-friendly CNC gear grinding equipment, has increased the use of ground gears.
The tooth-by-tooth, submerged induction hardening process for gear tooth surface hardening has been successfully performed at David Brown for more than 30 years. That experience - backed up by in-depth research and development - has given David Brown engineers a much greater understanding of, and confidence in, the results obtainable from the process. Also, field experience and refinement of gear design and manufacturing procedures to accommodate the induction hardening process now ensure that gears so treated are of guaranteed quality.
Recent trends in gear cutting technology have left process engineers searching for direction about which combination of cutting tool material, coating, and process technology will afford the best quality at the lowest total cost. Applying the new technologies can have associated risks that may override the potential cost savings. The many interrelated variables to be considered and evaluated tend to cloud the issue and make hobbing process development more difficult.
An accurate and fast calculation method is developed to determine the value of a trigonometric function if the value of another trigonometric function is given. Some examples of conversion procedures for well-known functions in gear geometry are presented, with data for accuracy and computing time. For the development of such procedures the complete text of a computer program is included.
During the last decade, industrial gear manufacturers, particularly in Europe, began to require documentation of micropitting performance before approving a gear oil for use in their equipment. The development of micropitting resistant lubricants has been limited both by a lack of understanding of the mechanism by which certain lubricant chemistry promotes micropitting and by a lack of readily available testing for evaluation of the micropitting resistance of lubricants. This paper reports results of two types of testing: (1) the use of a roller disk machine to conduct small scale laboratory studies of the effects of individual additives and combinations of additives on micropitting and (2) a helical gear test used to study micropitting performance of formulated gear oils.
It used to be that gear manufacturers wanting to perform analytical gear inspection required at least three machines to do so: The lead measuring instrument, the tooth space comparator and the involute checking instrument. In the beginning, these machines were mechanically driven. Over the years, the manufacturers of analytical gear inspection equipment have combined these functions - and a host of others.
The major focus of the American Gear Manufacturers Association standards activity has been the accurate determination of a gearbox's ability to transmit a specified amount of power for a given amount of time. The need for a "level playing field" in the critical arena was one of the reasons the association was formed in the first place. Over the past 85 years, AGMA committees have spent countless hours "discussing" the best ways to calculate the rating of a gear set, often arguing vigorously over factors that varied the resulting answers by fractions of a percentage point. While all that "science" was being debated in test labs and conference rooms all over the country, out industry's customers were conducting their own experiments through the daily operation of gear-driven equipment of all types.
Traditionally, high-quality gears are cut to shape from forged blanks. Great accuracy can be obtained through shaving and grinding of tooth forms, enhancing the power capacity, life and quietness of geared power transmissions. In the 1950s, a process was developed for forging gears with teeth that requires little or no metal to be removed to achieve final geometry. The initial process development was undertaken in Germany for the manufacture of bevel gears for automobile differentials and was stimulated by the lack of available gear cutting equipment at that time. Later attention has turned to the forging of spur and helical gears, which are more difficult to form due to the radial disposition of their teeth compared with bevel gears. The main driver of these developments, in common with most component manufacturing, is cost. Forming gears rather than cutting them results in increased yield from raw material and also can increase productivity. Forging gears is therefore of greater advantage for large batch quantities, such as required by the automotive industry.
Romax Technology, the gearbox, bearing and driveline engineering specialist, has launched a new design software package that will increase speed, quality, creativity and innovation when designing gearboxes and drivelines. Called Concept, the new product delivers on the Romax vision of streamlining the end-to-end, planning-to-manufacture process with open, easy to use software solutions. It has been developed in close collaboration with engineers in the largest ground vehicle, wind energy and industrial equipment companies around the globe.
A large number of technologies aimed primarily at higher productivity were presented by exhibitors at the AMB, International Exhibition for Metal Working at the Stuttgart Trade Fair Centre in September. Following the successful 2010 show, AMB 2012 boasted further developments in energy and resource efficiency, higher productivity, life cycle performance, quality assurance and user-friendliness.
Gear tooth wear and micropitting are very difficult phenomena to predict analytically. The failure mode of micropitting is closely correlated to the lambda ratio. Micropitting can be the limiting design parameter for long-term durability. Also, the failure mode of micropitting can progress to wear or macropitting, and then go on to manifest more severe failure modes, such as bending. The results of a gearbox test and manufacturing process development program will be presented to evaluate super-finishing and its impact on micropitting.
