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What follows is the first of three articles we will be running on ISO 9000 and what it means for the gear industry. This first article will cover what ISO 9000 is, what some of its benefits - and problems - are, and whether your company should be a candidate for this certification process. In our next issue, we will consider the important question of how, when, and if to hire an ISO 9000 consultant. The final article in this series will discuss ways to save money while streamlining the certification process in your company.
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.
Until recently, there was a void in the quality control of gear manufacturing in this country (Ref. 1). Gear measurements were not traceable to the international standard of length through the National Institute of Standards and Technology (NIST). The U.S. military requirement for traceability was clearly specified in the military standard MIL-STD-45662A (Ref. 2). This standard has now been replaced by commercial sector standards including ISO 9001:1994 (Ref. 3), ISO/IEC Guide 25 (Ref, 4), and the U.S. equivalent of ISO/IEC Guide 25 - ANSI/NCSL Z540-2-1997 (Ref. 5). The draft replacement to ISO/IEC Guide 25 - ISO 17025 states that measurements must either be traceable to SI units or reference to a natural constant. The implications of traceability to the U.S. gear industry are significant. In order to meet the standards, gear manufacturers must either have calibrated artifacts or establish their own traceability to SI units.
On of the key questions confronting any company considering ISO 9000 certification is, how much is this going to cost? The up-front fees are only the beginning. Dissect the ISO 9000 certification procedure with an eye for hidden costs, and two segments of the process will leap out - the cost of consultants and the cost of making in-house improvements for the sake of passing certification. Most of these costs can be controlled by careful selection f the right consultant in the first place.
With all the heated debate and hoopla surrounding ISO 9000 certification, everyone seems to have an opinion about whether to sign up. Executives in the gear industry are flooded with information and ideas that often seem at odds. Gear Technology asked AGMA executive director Joe T. Franklin, Jr. to give an industry perspective on the pros and cons of ISO 9000 certification.
Much about ISO 9000 is the subject of noisy debate. But on one thing almost everyone, true believers and critics alike, agrees: Getting ISO 9000 certification can be expensive. Companies can expect to spend at least $35,000 for basic certification and six-month checkup fees over a three-year period. These figures do not include hidden costs like time and money spent on internal improvements required to meet ISO 9000 certification. But the really big-ticket items in the process are employee time and the cost of bringing in outside consultants. Many ISO 9000 consultants charge upwards of $1,800 a day.
One of the best ways to learn the ISO 6336 gear rating system is to recalculate the capacity of a few existing designs and to compare the ISO 6336 calculated capacity to your experience with those designs and to other rating methods. For these articles, I'll assume that you have a copy of ISO 6336, you have chosen a design for which you have manufacturing drawings and an existing gear capacity calculation according to AGMA 2001 or another method. I'll also assume that you have converted dimensions, loads, etc. into the SI system of measurement.
ISO 9000 is the latest hot topic in marketing and manufacturing circles. Everyone seems to be talking about it, but few seem to understand it completely. depending on whom one talks to, it's either the greatest thing to hit industry since the assembly line, another cash cow for slick consultants, a conspiracy on the part of Europeans to dominate global markets, or the next necessary step to compete in the global economy of the twenty-first century. It may be all of the above.
I noted with interest the beginning of Gear Technology's three-part series on ISO 9000 certification. I also recently attended Brown & Sharpe's/Leitz gear metrology seminar. Both events caused me to smile and reflect.
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.
In Part I differences in pitting ratings between AGMA 218, the draft ISO standard 6336, and BS 436:1986 were examined. In this part bending strength ratings are compared. All the standards base the bending strength on the Lewis equation; the ratings differ in the use and number of modification factors. A comprehensive design survey is carried out to examine practical differences between the rating methods presented in the standards, and the results are shown in graphical form.
This is the third article in a series exploring the new ISO 6336 gear rating standard and its methods of calculation. The opinions expressed herein are htose of the author as an individual. They do not represent the opinions of any organization of which he is a member.
