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(SPONSORED CONTENT)Low Pressure Vacuum Carburizing of Gears
Solar Atmospheres provides low pressure vacuum carburizing (LPVC) that significantly increases the surface hardness/strength of steel parts for improved friction and wear. Performing LPVC in a vacuum furnace eliminates oxygen and prevents IGO (intergranular oxidation) that is inherent in atmospheric carburizing, resulting in clean parts with less distortion reducing post process finishing operations, and costs. Article Courtesy of Solar Atmospheres
Many techniques have been developed over the years to control heat treatment distortion, including the use of different quenching medias, optimization of heat treatment cycles, altering the material chemical composition and even press quenching. Now, learn about Quenching in the 4th Dimension! SECO/VACUUM's Tom Hart presented a webinar about 4D Quenching technology, a safe and simple hands-off heat treatment process, minus the challenges of press quenching. Article Courtesy of Seco/Vacuum
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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.
Heat treating is one of the most critical operations in the manufacture of quality gears. Everything can be done to perfection, but if the heat treating isnâ€™t right, all of your hard work and efforts are wasted. We know how important it is for gear manufacturers to find the right heat treating service provider. Thatâ€™s why weâ€™ve compiled this Heat Treat Resource Guide -- the only directory of heat treat service providers thatâ€™s specific to the gear industry. The companies listed here are all interested in working with gear manufacturers, and many of them have specialties and capabilities that are uniquely suited to the types of products you manufacture.
Heat Treating - The evil twin of the gear processing family. Heat treating and post-heat treating corrective processes can run up to 50% or more of the total gear manufacturing cost, so it's easy to see why, in these days when "lean and mean" production is the rage, and every part of the manufacturing process is under intense scrutiny, some of the harshest light falls on heat treating.
The manufacturing process to produce a gear essentially consist of: material selection, blank preshaping, tooth shaping, heat treatment, and final shaping. Only by carefully integrating of the various operations into a complete manufacturing system can an optimum gear be obtained. The final application of the gear will determine what strength characteristics will be required which subsequently determine the material and heat treatments.
Audits of the heat treating department are a vital part of any good quality program - either as part of a self-assessment or ISO program for a captive shop or - of equal importance - as part of an evaluation of the capabilities of a commercial heat treat supplier. In either case, the audit process needs to be formal in nature and follow specific guidelines.
Suppliers are working hard to make sure their heat treating equipment is controllable, repeatable and efficient, and manufacturers continue to incorporate technology that gives heat treaters and their customers more information about what's going on inside the magic box.
When sending gears to be heat treated, manufacturers can end up unwittingly making mistakes that slow down turnaround time. We talked to some heat treaters to get their best advice on how you can help them help you.
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.
In this special section, our editors have gathered recent news and information related to the heat treatment of gears. Here youâ€™ll find a comprehensive assortment of news and upcoming events that will help you understand the various heat treatment processes available for gears and choose the best option for your projects, whether you heat treat in-house or send your gears to a commercial heat treating provider.
Precision components (industrial bearing races and automotive gears) can distort during heat treatment due to effects of free or unconstrained oil quenching. However, press quenching can be used to minimize these effects. This quenching method achieves the relatively stringent geometrical requirements stipulated by industrial manufacturing specifications. As performed on a wide variety of steel alloys, this specialized quenching technique is presented here, along with a case study showing the effects of prior thermal history on the distortion that is generated during press quenching.
The selection of the heat treat process and the congruent material required for high performance gears can become very involved.
The following article highlights some of the new heat treat products, technologies and industry news articles that have come across our desks.
Graded hardening technology has proven over the years to yield very good results when used in the heat treating of carburized gears. It is especially advantageous for smaller companies, subject to higher competitive pressures. Unfortunately, despite the fact that graded hardening is a very well-known method, its use has been limited. We strongly recommend this technology to all of those who need to produce gears with high metallurgical quality.
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.
This paper presents how low pressure carburizing and high pressure gas quenching processes are successfully applied on internal ring gears for a six-speed automatic transmission. The specific challenge in the heat treat process was to reduce distortion in such a way that subsequent machining operations are entirely eliminated.
Heat treating is a critical operation in gear manufacturing. It can make or break the quality of your final product. Yet it is one that frequently gear manufacturers outsource to someone else. Then the crucial question becomes, how do you know you're getting the right heat treater? How can you guarantee your end product when you have turned over this important process to someone else?
The induction hardening and tempering of gears and critical components is traditionally a hot subject in heat treating. In recent years, gear manufacturers have increased their knowledge in this technology for quality gears.
An overview of the latest technology and trends in heat treating.
Gear Technology's directory of heat treating suppliers for the gear industry.
The large gears found in mining, steel, construction, off-road, marine and energy applicationsâ€”massive and robust in natureâ€”need to tackle the greatest production demands. This, in turn, means that a special emphasis must be put on the heat treating methods used to increase the wear resistance and strength properties of gears this size.
The following article highlights some of the recent heat treat products, technologies and industry news articles for gear manufacturing.
The latest heat treating news from March/April 2005
News from around the world about heat treating.
Gear designs are evolving at an ever accelerating rate, and gear manufacturers need to better understand how the choice of materials and heat treating methods can optimize mechanical properties, balance overall cost and extend service life.
Precise heat treatment plays an essential role in the production of quality carburized gears. Seemingly minor changes in the heat treating process can have significant effects on the quality, expense and production time of a gear, as we will demonstrate using a case study from one of our customer's gears.