Plastics as gear materials represent an interesting development for gearing because they offer high strength-to-weight ratios, ease of manufacture and excellent tribological properties (Refs. 1-7). In particular, there is a sound prospect that plastic gears can be applied for power transmission of up to 10 kW (Ref. 6).
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.
Thousands of gear industry professionals will converge October 24-27 in Nashville, TN, for Gear Expo 99, the industry's biennial collection of the latest in gear manufacturing technology. With nearly 50,000 square feet of exhibit space sold more than two months in advance of the show, this year's Gear Expo will offer visitors more opportunity for supplier comparison than ever before. As of July 20, 166 suppliers of equipment, tooling, services and precision gear products were scheduled to participate, with as many as 20 additional booths yet to be sold, according to AGMA vice president and Gear Expo show manager Kurt Medert. The largest previous Gear Expo was held in 1997 in Detroit, with 43,100 square feet of exhibit space and 161 exhibitors.
A fundamental characteristic of the gear industry is that it is capital intensive. In the last decade, the gear manufacturing industry has been undergoing an intense drive toward improving and modernizing its capital equipment base. The Department of Commerce reports that annual sales of gear cutting equipment have increased nearly 60% since 1990. While this effort has paid off in increased competitiveness for the American gear industry, it is important to remember that there is another capital crucial to manufacturing success - "human capital."
Several articles have appeared in this publication in recent years dealing with the principles and ways in which the inspection of gears can be carried out, but these have dealt chiefly with spur, helical and bevel gearing, whereas worm gearing, while sharing certain common features, also requires an emphasis in certain areas that cause it to stand apart. For example, while worm gears transmit motion between nonparallel shafts, as do bevel and hypoid gears, they usually incorporate much higher ratios and are used in applications for which bevel would not be considered, including drives for rotary and indexing tables in machine tools, where close tolerance of positioning and backlash elimination are critical, and in situations where accuracy of pitch and profile are necessary for uniform transmission at speed, such as elevators, turbine governor drives and speed increasers, where worm gears can operate at up to 24,000 rpm.
In 1961 I presented a paper, "Calculating Conjugate Helical Forms," at the semi-annual meeting of the American Gear Manufacturers Association (AGMA). Since that time, thousands of hobs, shaper cutters and other meshing parts have been designed on the basis of the equations presented in that paper. This article presents the math of that paper without the formality of its development and goes on to discuss its practical application.
Gleason Corporation has announced that agreement has been reached on all terms to acquire for approximately $36 million in cash the Hermann Pfauter Group, including, among other operations, Hermann Pfauter GmbH & Co., a privately held leading producer of gear equipment based in Ludwigsburg, Germany; its 76% interest in Pfauter-Maad Cutting Tools, a leading cutting tool manufacturer basked in Loves Park, IL; and Pfauter-Maag management's 24% ownership interest in that company. The acquisition includes all assets and liabilities, including the assumption of approximately $56 million in bank debt.
The American Gear Manufacturers Association (AGMA) is accredited by the American National Standards Institute (ANSI) to write all U.S. standards on gearing. However, in response to the growing interest in a global marketplace, AGMA became involved with the International Standards Organization (ISO) several years ago, first as an observer in the late 1970s and then as a participant, starting in the early 1980s. In 1993, AGMA became Secretariat (or administrator) for Technical Committee 60 of ISO, which administers ISO gear standards development.
ISO 6336 Calculation of Load Capacity of Spur and Helical Gears was published in 1997 after 50 years of effort by an international committee of experts whose work spanned three generations of gear technology development. It was a difficult compromise between the existing national standards to get a single standard published which will be the basis for future work. Many of the compromises added complication to the 1987 edition of DIN 3990, which was the basic document.
Although the cultures and areas of expertise of Solomon and Sun Tzu are worlds apart, the two offer similar opinions on the importance of seizing the moment. Their ancient wisdom may have increasing relevance to modern manufacturers in a global economy, particularly those contemplating whether now is the time to invest in capital equipment.
The efficient and reliable transmission of mechanical power continues, as always, to be a central area of concern and study in mechanical engineering. The transmission of power involves the interaction of forces which are transmitted by specially developed components. These components must, in turn, withstand the complex and powerful stresses developed by the forces involved. Gear teeth transmit loads through a complex process of positive sliding, rolling and negative sliding of the contacting surfaces. This contact is responsible for both the development of bending stresses at the root of the gear teeth and the contact stresses a the contacting flanks.