The purpose of this article is to discuss ISO 4156/ANSI B92.2M-1980 and to compare it with other, older standards still in use. In our experience designing and manufacturing spline gauges and other spline measuring or holding devices for splined component manufacturers throughout the world, we are constantly surprised that so many standards have been produced covering what is quite a small subject. Many of the standards are international standards; others are company standards, which are usually based on international standards. Almost all have similarities; that is, they all deal with splines that have involute flanks of 30 degrees, 37.5 degrees or 45 degrees pressure angle and are for the most part flank-fitting or occasionally major-diameter-fitting.
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 study of AGMA 218, the draft ISO standard 6336, and BS 436: 1986 methods for rating gear tooth strength and surface durability for metallic spur and helical gears is presented. A comparison of the standards mainly focuses on fundamental formula and influence factors, such as the load distribution factor, geometry factor, and others. No attempt is made to qualify or judge the standards other than to comment on the facilities or lack of them in each standard reviewed. In Part I a comparison of pitting resistance ratings is made, and in the subsequent issue, Part II will deal with bending stress ratings and comparisons of designs.
The authors of last issue's article comparing AGMA, ISO and BS methods for Pitting Resistance Ratings are commended. Trying to compare various methods of rating gears is like hitting a moving target in a thick forest. The use of different symbols, presentations, terminology, and definitions in these standards makes it very difficult. But the greatest problem lies with the authors' use of older versions of these documents. ISO drafts and AGMA standards have evolved at the same time their work was accomplished and edited.
“The gear marketplace is a global marketplace.” Bill Bradley says it easily, with no special emphasis. The vice president of AGMA’s technical division sees the statement as an obvious fact.
In today’s globalized manufacturing, all industrial products having dimensional constraints must undergo conformity specifications assessments on a regular basis. Consequently, (standardization) associated with GD&T (geometrical dimensioning and tolerancing) should be un-ambiguous and based on common, accepted rules. Of course gears - and their mechanical assemblies - are special items, widely present in industrial applications where energy conversion and power transmission are involved.
Gleason 350GMS helps put higher quality, more reliable gears into its next-generation TC10 automatic transmission.
There exists an ongoing, urgent need for a rating method to assess micropitting risk, as AGMA considers it a “a very significant failure mode for rolling element bearings and gear teeth — especially in gearbox applications such as wind turbines.”
The objective of this paper is to demonstrate that transmission gears of rotary-wing aircraft, which are typically scrapped due to minor foreign object damage (FOD) and grey staining, can be repaired and re-used with signifi cant cost avoidance. The isotropic superfinishing (ISF) process is used to repair the gear by removing surface damage. It has been demonstrated in this project that this surface damage can be removed while maintaining OEM specifications on gear size, geometry and metallurgy. Further, scrap CH-46 mix box spur pinions, repaired by the ISF process, were subjected to gear tooth strength and durability testing, and their performance compared with or exceeded that of new spur pinions procured from an approved Navy vendor. This clearly demonstrates the feasibility of the repair and re-use of precision transmission gears.
As the international business community grows closer together, the need for understanding differences between national and international gear rating standards becomes increasingly important for U.S. gear manufacturers competing in the world market.
I support Clem Miller (Viewpoint May/June) in his skepticism of ISO 9000. The metrology of gears is important, but in the present state of the art, manufacture is more accurate than design.
The common calculation methods according to DIN 3990 and ISO 6336 are based on a comparison of occurring stress and allowable stress. The influence of gear size on the load-carrying capacity is considered with the size factors YX (tooth root bending) and ZX (pitting), but there are further influences, which should be considered. In the following, major influences of gear size on the load factors as well as on the permissible tooth root bending and contact stress will be discussed.
In ParI 1 several scuffing (scoring) criteria were shown ultimately to converge into one criterion, the original flash temperature criterion according to Blok. In Part 2 it will be shown that all geometric influences may be concentrated in one factor dependent on only four independent parameters, of which the gear ratio, the number of teeth of the pinion, and the addendum modification coefficient of the pinion are significant.
Results from the Technical University of Munich were presented in a previous technical article (see Ref. 4). This paper presents the results of Ruhr University Bochum. Both research groups concluded that superfinishing is one of the most powerful technologies for significantly increasing the load-carrying capacity of gear flanks.