In recent years, there has been significant interest in expanding the use of induction hardening in gear manufacturing operations. Over the past several years, many of the limits to induction hardening have shrunk, thanks to recent advances in technology, materials and processing techniques.
Map and listings of the ASM Heat Treat Expo 2019.
The latest technology on display in Columbus, OH. October 24-26.
Heat treating is a vital step in the gear making processâ€”thatâ€™s a given. But how that step is taken can happen in a number of ways.
The future gives the gear market plenty to think about in areas like automation, additive manufacturing and machine learning.
Your guide to the booths at ASM's Heat Treat 2013 show.
Acetylene with DMF solvent enables benefits of low-pressure vacuum carburizing.
New innovations in the management of hear treating parts washers and yielding powerful, unexpected benefits. Simply, cost effective shop floor practices are being combined in new ways to deliver big quality improvements and significant help to the bottom line. Employing these steps early in the process can dramatically cut waste hauling expenses and greatly reduce environmental liabilities while continuously producing cleaner parts.
The performance of metal surfaces can be dramatically enhanced by the thermal process of rapid surface melting and re-solidification (RMRS). When the surface of a metal part (for instance, a gear) is melted and re-solidified in less than one thousandth of a second, the resulting changes in the material can lead to: Increased wear and corrosion resistance, Improved surface finish and appearance, Enhanced surface uniformity and purity, and Sealing of surface cracks and pores.
The heat treatment processing of powder metal (PM) materials like Astaloy requires four steps -- de-waxing, HT sintering, carburizing and surface hardening -- which are usually achieved in dedicated, atmospheric furnaces for sintering and heat treat, respectively, leading to intermediate handling operations and repeated heating and cooling cycles. This paper presents the concept of the multi-purpose batch vacuum furnace, one that is able to realize all of these steps in one unique cycle. The multiple benefits brought by this technology are summarized here, the main goal being to use this technology to manufacture high-load transmission gears in PM materials.
Furnace Suppliers and Heat Treaters Remain Busy During Tough Times
Before the optimum mechanical properties can be selected, the working stress must be determined, based on recommended allowable stresses.
Bob McCulley of Comprehensive Heat Treat Specialists describes how even the most energy intensive industrial processes can be made "green."
What quality and performance characteristics should you look for?
As the way things are manufactured continues to evolve, manufacturing trade shows are keeping pace with that evolution. A perfect example of that can be found at this yearâ€™s biennial Heat Treat 2019 (Oct. 15â€“Oct. 17, COBO Center, Detroit)
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.
A widespread weakness of gear drawings is the requirements called out for carburize heat treating operations. The use of heat treating specifications is a recommended solution to this problem. First of all, these specifications guide the designer to a proper callout. Secondly, they insure that certain metallurgical characteristics, and even to some extent processing, will be obtained to provide the required qualities in the hardened gear. A suggested structure of carburizing specifications is give.
Don't miss these exhibitors co-located with Gear Expo.
Heat treat suppliers look to the gear industry and the upcoming combined Gear Expo/Heat Treat 2013 for new business.
Induction hardening is a heat treating technique that can be used to selectively harden portions of a gear, such as the flanks, roots and tips of teeth, providing improved hardness, wear resistance, and contact fatigue strength without affecting the metallurgy of the core and other parts of the component that donâ€™t require change. This article provides an overview of the process and special considerations for heat treating gears. Part I covers gear materials, desired microsctructure, coil design and tooth-by-tooth induction hardening.
Single Piece Flow Streamlines Production for High-Volume Gear Manufacturers.
The proper control of distortion after thermal treatment of powertrain components in the automotive industry is an important measure in ensuring high-quality parts and minimizing subsequent hard machining processes in order to reduce overall production costs.
The author conducts a simple experiment to verify his anecdotal knowledge about chamfering hard vs soft parts.
Map and listings to the ASM Heat Treating Society Conference and Exposition, which is co-located with this year's Gear Expo.
Co-located ASM and AGMA shows are a hot ticket.
This issue, GT Extras brings you "Heat Treat and Induction Hardening of Industrial Gears," a treasure trove of heat treating related technical articles and a call for help in preparation for AGMA's 100th anniversary.
Open any heat treating journal today and youâ€™re certain to find multiple references (articles, technical papers and/or advertisements) promoting low-pressure carburizing (LPC). The uninformed might breeze by these references thinking itâ€™s the next flash-in-the-pan, but unlike in the past, this time the process has legs.
Compared to non-heat-treated components, case-carburized gears are characterized by a modified strength profile in the case-hardened layer. The design of case-carburized gears is based on defined allowable stress numbers. These allowable stress numbers are valid only for a defined "optimum" case depth. Adequate heat treatment and optimum case depth guarantee maximum strength of tooth flank and tooth root.
Carburized gears have higher strengths and longer lives compared with induction-hardened or quench-tempered gears. But in big module gears, carburizing heat-treatment becomes time-consuming and expensive and sometimes cannot achieve good hardness due to the big mass-effect. Also, it is not easy to reduce distortion of gears during heat treatment.
The October 2011 issue of Gear Technology featured the article â€śLow-Distortion Heat Treatment of Transmission Components,â€ť which covered the combination of low-pressure carburizing and high pressure gas quenching in an automotive environment. Here, heat treating expert Dan Herring explains why oil quenching is an appropriate choice for many applications.