The Gear Research Laboratory of the University of Illinois at Chicago is home to a unique tribute to gear pioneers from around the world, the Gallery of Fame. The gallery is the brainchild of the laboratory director, Professor Faydor L. Litvin. The Gallery was begun in 1994 an dis a photographic tribute to those gear company founders, inventors and researchers who devoted their careers to the study and development of gears.
Air compressors are a good example of industrial machinery with components that rotate at very high speeds, up to 80,000 rpm. They are subject to very high rotational forces and often variable loads. Strong, high-precision gears for the power transmission trains that drive the impellers are critical components of machinery operating under such conditions.
In 1993, M & M Precision Systems was awarded a three-year, partial grant from the Advanced Technology Program of the Department of Commerce's National Institute of Standards and Technology (NIST). Working with Pennsylvania State University, M&M embarked on a technology development project to advance gear measurement capabilities to levels of accuracy never before achieved.
In the August 2008 issue of Gear Technology, we ran a story (“Gearbox Speed Reducer Helps Fan Technology for ‘Greener” Jet Fuel Efficiency’) on the then ongoing, extremely challenging and protracted development of Pratt & Whitney’s geared turbofan (GTF) jet engine.
This paper introduces new process developments in low-pressure carburizing and carbonitriding using either high-pressure gas quenching or interrupted gas quenching.
The United States’ long-held dream of energy independence—as in cheap, clean, free of overseas extortion and renewable energy—could very well be realized in part by the country-wide development of wind turbines...
Material losses and long production times are two areas of conventional spur and helical gear manufacturing in which improvements can be made. Metalforming processes have been considered for manufacturing spur and helical gears, but these are costly due to the development times necessary for each new part design. Through a project funded by the U.S. Army Tank - Automotive Command, Battelle's Columbus Division has developed a technique for designing spur and helical gear forging and extrusion dies using computer aided techniques.
It may not be widely recognized that most of the inspection data supplied by inspection equipment, following the practices of AGMA Standard 2015 and similar standards, are not of elemental accuracy deviations but of some form of composite deviations. This paper demonstrates the validity of this “composite” label by first defining the nature of a true elemental deviation and then, by referring to earlier literature, demonstrating how the common inspection practices for involute, lead (on helical gears), pitch, and, in some cases, total accumulated pitch, constitute composite measurements.
In the field of large power transmission gear units for heavy machine industry, the following two development trends have been highly influential: use of case hardened gears and a branching of the power flow through two or more ways.
This paper describes the research and development of the first production gearbox with asymmetric tooth profiles for the TV7-117S turboprop engine. The paper also presents numerical design data related to development of this gearbox.
The 130SV shaving machine from Gleason is the newest of the company's Genesis family of gear production equipment.
As the automotive industry continues to reinvent itself, new transmission technologies are at the forefront of this effort, and there is a whirlwind of new developments being detailed at the German Car Training Institute’s Automotive Transmissions and Drive Trains Symposium North America.
This study quantified the performance of a new alloy and has provided guidance for the design and development of next-generation gear steels.
Synopsis on the latest developments at several gear design software developers.
With all the work in transmission development these days, the demand for automobile transmission gears should remain strong for several years, but suppliers will have to be as flexible as possible to keep up with the changes.
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.
"Gears of Gold" and "Process Equipment's Virtual ND430."
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.
In the past, the coffee breaks and dinner events at Sigma Pool’s gear seminars have often triggered future process development and product improvements. This was still the case during the 2009 installment where customers and suppliers talked shop inside and outside the banquet hall on the new market and technology challenges currently facing the gear industry.
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.
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.
Industrial gear standards have been used to support reliability through the specification of requirements for design, manufacturing and verification. The consensus development of an international wind turbine gearbox standard is an example where gear products can be used in reliable mechanical systems today. This has been achieved through progressive changes in gear technology, gear design methods and the continual development and refinement of gearbox standards.
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.
Much information has been written on gear inspection, analytical. functional. semiautomatic and automatic. In most cases, the charts, (if you are lucky enough to have recording equipment) have been explained.
Since the design of involute splines and their manufacture requires considerable knowledge, not only of the basic properties of the involute profile, but also of various other elements which affect the spline fit and the sometimes complex principles underlying manufacturing and checking equipment, the question is frequently raised as to why the involute profile is given preference in designing splines over the seemingly simpler straight sided tooth profile.