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The gear companies enjoying the most success in today’s global market are those that firmly believe quality is much more than expert craftsmanship and foolproof inspection methodologies.
The load capacity rating of gears had its beginning in the 18th century at Leiden University when Prof. Pieter van Musschenbroek systematically tested the wooden teeth of windmill gears, applying the bending strength formula published by Galilei one century earlier. In the next centuries several scientists improved or extended the formula, and recently a Draft International Standard could be presented.
In several applications like hoisting equipment and cranes, open gears are used to transmit power at rather low speeds (tangential velocity < 1m/s) with lubrication by grease. In consequence those applications have particularities in terms of lubricating conditions and friction involved, pairing of material between pinion and gear wheel, lubricant supply, loading cycles and behavior of materials with significant contact pressure due to lower number of cycles.
How should we consider random helix angle errors fHβ and housing machining errors when calculating KHβ? What is a reasonable approach?
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.
Companies weigh in on green technology and sustainable efforts.
Companies around the world are learning to embrace the environment, and the gear industry is no exception. This special section takes a look at how some gear manufacturers are doing their part to conserve resources, preserve and protect the environment, and give back to the land. What we’ve found is that adopting environmental measures is far more than just good corporate citizenship. For many gear industry companies, good environmental practices also turn out to be good for the bottom line.
There is a great need for future powertrains in automotive and industrial applications to improve upon their efficiency and power density while reducing their dynamic vibration and noise initiation. It is accepted that planetary gear transmissions have several advantages in comparison to conventional transmissions, such as a high power density due to the power division using several planet gears. This paper presents planetary gear transmissions, optimized in terms of efficiency, weight and volume.
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.
This is the fourth and final article in a series exploring the new ISO 6336 gear rating standard and its methods of calculation. The opinions expressed herein are those of the author as an individual. They do not represent the opinions of any organization of which he is a member.
Gear-loaded tooth contact analysis is an important tool for the design and analysis of gear performance within transmission and driveline systems. Methods for the calculation of tooth contact conditions have been discussed in the literature for many years. It's possible the method you've been using is underestimating transmission error in helical gears. Here's why.
The first edition of the international calculation method for micropitting—ISO TR 15144–1:2010—was just published last December. It is the first and only official, international calculation method established for dealing with micropitting. Years ago, AGMA published a method for the calculation of oil film thickness containing some comments about micropitting, and the German FVA published a calculation method based on intensive research results. The FVA and the AGMA methods are close to the ISO TR, but the calculation of micropitting safety factors is new.
I’d like to apologize to the dedicated people working on revisions to the AGMA 925 standard and the Technical Report ISO 15144-1, both of which deal with the issue of micropitting. In the March/April issue of Gear Technology, we published an opinion piece in our Voices column that harshly criticized the methods for predicting micropitting outlined in ISO 15144-1.
Measurement institutions of seven different countries — China, Germany, Japan, Thailand, Ukraine, United Kingdom and the U.S. — participated in the implementation of the first international comparison of involute gear measurement standards. The German metrology institute Physikalisch-Technische Bundesanstalt (PTB) was chosen as the pilot laboratory as well as the organizer. Three typical involute gear measurement standards provided by the PTB were deployed for this comparison: a profile, a helix and a pitch measurement standard. In the final analysis, of the results obtained from all participants, the weighted mean was evaluated as reference value for all 28 measured parameters. However, besides the measurement standards, the measured parameters, and, most importantly, some of the comparison results from all participants are anonymously presented. Furthermore, mishandling of the measurement standards as occurred during the comparison will be illustrated.
Surface-hardened, sintered powder metal gears are increasingly used in power transmissions to reduce the cost of gear production. One important problem is how to design with surface durability, given the porous nature of sintered gears. Many articles have been written about mechanical characteristics, such as tensile and bending strength, of sintered materials, and it is well-known that the pores existing on and below their surfaces affect their characteristics (Refs. 1-3). Power transmission gears are frequently employed under conditions of high speed and high load, and tooth surfaces are in contact with each other under a sliding-rolling contact condition. Therefore it is necessary to consider not only their mechanical, but also their tribological characteristics when designing sintered gears for surface durability.