Austempering heat treatments (austenitizing followed by rapid cooling to the tempering temperature) have been applied to nodular irons on an experimental basis for a number of years, but commercial interest in the process has only recently come to the surface.
High demands for cost-effectiveness and improved product quality can be achieved via a new low pressure carburizing process with high pressure gas quenching. Up to 50% of the heat treatment time can be saved. Furthermore, the distortion of the gear parts could be reduced because of gas quenching, and grinding costs could be saved. This article gives an overview of the principles of the process technology and the required furnace technology. Also, some examples of practical applications are presented.
So, you've been assigned the task to buy an induction heating system for heat treating: It's an intimidating, but by no means impossible, assignment. With the help of the information in this article, you could be able to develop common ground with your supplier and have the tools to work with him or her to get the right machine for your jobs.
Quality gear manufacturing depends on controlled tolerances and geometry. As a result, ferritic nitrocarburizing has become the heat treat process of choice for many gear manufacturers. The primary reasons for this are: 1. The process is performed at low temperatures, i.e. less than critical. 2. the quench methods increase fatigue strength by up to 125% without distorting. Ferritic nitrocarburizing is used in place of carburizing with conventional and induction hardening. 3. It establishes gradient base hardnesses, i.e. eliminates eggshell on TiN, TiAIN, CrC, etc. In addition, the process can also be applied to hobs, broaches, drills, and other cutting tools.
Induction hardening is widely used in both the automotive and aerospace gear industries to minimize heat treat distortion and obtain favorable compressive residual stresses for improved fatigue performance. The heating process during induction hardening has a significant effect on the quality of the heat-treated parts. However, the quenching process often receives less attention even though it is equally important.
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.
Gear making and heat treating pair together like a fine cabernet and filet mignon. Now for the first time, the two industries are embracing this symbiotic relationship by co-locating their industry events this fall in Indianapolis. ASM Internationalâ€™s 2009 Heat Treating Society Conference and Exposition and Gear Technologyâ€™s favorite trade show, Gear Expo, are teaming up September 14â€“17 at the Indiana Convention Center in Indianapolis.
For many years chromium has been a popular alloy for heat treatable steels because of its contribution to hardenability more than offsets its costs. As a consequence, it is specified in such high-tonnage steel grades as the 5100, 4100, and 8600 series; and, as a result, about 15% of the annual U.S. consumption of chromium is used in constructional alloy steels.
When it comes to setting the standard for gear making, the auto industry often sets the pace. Thus when automakers went to grinding after hardening to assure precision, so did the machine shops that specialize in gearing. But in custom manufacturing of gears in small piece counts, post-heat treat grinding can grind away profits too.
The U.S. heat treat industry is in the middle of a labor shortage. Here's a look at what companies in the industry are doing about it.
Ausforming, the plastic deformation of heat treatment steels in their metastable, austentic condition, was shown several decades ago to lead to quenched and tempered steels that were harder, tougher and more durable under fatigue-type loading than conventionally heat-treated steels. To circumvent the large forces required to ausform entire components such as gears, cams and bearings, the ausforming process imparts added mechanical strength and durability only to those contact surfaces that are critically loaded. The ausrolling process, as utilized for finishing the loaded surfaces of machine elements, imparts high quality surface texture and geometry control. The near-net-shape geometry and surface topography of the machine elements must be controlled to be compatible with the network dimensional finish and the rolling die design requirements (Ref. 1).
A carburized alloy steel gear has the greatest load-carrying capacity, but only if it is heat treated properly. For high quality carburizing, the case depth, case microstructure, and case hardness must be controlled carefully.
Heat treating and quenching are arguably the most critical operations in the manufacture of gears. This article examines causes of distortion in heat treating and quenching.
What gear material is suitable for high-temperature (350 â€“ 550 degree C), high-vacuum, clean-environment use?
New technology from Eldec/EMAG helps control the induction hardening process.
Environmentally friendly, highly efficient and lasting a product's lifetime. With characteristics like this, Pulsed-Plasma Diffusion (PPD) technology from Oerlikon Balzers has established itself as an industry standard for the treatment of large automotive press tooling. Now the technology specialists are targeting new applications with this advanced process, offering an alternative to traditional hard-chrome processes.
Often, the required hardness qualities of parts manufactured from steel can only be obtained through suitable heat treatment. In transmission manufacturing, the case hardening process is commonly used to produce parts with a hard and wear-resistant surface and an adequate toughness in the core. A tremendous potential for rationalization, which is only partially used, becomes available if the treatment time of the case hardening process is reduced. Low pressure carburizing (LPC) offers a reduction of treatment time in comparison to conventional gas carburizing because of the high carbon mass flow inherent to the process (Ref. 1).
Contact fatigue and bending fatigue are two main failure modes of steel gears, while surface pitting and spalling are two common contact fatigue failures -- caused by alternating subsurface shear stresses from the contact load between two gear mates. And when a gear is in service under cyclic load, concentrated bending stresses exist at the root fillet -- the main driver of bending fatigue failures. Induction hardening is becoming an increasingly popular response to these problems, due to its process consistency, reduced energy consumption, clean environment and improved product quality -- but not without issues of its own (irregular residual stresses and bending fatigue). Thus a new approach is proposed here that flexibly controls the magnitude of residual stress in the regions of root fillet and tooth flank by pre-heating prior to induction hardening. Using an external spur gear made of AISI 4340 as an example, this new concept/process is demonstrated using finite element modeling and DANTE commercial software.