Hobs, broaches, shaper cutters, shaver cutters, milling cutters, and bevel cutters used in the manufacture of gears are commonly made of high speed steel. These specialized gear cutting tools often require properties, such as toughness or manufacturability, that are difficult to achieve with carbide, despite the developments in carbide cutting tools for end mills, milling cutters, and tool inserts.
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.
In the hypercompetitive race to increase automobile efficiency, Metaldyne has been developing its balance shaft module line with Victrex PEEK polymer in place of metal gears. The collaborative product development resulted in significant reductions in inertia, weight and power consumption, as well as improvement in noise, vibration and harshness (NVH) performance.
Investment in Gleason GMM Series inspection equipment helps drive Milwaukee Gear's expansion into profitable new markets around the world—all hungry for high-precision custom gears and gear drives.
Noisy gear trains have been a common problem for gear designers for a long time. With the demands for smaller gear boxes transmitting more power at higher rpms and incumbent demands for greater efficiency, gear engineers are always searching for new ways to reduce vibration and limit noise without increasing costs.
The last decade has been a period of far-reaching change for the metal working industry. The effect of higher lubricant costs, technical advances in machine design and increasing competition are making it essential that manufacturers of gears pay more attention to testing, selecting and controlling cutting fluid systems. Lubricant costs are not a large percentage of the process cost relative to items such as raw materials, equipment and labor, and this small relative cost has tended to reduce the economic incentive to evaluate and to change cutting fluids.
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.
As Gear Technology moves toward its third anniversary, we feel that we have reached a point in our development where it is time to pause, reflect on our accomplishments and plan for the future.
Gear manufacturing schedules that provide both quality and economy are dependent on efficient quality control techniques with reliable measuring equipment. Given the multitude of possible gear deviations, which can be found only by systematic and detailed measuring of the gear teeth, adequate quality control systems are needed. This is especially true for large gears, on which remachining or rejected workpieces create very high costs. First, observation of the gears allows adjustment of the settings on the equipment right at the beginning of the process and helps to avoid unproductive working cycles. Second, the knowledge of deviations produced on the workpiece helps disclose chance inadequacies on the production side: e.g., faults in the machines and tools used, and provides an opportunity to remedy them.
It is with great anticipation that we move closer to AGMA's Fall Technical Conference and Gear Expo '87, which is being held on Oct. 4-6 in Cincinnati, OH. This bold undertaking by both AGMA and the exhibitors in the Expo's 160 booths is an attempt to make a major change in the industry's approach to the exposition of gear manufacturing equipment. By combining the Expo with the Fall Technical Conference, those involved in gear manufacturing will have the opportunity to review the latest equipment, trends, and most innovative ideas, while keeping up with the newest technology in the industry.
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.
Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9210 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temperature of 320 K (116 degree F), an outlet oil temperature of 350 K (170 degree F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.
Primitive gears were known and used well over 2,000 years ago, and gears have taken their place as one of the basic machine mechanisms; yet, our knowledge and understanding of gearing principles is by no means complete. We see the development of faster and more reliable gear quality assessment and new, more productive manufacture of gears in higher materials hardness states. We have also seen improvement in gear applications and design, lubricants, coolants, finishes and noise and vibration control. All these advances push development in the direction of smaller, more compact applications, better material utilization and improved quietness, smoothness of operation and gear life. At the same time, we try to improve manufacturing cost-effectiveness, making use of highly repetitive and efficient gear manufacturing methods.
The concept of "transmission error" is relatively new and stems from research work in the late 1950s by Gregory, Harris and Munro,(1) together with the need to check the accuracy of gear cutting machines. The corresponding commercial "single flank" testing equipment became available in the 1960s, but it was not until about ten years ago that it became generally used, and only recently has it been possible to test reliably at full load and full speed.
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.
A change has taken place within the industry that is going to have an enormous effect on the marketing, sales, and purchasing of gear manufacturing and related equipment. This change was the American Gear Manufacturers' Association, first biennial combination technical conference and machine tool minishow.
Curvic Couplings were first introduced in 1942 to meet the need for permanent couplings and releasing couplings (clutches), requiring extreme accuracy and maximum load carrying capacity, together with a fast rate of production. The development of the Curvic Coupling stems directly from the manufacture of Zerol and spiral bevel gears since it is made on basically similar machines and also uses similar production methods. The Curvic Coupling can therefore lay claim to the same production advantages and high precision associated with bevel gears.
AGMA Flexible Couplings committee chairman Glenn C. Pokrandt gives an update about standards and other documents under development.