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.
This paper shows an experimental study on the fatigue lifetime of high-heat polyamide (Stanyl) gears running in oil at 140°C. Based on previous works (Refs. 1–2), an analysis is made correcting for tooth bending and calculating actual root stresses. A comparison with tensile bar fatigue data for the same materials at 140°C shows that a good correlation exists between gear fatigue data and tensile bar fatigue data. This insight provides a solid basis for gear designers to design plastic gears using actual material data.
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.
Sivyer Steel Corporation, Bettendorf, IA, an ISO-9002-certified casting specialist, is familiar with tackling tough jobs. The company has built an international reputation as a supplier of high-integrity castings, especially those which require engineering and/or full machining. Its not unusual for Sivyer's customers, especially those in the mining, recycling, power generation, valve and nuclear fields, to ask the foundry to produce a one-of-a-kind casting - often something revolutionary - but AnClyde Engineered Products' request was a special challenge, even for Sivyer.
Acquisitions, Contracts, and ISO 9000 Certification
With the publishing of various ISO draft standards relating to gear rating procedures, there has been much discussion in technical papers concerning the various load modification factors. One of the most basic of parameters affecting the rating of gears, namely the endurance limit for either contact or bending stress, has not, however, attracted a great deal of attention.
Mineral-oil-base lubricants show a significant decrease of kinematic viscosity with rising temperature, as exemplified in Figure 1 by lubricants for vehicle gears. An important attribute of lubricants is their viscosity index (VI), according to DIN/ISO 2909 (Ref. 4). Viscosity index is a calculated coefficient, which characterizes the change of viscosity of lubricants as a function of temperature. A high viscosity index represents a low variation of viscosity due to temperature and vice versa. A low viscosity-temperature-dependence is required for lubricants that are operated at significantly varying temperature conditions, such as vehicle engine and gear lubricants in summer and winter time. This way, the oils remain flowing and pumpable at low temperatures on the one hand; and on the other hand, sufficiently thick lubricant films can be formed at higher temperatures for a safe separation of the surfaces.
This article discusses applications of statistical process capability indices for controlling the quality of tooth geometry characteristics, including profile and lead as defined by current AGMA-2015, ISO-1328, and DIN-3960 standards. It also addresses typical steps to improve manufacturing process capability for each of the tooth geometry characteristics when their respective capability indices point to an incapable process.
This paper outlines the comparison of efficiencies for worm gearboxes with a center distance ranging from 28 – 150 mm that have single reduction from 5 to 100:1. Efficiencies are calculated using several standards (AGMA, ISO, DIN, BS) or by methods defined in other bibliographic references. It also deals with the measurement of torque and temperature on a test rig — required for the calibration of an analytical model to predict worm gearbox efficiency and temperature. And finally, there are examples of experimental activity (wear and friction measurements on a blockon- ring tribometer and the measurements of dynamic viscosity) regarding the effort of improving the efficiency for worm gear drivers by adding nanoparticles of fullerene shape to standard PEG lubricant
Alongside the macro test parameters on tooth flanks for profile and tooth traces, surface properties (roughness) play a decisive role in ensuring proper toothed gear function. This article addresses roughness measurement systems on tooth flanks. In addition to universal test equipment, modified test equipment based on the profile method for use on gears is addressed in particular. The equipment application here refers to cylindrical gear flanks and bevel gear flanks. The most important roughness parameters, as well as the implementation of the precise measurement procedure will also be described under consideration of the applicable DIN EN ISO standards as well as the current VDI/VDE Directive 2612 Sheet 5.
Faithful Gear Technology readers may recall that our July 2009 issue contained an update of the deliberations provided by Bill Bradley. Now, almost two years later, there is an ISO/IEC wind turbine gearbox standard out for draft international standard ballot (ballot closes 2011-05-17).
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.
Flute Index Flute index or spacing is defined as the variation from the desired angle between adjacent or nonadjacent tooth faces measured in a plane of rotation. AGMA defines and provides tolerance for adjacent and nonadjacent flute spacing errors. In addition, DIN and ISO standards provide tolerances for individual flute variation (Fig. 1).