The complete Industry News section from the November/December 2014 issue.
Questions to Ask Your Heat Treater Provided by Justin Lefevre (Joyworks LLC, Ann Arbor, MI), Kathy Hayrynen (Applied Process, Inc., Livonia, MI) and Vasko Popovski (Applied Process, Inc.)
The oil industry is (pardon the pun) tanking. That may conjure up horrific images of other industries following suit in a domino effect of collective collapse into the overabundant oil slick the industry is currently drowning in, but not everyone is getting knocked down alongside the oil sector.
Effective case depth is an important factor and goal in gas carburizing, involving complicated procedures in the furnace and requiring precise control of many thermal parameters. Based upon diffusion theory and years of carburizing experience, this paper calculates the effective case depth governed by carburizing temperature, time, carbon content of steel, and carbon potential of atmosphere. In light of this analysis, carburizing factors at various temperatures and carbon potentials for steels with different carbon content were calculated to determine the necessary carburizing cycle time. This methodology provides simple (without computer simulation) and practical guidance of optimized gas carburizing and has been applied to plant production. It shows that measured, effective case depth of gear parts covering most of the industrial application range (0.020 inch to over 0.250 inch) was in good agreement with the calculation.
Induction hardening is becoming an increasingly popular alternative to thermochemical diffusion processes such as carburizing, and as it does so, manufacturers are on a never-ending quest to expand the scope of what's possible with the technology.
Press quenching is designed to harden steel gears while minimizing distortion, and the process is especially applied for hardening large diameter thin-wall gears, face gears and bevel gears. The dimensional control aims at maintaining flatness, out-of-round, straightness and consistency of radial size. The press quench tooling and the process design have been mainly experience-based, using a trial and error approach for implementation of new processes, new gear materials and gear configurations.
Furnaces North America Exhibition Highlights Future of Heat Treating.
An Interview with Dr. Valery Rudnev, FASM, IFHTSE Fellow, Director of Science & Technology at Inductoheat, Inc.
A Conversation with Sabine Kreuzmayr of RĂĽbig
This special advertising section highlights exhibitors from Gear Expo 2017 and ASM Heat Treat 2017.
The need for improved power transmissions that use gears and gearboxes with smaller overall dimensions and with lower noise generation has left manufacturing engineers searching for different methods of gear processing. This search has led to the requirement of hardened gears.
The complete Industry News section from the October 2013 issue of Gear Technology.
Heat treat alternative offers advantages over conventional methods.
"God is in the details," says the philosopher. What he meant was that on the scale of the universe, it's not just the galaxies, the planets, the mountain ranges, or the major rivers that are important. So are the subatomic particles and the genes. It's the little things that make all the difference.
Durability is the most important criterion used to define the quality of a gear. The freezing of metals has been acknowledged for almost thirty years as an effective method for increasing durability, or "wear life," and decreasing residual stress in tool steels. The recent field of deep cryogenics (below -300 degrees F) has brought us high temperature superconductors, the superconducting super collider, cryo-biology, and magnotehydrodynamic drive systems. It has also brought many additional durability benefits to metals.
In a very general sense, increasing the hardness of a steel gear increases the strength of the gear. However, for each process there is a limit to its effectiveness. This article contains background information on each of the processes covered. In each section what is desired and what is achievable is discussed. Typical processes are presented along with comments on variables which affect the result. By reviewing the capabilities and processes, it is possible to determine the limits to each process.
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.
Plane strain fracture toughness of twelve high-carbon steels has been evaluated to study the influence of alloying elements, carbon content and retained austenite. The steels were especially designed to simulate the carburized case microstructure of commonly used automotive type gear steels. Results show that a small variation in carbon can influence the K IC significantly. The beneficial effect of retained austenite depends both on its amount and distribution. The alloy effect, particularly nickel, becomes significant only after the alloy content exceeds a minimum amount. Small amounts of boron also appear beneficial.
Here are some of the new products and technologies available to attendees at Heat Treat 2011.
Interviews with exhibitors at ASM's Heat Treat 2013 exposition, which is co-located with Gear Expo.
In this article we will characterize the nitride layers that are generated by different nitriding processes and compare their respective wear characteristics.
ALD-Holcroft Vacuum Technologies Co. will host a two-day technical symposium at the Henry Ford Museum in Dearborn, Michigan September 23â€“ 24, 2008.
This article covers preventive maintenance and modification to machinery to induction harden different types of gear.
A study was conducted to isolate the influence of pre-rough machine processing on final dimensional distortion.
Dana Corp. is developing a process that carburizes a straight bevel gear to a carbon content of 0.8% in 60 fewer minutes than atmosphere carburizing did with an identical straight bevel.
This paper introduces new process developments in low-pressure carburizing and carbonitriding using either high-pressure gas quenching or interrupted gas quenching.
Part I, which was published in the September/October 2008 issue, covered gear materials, desired microstructure, coil design and tooth-by-tooth induction hardening. Part II covers spin hardening and various heating concepts used with it.
In the typical gear production facility, machining of gear teeth is followed by hear treatment to harden them. The hardening process often distorts the gear teeth, resulting in reduced and generally variable quality. Heat treating gears can involve many different types of operations, which all have the common purpose of producing a microstructure with certain optimum properties. Dual frequency induction hardening grew from the need to reduce cost while improving the accuracy (minimizing the distortion) of two selective hardening processes: single tooth induction and selective carburizing.