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.
Bradley University and Winzeler Gear collaborate on the design and development of an urban light vehicle.
Minimizing gear losses caused by churning, windage and mesh friction is important if plant operating costs and environmental impact are to be minimized. This paper concentrates on mesh friction losses and associated scuffing risk. It describes the preliminary results from using a validated, 3-D Finite Element Analysis (FEA) and Tooth Contact Analysis (TCA) program to optimize cylindrical gears for low friction losses without compromising transmission error (TE), noise and power density. Some case studies and generic procedures for minimizing losses are presented. Future development and further validation work is discussed.
This article describes some of the most important tests for prototypes conducted at Winergy AG during the product development process. It will demonstrate that the measurement results on the test rig for load distribution are in accordance with the turbine measurements.
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.
Worm gearing is of great antiquity, going back about 2100 years to Archimedes, who is generally acknowledged as its inventor. Archimedes' concept used an Archimedial spiral to rotate a toothed wheel. Development of the worm gearing principle progressed along conventional lines until about 500 years ago when Leonardo DaVinci evolved the double enveloping gear concept.
What was once recognized as the unique genius of America is now slipping away from us and, in many areas, is now seen as a "second rate" capability. Unless action is taken now, this country is in real danger of being unable to regain its supremacy in technological development and economic vigor. First Americans must understand the serious implications of the problem; and second, we must dedicate ourselves to national and local actions that will ensure a greater scientific and technological literacy in America.
Faithful Addendum readers are accustomed to finding upbeat, whimsical and oddball stories about gears in this space. What follows is not about gears, exactly. Rather, it is, as opposed to the usual bleak news about America losing its manufacturing mojo—a look at a positive, hopeful development in that regard.
The Forest City Gear booth at Gear Expo featured a wide variety of gears utilized in medical equipment, Indy cars, fishing reels, even the recently launched Mars Rover. Scattered among Forest City’s products in Cincinnati were some unique gear sculptures created by an artist that finds more inspiration from the pages of industrial magazines than art galleries.
Traditional methods of manufacturing precision gears usually employ either hobbing or shaper cutting. Both of these processes rely upon generating the conjugate tooth form by moving the work-piece in a precise relation to the tool. Recently, attention has been given to forming gear teeth in a single step. Advantages to such a process include reduced production time, material savings, and improved performance characteristics. Drawbacks include complicated tool designs, non-uniformity of gears produced throughout the life of the tooling, and lengthy development times.
News Items About PM
1 Gear Applications Discussed at Euro PM 2011 (December 6, 2011)
Gear applications have emerged as an important target for the PM structural parts sector and several of the leading PM groups have develo... Read News
2 PMAEF Issues Awards to Metalforming Industry (February 22, 2011)
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3 NTMA & PMA Support Currency Legislation (October 13, 2011)
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4 PMA Business Report for December Optimistic (December 15, 2010)
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5 Outstanding PM Parts Awarded (July 24, 2008)
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6 NTMA & PMA Issue Statement on Small Business Lending (May 25, 2010)
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7 PMA Anticipates Continued Improvement (February 16, 2011)
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8 Abstracts for PM2010 World Congress Now Available (June 16, 2010)
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9 PMA Elects New Leaders (January 26, 2011)
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10 PMA Predicts Business to Improve (February 20, 2012)
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11 PMA Reports Business Conditions Steady in January 2008 (February 14, 2008)
According to the January 2008 Precision Metalforming Association (PMA) Business Conditions Report, metalforming companies expect business... Read News
12 PMA Introduce Series of Programs Highlighting Servo Press Technology (August 9, 2012)
The Precision Metalforming Association's (PMA) flagship publication, MetalForming magazine, announces a series of new technical progr... Read News
13 PMA Business Conditions Improve (August 20, 2012)
According to the August 2012 Precision Metalforming Association (PMA) Business Conditions Report, metalforming companies expect a slight ... Read News
14 FMS Wins PM Award (July 26, 2012)
FMS Corporation, Minneapolis, Minnesota, won the grand prize in the lawn & garden/off-highway category for a PM steel gear race used ... Read News
15 PMA Releases Business Conditions Report (May 21, 2012)