Heat treatment industry reinforces environmental/energy conservation.
Gears are designed to be manufactured, processed and used without failure throughout the design life of the gear. One of INFAC's objectives (*see p.24) is to help manufacture of gears to optimize performance and life. One way to achieve this is to identify failure mechanisms and then devise strategies to overcome them by modifying the manufacturing parameters.
Using the DANTE software, a finite element simulation was developed and executed to study the response of a carburized 5120 steel helical gear to quenching in molten salt. The computer simulation included heat-up, carburization, transfer and immersion in a molten salt bath, quenching, and air cooling. The results of the simulation included carbon distribution of phases, dimensional change, hardness, and residual stress throughout the process. The predicted results were compared against measured results for hardness, dimensions and residual stress. The excellent agreement between predictions and measured values for this carburized 5120 steel gear provides a basis for assessing the various process parameters and their respective importance in the characteristics of not only these heat-treated parts, but of other compositions and shapes.
The process of nitriding has been used to case harden gears for years, but the science and technology of the process have not remained stagnant. New approaches have been developed which are definitely of interest to the gear designer. These include both new materials and new processing techniques.
Our special advertising section featuring exhibitors from Gear Expo and ASM Heat Treat 2013
This paper examines the expanding capabilities of induction hardening of gears through methods like spin hardening or tooth-by-tooth techniques.
In order to increase the load carrying capacity of hardened gears, the distortion of gear teeth caused by quenching must be removed by precision cutting (skiving) and/or grinding. In the case of large gears with large modules, skiving by a carbide hob is more economical than grinding when the highest accuracy is not required.
Carburized helical gears with high retained austenite were tested for surface contact fatigue. The retained austenite before test was 60% and was associated with low hardness near the case's surface. However, the tested gears showed good pitting resistance, with fatigue strength greater than 1,380 MPa.
In this study, wear behavior of plasma and pulse plasma nitrided gears, made from 42CrMo4 steel, was evaluated under a lubricated sliding and pitting regime.
In the last couple of years, many research projects dealt with the determination of load limits of cylindrical worm gears. These projects primarily focused on the load capacity of the worm wheel, whereas the worm was neglected. This contribution presents investigations regarding damages such as large scores and cracks on the flanks of case-hardened worms.
In recent years, improvements in the reliability of the vacuum carburizing process have allowed its benefits to be realized in high-volume, critical component manufacturing operations. The result: parts with enhanced hardness and mechanical properties.
Geoffrey Parrish has updated and expanded his previous book: The Influence of Microstructure on the Properties of Case-Carburized Components. It now contains at least twice the material. References and bibliography include 449 citations.
Austempered irons and steels offer the design engineer alternatives to conventional material/process combinations. Depending on the material and the application, austempering may provide the producers of gear and shafts with the following benefits: ease of manufacturing, increased bending and/or contact fatigue strength, better wear resistance or enhanced dampening characteristics resulting in lower noise. Austempered materials have been used to improve the performance of gears and shafts in many applications in a wide range of industries.
In his Handbook of Gear Design (Ref.1), Dudley states (or understates): "The best gear people around the world are now coming to realize that metallurgical quality is just as important as geometric quality." Geometric accuracy without metallurgical integrity in any highly stressed gear or shaft would only result in wasted effort for all concerned - the gear designer, the manufacturer, and the customer - as the component's life cycle would be prematurely cut short. A carburized automotive gear or shaft with the wrong surface hardness, case depth or core hardness may not even complete its basic warranty period before failing totally at considerable expense and loss of prestige for the producer and the customer. The unexpected early failure of a large industrial gear or shaft in a coal mine or mill could result in lost production and income while the machine is down since replacement components may not be readily available. Fortunately, this scenario is not common. Most reputable gear and shaft manufacturers around the world would never neglect the metallurgical quality of their products.
The Instrumented Factory for Gears (INFAC) conducted a metallurgical experiment that examined the effects of carburizing process variables and types of cryogenic treatments in modifying the microstructure of the material. The initial experiment was designed so that, following the carburizing cycles, the same test coupons could be used in future experiment.
For high-quality carburized, case hardened gears, close case carbon control is essential. While tight carbon control is possible, vies on what optimum carbon level to target can be wider than the tolerance.
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.
The approximate tensile strength of any steel is measured by its hardness, Table 1. Since hardness is determined by both chemical composition and heat treatment, these are the two important metallurgical considerations in selecting gear steels.
an advancing technology and higher energy costs appear to be leading heat-treating companies in the gear industry toward cleaner, more energy-efficient processes. These processes may offer some relief to heat treaters through cooler factories and some relief to their companies through reduced energy usage.
Highly loaded gears are usually casehardened to fulfill the high demands on the load-carrying capacity. Several factors, such as material, heat treatment, or macro and micro geometry, can influence the load-carrying capacity. Furthermore, the residual stress condition also significantly influences load-carrying capacity. The residual stress state results from heat treatment and can be further modified by manufacturing processes post heat treatment, e.g. grinding or shot peening.
ASM booths 2015
Major sponsorship of an Indy car was working out well for racing fans Mike Chaplin and John Storm. On May 25, a warm, clear day, the co-founders of Contour Hardening watched from their racetrack suite as their car, a bullet on wheels, tore into sixth place at the Indy 500.