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16 Process Equipment Announces Partnerships (August 30, 2007)
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17 Northstar Aerospace Receives Contract for New Drive System Development (August 30, 2007)
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18 Sensor Development’s Latest Model Measures Small Reaction Torque Level (August 6, 2007)
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19 Schafer Gear Adds New Grinding Equipment (May 24, 2007)
Schafer Gear Works invested in new production equipment, including new gear grinding machines in the company's South Bend, IN, and Ro... Read News
20 Philadelphia Gear Offers Two Versions of Continuous Oil Rescue Equipment (March 5, 2007)
Philadelphia Gear Corp. announced the availability of two versions of the company's proprietary CORE Continuous Oil Rescue Equipment.... Read News
21 Process Equipment Sold, President Retires (April 24, 2005)
Larry Ewald announced his retirement after 27 years at Process Equipment Co. In 1978, he succeeded the company's founder, Emmert Stud... Read News
22 Donner + Pfister Introduces New Measuring Equipment (January 19, 2005)
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23 United Gear Installs New Inspection Equipment (December 16, 2003)
United Gear & Inspection has installed a new M&M Precision gear inspection machine to double its manufacturing capacity. According to ... Read News
24 Recent Developments at Ikona Gear (February 21, 2005)
Ikona Gear has entered into a developmental agreement with StarRotor Corp. to provide patented Ikona technology for the third generation ... Read News
25 Cowley Hired as Sales Manager of Process Equipment (April 12, 2005)
Bruce Cowley was hired as sales manager for the metrology systems division of Process Equipment Co. According to the company's p... Read News
26 GM, BMW and DaimlerChrysler Announce $1 Billion Hybrid Transmission Development Program (April 15, 2006)
A research alliance consisting of GM, BMW and DaimlerChrysler plans to invest more than $1 billion to develop a new hybrid transmission t... Read News
27 Process Equipment Sold, President Retires (April 19, 2005)
Larry Ewald announced his retirement after 27 years at Process Equipment Co. In 1978, he succeeded the companys founder, Emmert Stu... Read News
28 Wall Colmonoy Appoints Business Development Manager (April 17, 2006)
Morris Warino was appointed business development manager for Wall Colmonoy Corp. of Oklahoma City, OK. According to the companys... Read News
29 Romax Appoints Business Development Manager for Hybrid Technology (June 15, 2010)
Romax Technology recently recruited a new business development manager to manage Romax's hybrid and electric vehicle consultancy.&nbs... Read News
30 Hole Specialists Add Equipment Before Expansion Project (December 16, 2011)
Everything is bigger in Texas, and come February 2012, Tomball-based Hole Specialists will be bigger after it moves into a 25,800 sq. ft.... Read News
31 PMA to Host Inaugural Women in Manufacturing Symposium (September 16, 2011)
More than 150 women executives, managers and supervisors will gather in Cleveland, Ohio, on October 25-26, 2011 for the first annual Wome... Read News
32 PTG Appoints Group Business Development Director (October 2, 2012)
Precision Technologies Group (PTG), the U.K.-based specialists in high-precision machine tool and component design, build and supply, hav... Read News
33 The Manufacturing Institute Partners with PMPA on Machine Training Program (October 11, 2012)
The Manufacturing Institute has partnered with the Precision Machined Products Association, Right Skills Now, a fast-track machining trai... Read News
34 Mazak to Exhibit at PMTS 2013 (February 18, 2013)
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35 IMS Research Analyzes Geared Product Shipments (December 27, 2012)
Shipments of precision geared products (gearboxes and geared motors with backlash ratings of less than 20 arcminutes) were nearly 80 perc... Read News
36 Minera Re-Sizes Metso's Equipment for Mining Project (June 22, 2011)
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37 Nevada Heat Treating Invests in New Equipment (April 4, 2011)
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38 PM Association Names President (April 2, 2009)
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39 Forest City Gear Invests in Capital Equipment (February 12, 2009)
Forest City Gear has announced it has invested more than $6 million in the purchase of new capital equipment during the last 18 months. T... Read News
40 FMS Awarded for Outstanding PM Part (August 19, 2009)
The Metal Powder Industries Federation (MPIF) presented FMS Corporation with the Outstanding Powder Metallurgy Parts Grand Prize in the l... Read News
41 Halifax Rack and Screw Invests in New Equipment (August 25, 2009)
The Cincinnati North America distribution center for Halifax Rack and Screw Cutting Company of Cincinnati, OH and Brighouse, England has... Read News
42 Romax Improves Driveline Design and Development (May 15, 2013)
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43 PM Touches Your Life DVD Released (January 27, 2010)
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44 AMSC Partners with Shenyang Blower Works for Turbine Development (November 24, 2008)
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