Much of the existing guidelines for making large, high-performance gears for wind turbine gearboxes exhibit a need for improvement. Consider: the large grinding stock used to compensate for heat treatment distortion can significantly reduce manufacturing productivity; and, materials and manufacturing processes are two other promising avenues to improvement. The work presented here investigates quenchable alloy steels that, combined with specifically developed Case-hardening and heat treatment processes, exhibits reduced distortion and, in turn, requires a smaller grinding stock.
In recent years, the demands for load capacity and fatigue life of gears constantly increased while weight and volume had to be reduced. To achieve those aims, most of today's gear wheels are heat treated so tooth surfaces will have high wear resistance. As a consequence of heat treatment, distortion unavoidably occurs. With the high geometrical accuracy and quality required for gears, a hard machining process is needed that generates favorable properties on the tooth surfaces and the near-surface material with high reliability.
For over 50 years, grinding has been an accepted method of choice for improving the quality of gears and other parts by correcting heat treat distortions. Gears with quality levels better than AGMA 10-11 or DIN 6-7 are hard finished, usually by grinding. Other applications for grinding include, but are not limited to, internal/external and spur/helical gear and spline forms, radius forms, threads and serrations, compressor rotors, gerotors, ball screw tracks, worms, linear ball tracks, rotary pistons, vane pump rotators, vane slots, and pump spindles.
Automotive gear manufacturers have implemented significant improvements in external planetary gear manufacturing yielding quieter gears. In addition, process stability has increased due to the post-heat treatment finishing processes employed. This article explains various complete solutions for cutting and finishing internal ring gears.
The market demand for gear manufacturers to transmit higher torques via smaller-sized gear units inevitably leads to the use of case-hardened gears with high manufacturing and surface quality. In order to generate high part quality, there is an increasing trend towards the elimination of the process-induced distortion that occurs during heat treatment by means of subsequent hard finishing.
Gear design and specification are not one and the same. They are the first two steps in making a gear. The designer sits down and mathematically defines the gear tooth, working with the base pitch of the gear, the pressure angle he wants to employ, the number of teeth he wants, the lead, the tooth thickness, and the outside, form and root diameters. With these data, the designer can create a mathematical model of the gear. At this stage, he will also decide whether the gear will be made from existing cutting tools or whether new tools will be needed, what kind of materials he will use, and whether or not he will have the gear heat treated and finished.
You have challenges. We all do. If your challenges are related to any aspect of gear design, manufacturing, inspection, heat treating or use, the solutions can be found at Motion + Power Technology Expo, which takes place October 15â€“17 in Detroit.
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.
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.).
Whether gear engineers have to replace an old gear which is worn out, find out what a gear's geometry is after heat treatment distortion, or just find out parameters of gears made by a competitor, sometimes they are challenged with a need to determine the geometry of unknown gears. Depending on the degree of accuracy required, a variety of techniques are available for determining the accuracy of an unknown gear. If a high degree of precision is important, a gear inspection device has to be used to verify the results. Frequently, several trial-and-error attempts are made before the results reach the degree of precision required.
The search for greater gear life involves improvement in cost, weight and increased power output. There are many events that affect gear life, and this paper addresses those relating to fatigue, gear tooth pitting, fatigue strength losses due to the heat treating processes and shot peening technique. The capability of shot peening to increase fatigue strength and surface fatigue life eliminate machine marks which cause stress risers, and to aid in lubrication when properly controlled, suggests increased use and acceptance of the process.
At Andrew Tool, CMMs have been an integral part of their manufacturing processes for years, but they had never faced a project with such intricate measurements, tight tolerances, heat treatments and a very short time frame requirement.
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.
News from around the Gear Industry
The complete industry news section from the May 2018 issue of Gear Technology.
September 27-29. American Society for Metals 11th Annual Heat Treating Conference October 10-12. AGMA Fall Technical Meeting. Fairmont Hotel, New Orleans, LA November 1-3. SME Gear Processing and Manufacturing Clinic, Sheraton Meridian, Indianapolis, IN
News Items About heat treat
1 Grieve 1200°F Walk-in Oven Offers On-Site Heat Treating (July 7, 2015)
No. 901 is a 1200ºF (649ºC) electrically-heated walk-in oven from Grieve, currently used for heat treating at the customer&rsqu... Read News
2 Machine Tool Builders Launches Diablo Furnaces Heat Treating Company (June 27, 2017)
Machine Tools Builders has launched a spinoff company to build a new line of heat treating furnaces to better service their customers. Th... Read News
3 Modern Heat Treat Adds Seventh AFC-Holcroft Batch Furnace (November 19, 2014)
Modern Heat Treat, a commercial heat treating operation located in Richland Hills, Texas, is prepared to take delivery of a new AFC-Holcr... Read News
4 AFC-Holcroft Ships Heat Treating Furnace to Stamping Manufacturer (January 21, 2015)
A large stamping manufacturer has ordered a mesh belt austempering furnace system from AFC-Holcroft, a manufacturer of heat treating furn... Read News
5 Contour Hardening Mexico Heat Treating Facility Completes ISO/TS Certification (September 18, 2015)
Contour Hardening, Inc. recently announced the ISO/TS certification of its heat treating service facility in Silao, Guanajuato, Mexico. T... Read News
6 Bodycote Announces Opening of Two Heat Treatment Plants in Southeast US (January 19, 2016)
Bodycote has announced that the company will open two new heat treatment plants in Southeastern USA.In Covington, GA, a new plant will op... Read News
7 Bodycote to Open San Luis Potosi Heat Treatment Plant (June 15, 2016)
Bodycote announced that the company will open a new, state-of-the-art heat treatment plant in San Luis Potosi, Mexico. Mexico is one of t... Read News
8 Bodycote Opens Georgia Heat Treatment Plant (July 1, 2016)
Bodycote recently announced that its new heat treatment plant in Covington, GA is now open. The brand new 60,0002 ft facility, establishe... Read News
9 ASM Heat Treat Preview: Inductoheat Booth 1611 (September 28, 2011)
Inductoheat provides quality induction heating and heat treating equipment with flexible and innovative systems that offer long-life perf... Read News
10 Hubbard-Hall Increases Heat Treat Salts Capacity (January 19, 2017)
Hubbard-Hall has announced additional capacity for heat treat salts and corresponding services, effective immediately. "As a result ... Read News
11 Solar Installs Furnace for Mid-Size Vacuum Heat Treating and Brazing (April 2, 2014)
Vacuum heat treat services expert, Solar Atmospheres of Western PA, recently announced the installation of a new high-temperature, high-purity, production-scale, 2-bar vacuum furnace... Read News
12 Seco/Warwick Delivers Vacuum Heat Treatment System to Galvamet (May 9, 2017)
Seco/Warwick is developing a vacuum heat treatment system equipped with a 10 bar abs. gas quenching system, the sixth in a series of syst... Read News
13 Nevada Heat Treating Invests in New Equipment (April 4, 2011)
Nevada Heat Treating has recently placed orders for two new advanced heat treating furnaces. This represents a capital investment of appr... Read News
14 Solar Receives Nadcap Merit Status for Vacuum Heat Treating (January 29, 2014)
Solar Atmospheres of Western PA (SAWPA) announces that it has been awarded Nadcap Merit status for vacuum heat treating and brazing of me... Read News
15 Inductoheats Heat Treating System Compatible with Numerous Power Supplies (January 16, 2007)
The InductoScan modular heat treat system from Inductoheat is designed to increase versatility, reduce maintenance and installation cost... Read News
16 Applied Process to Build New Heat Treatment Plant in Arkansas (March 13, 2018)
Applied Process, Inc. will expand with a new multi-million-dollar heat treatment plant in Fort Smith, Ark. The 51,000-square-foot plant w... Read News
17 Grieve No. 934 Oven Utilized for Heat Treating Applications (January 18, 2019)
No. 934 is an 850°F (454°C), cabinet oven from Grieve, currently used for heat treating at the customer’s facility. Workspa... Read News
18 Bodycote Invests in North American Heat Treat Facility (January 28, 2019)
Bodycote is pleased to announce plans to open a new heat treating facility in Elgin, Illinois. The new facility will include advanced hea... Read News
19 Modern Heat Treat Expands Production Capability with AFC Holcroft Equipment (March 18, 2019)
In support of its continued growth, Modern Heat Treat, a commercial heat treating operation located in Richland Hills, Texas (USA), has a... Read News
20 CAS DataLoggers Offer Monitoring Solutions for Heat Treaters (March 30, 2020)
CAS DataLoggers provided the temperature data logging solution for a factory with multiple lines of (fixed) heat treating ovens. The fact... Read News
21 Grieve No. 852 Walk-In Oven Designed for Customer for Heat Treating and Baking Varnish (June 30, 2017)
No. 852 is an 850°F (454°C), high temperature walk-in oven from Grieve, currently used for heat treating and baking varnish at th... Read News
22 Grieve Universal Oven Offers Variety of Heat Treatments (September 4, 2019)
No. 841 is a 650°F (343°C), universal oven from Grieve, currently used for a variety of heat treatments at the customer’s f... Read News
23 ASM Heat Treat Preview: Metallurgical High Vacuum Booth 1639 (September 12, 2013)
The HS430 Survivor pumps incorporate multiple oil filters that extend the life of the pump by removing particles and acid which are har... Read News
24 Roger Jones Named President of ASM Heat Treating Society (September 30, 2013)
Roger A. Jones, corporate president of Solar Atmospheres, has been named president of the ASM Heat Treating Society (HTS) for the 2013-20... Read News
25 Alfe Heat Treating Celebrates 25th Anniversary (January 31, 2005)
Alfe Heat Treating of Fort Wayne, IN, recently celebrated its 25th anniversary. The company currently has nine facilities throughout t... Read News
26 Ipsen Recaps Successful ASM Heat Treat Show (September 26, 2013)
The 27th ASM Heat Treating Conference and Exposition attendees were clear for takeoff at booth #1529. Ipsen offered... Read News
27 Applied Process Commissions Heat Treating Facility in China (February 19, 2007)
Applied Process CEO John Keough recently commissioned AP Suzhou as the newest member of the Applied Process family of companies. The... Read News
28 Complete Heat Treating Acquires Wisconsin Steel Industries (September 11, 2013)
Complete Heat Treating, LLC announced the completion of its acquisition of all assets and equipment of the former Wisconsin Steel Industr... Read News
29 Ipsen Delivers Custom Heat Treat Solutions (March 14, 2013)
Customers from a variety of industries have had the opportunity to discuss with Ipsen what matters most to them when it comes to heat tre... Read News
30 Alfe Heat Treating Hires General Manager (March 2, 2005)
Alfe Heat Treat Corp. hired Jerry Brasiola as general manager of their Defiance, OH, division. Most recently, Brasiola was plant manag... Read News
31 Solar Atmospheres Awarded 2012 Commercial Heat Treater of the Year (October 15, 2012)
Solar Atmospheres of Western PA (SAWPA) was awarded the 2012 Commercial Heat Treater of the Year Award by the Metal Treating Institute in... Read News
32 Advanced Heat Treat Installing $1.5 Million Large Capacity Ion Nitriding Vessel (January 4, 2007)
Advanced Heat Treat Corp. is installing one of the world's largest ion nitriding vessels in their new Cullman, AL service center, cur... Read News
33 Madeira Appointed VP of Heat Treating (January 28, 2011)
Inductoheat, Inc., located in Madison Heights, Michigan, has recently appointed Robert Madeira as the vice president of Heat Treatin... Read News
34 Ipsen Projects Healthy Sales of Continuous Heat Treatment Furnaces (January 28, 2013)
As new approaches to energy-efficient furnace operation are met with heightened interest by a diverse customer base, Ipsen has reported h... Read News
35 Bodycote Opens New Illinois Heat Treatment Facility (December 14, 2020)
Bodycote recently announced the opening of a new facility in Elgin, Illinois.The Elgin facility upgrades the company's capabilities a... Read News
36 Solar and ASM Offer Vacuum Heat Treating Course (February 5, 2014)
Solar Atmospheres and ASM International at Materials Park in Ohio have partnered to offer a new Vacuum Heat Treating Course.This new cour... Read News
37 Grieve No. 1030 Oven Provides Heat Treat for Large Gears (January 19, 2017)
No. 1030 is a 550 degrees Fahrenheit floor-level electric cabinet oven from Grieve, currently used for heating large gears at the custome... Read News
38 Bodycote to Open New Illinois Heat Treatment Facility (May 11, 2020)
Bodycote will open a new state of the art facility in Elgin, Illinois, USA.The new purpose built facility has been designed as a replacem... Read News
39 Seco/Warwick Offers Heat Treatment 4.0 Seminar (August 12, 2019)
Seco/Warwick will offer a Heat Treatment 4.0 Seminar September 10-12, 2019 in the heart of the Karkonosze Mountains in the GoĹ‚Ä™biewski ... Read News
40 Solar Atmospheres of Western PA Receives MedAccred Heat Treating Accreditation (April 3, 2018)
Solar Atmospheres of Western PA announced that it has received the prestigious MedAccred Heat Treating accreditation. Becoming only the e... Read News
41 Ipsen Offers Credit Toward New Heat Treating Equipment (August 14, 2017)
Ipsen believes that one of the most valuable things a company can do is invest in others. They are also committed to advancing the heat-t... Read News
42 Solar Atmospheres Constructs Climate-Controlled Vacuum Heat Treat Environment (June 29, 2017)
After surviving one of the hottest and most humid summer seasons on record, Solar Atmospheres of Western PA decided to construct a climat... Read News
43 ALD Vacuum Systems Sells SyncroTherm Vacuum Heat Treating System (May 10, 2017)
ALD Vacuum Systems, Inc. has received a purchase order from a North American based aerospace manufacturer for a SyncroTherm brand, fully-... Read News
44 Solar Atmospheres of California Awarded Nadcap 24-Month Merit Status for Heat Treating (August 4, 2016)
Solar Atmospheres of California announced that it has been awarded Nadcap 24-month Merit status for Heat Treating. Achieving 24-month mer... Read News
45 Companies Recognize Correlation between Education and Heat Treat Success (May 1, 2014)
With an ever-increasing need for first-hand knowledge of thermal processing and the intricate functions of specific equipment... Read News
46 Solar Atmospheres Selected to Heat Treat Drill for Venus Expedition (April 29, 2016)
Honeybee Robotics, with three locations in the USA, received NASA funding awards to contribute to developing future planetary exploration... Read News
47 McInnes Rolled Rings Completes Heat Treat Expansion (March 2, 2016)
McInnes Rolled Rings has completed an $8 million, 25,000-square-foot expansion to its current manufacturing facility. The addition expand... Read News
48 REX Heat Treat Adds Super IQ Hybrid System from Seco/Warwick (August 26, 2020)
The Super IQ hybrid system, a conventional and vacuum furnace in one, premiered in October at ASM2019 in Detroit and now it operates for ... Read News
49 Roger Jones Receives 2015 HTS George H. Bodeen Heat Treating Achievement Award (June 29, 2015)
Roger Jones, corporate president of Solar Atmospheres, Inc., Souderton, PA, was recently named the recipient of the 2015 George H. Bodeen... Read News
50 ALD-Holcroft to Provide SyncroTherm Heat Treating System to Woodward (May 15, 2015)
ALD-Holcroft (Wixom, MI) recently entered into an agreement with Woodward, Inc. (Fort Collins, CO) to provide a fully-integrated SyncroTh... Read News
51 FPM Heat Treating Receives Nadcap Accreditation (April 20, 2015)
FPM Heat Treating in Elk Grove Village, IL announced that it has received an additional Nadcap Scope of Accreditation for carburizing, c... Read News
52 Solar Develops Heat Treat Process for Bright 17-7 PH Stainless Steel (August 20, 2014)
Using advanced gas cooling technology and out-of-the-box thinking, Solar Atmospheres has developed a unique three-step process to austeni... Read News
53 Matlab Increases Heat Treating Capaciy for Gears (January 4, 2005)
Metlab has completed the upgrade of one of its large pit carburizing furnaces, which doubles its capabilities for carburizng, nitriding, ... Read News