Tooth contact under load is an important verification of the real contact conditions of a gear pair and an important add-on to the strength calculation according to standards such as ISO, AGMA or DIN. The contact analysis simulates the meshing of the two flanks over the complete meshing cycle and is therefore able to consider individual modifications on the flank at each meshing position.
Influences of Load Distribution and Tooth Flank Modifications as Considered in a New, DIN/ISO-Compatible Calculation Method
AGMA has started to replace its 2000-A88 standard for gear accuracy with a new series of documents based largely on ISO standards. The first of the replacement AGMA standards have been published with the remainder coming in about a year. After serving as a default accuracy specification for U.S. commerce in gear products for several decades, the material in AGMA 2000-A88 is now considered outdated and in need of comprehensive revision.
In comparison to the visionary Industry 4.0 — or the Fourth Industrial Revolution — the machine tool industry can appear rather down-to-earth.
The focus of the following presentation is two-fold: 1) on tests of new geometric variants; and 2) on to-date, non-investigated operating (environmental) conditions. By variation of non-investigated eometric parameters and operation conditions the understanding of micropitting formation is improved. Thereby it is essential to ensure existent calculation methods and match them to results of the comparison between large gearbox tests and standard gearbox test runs to allow a safe forecast of wear due to micropitting in the future.
The gear tooth fillet is an area of maximum bending stress concentration. However, its profile is typically less specified in the gear drawing and hardly controlled during gear inspection in comparison with the gear tooth flanks. This paper presents a fillet profile optimization technique for gears with symmetric and asymmetric teeth based on FEA and a random search method. It allows achieving substantial bending stress reduction in comparison with traditionally designed gears. This bending stress reduction can be traded for higher load capacity, longer lifetime, lower noise and vibration and cost reduction.
There is an increasing significance of screw helical and worm gears that combine use of steel and plastics. This is shown by diverse and continuously rising use in the automotive and household appliance industries. The increasing requirements for such gears can be explained by the advantageous qualities of such a material combination in comparison with that of the traditional steel/bronze pairing.
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).
The objective of this work is to introduce a method for the calculation of the tooth root load carrying capacity for gears, under consideration of the influence of the defect size on the endurance fatigue strength of the tooth root. The theoretical basis of this method is presented in this paper as well as the validation in running tests of helical and beveloid gears with different material batches, regarding the size distribution of inclusions. The torque level for a 50 percent failure probability of the gears is evaluated on the test rig and then compared to the results of the simulation. The simulative method allows for a performance of the staircase method that is usually performed physically in the back-to-back tests for endurance strength, as the statistical influence of the material properties is considered in the calculation model. The comparison between simulation and tests shows a high level of accordance.
Although gear geometry and the design of asymmetric tooth gears are well known and published, they are not covered by modern national or international gear design and rating standards. This limits their broad implementation for various gear applications, despite substantial performance advantages in comparison to symmetric tooth gears for mostly unidirectional drives. In some industries — like aerospace, that are accustomed to using gears with non-standard tooth shapes — the rating of these gears is established by comprehensive testing. However, such testing programs are not affordable for many other gear drive applications that could also benefit from asymmetric tooth gears.
Free form milling of gears becomes more and more important as a flexible machining process for gears. Reasons for that are high degrees of freedom as the usage of universal tool geometry and machine tools is possible. This allows flexible machining of various gear types and sizes with one manufacturing system. This paper deals with manufacturing, quality and performance of gears made by free form milling. The focus is set on specific process properties of the parts. The potential of free form milling is investigated in cutting tests of a common standard gear. The component properties are analyzed and flank load-carrying capacity of the gears is derived by running trials on back-to-back test benches. Hereby the characteristics of gears made by free form milling and capability in comparison with conventionally manufactured gears will be shown.
At first sight the appearance of 5-axis milling for bevel gears opens new possibilities in flank form design. Since in comparison to existing machining methods applying cutter heads no kinematic restrictions exist for 5-axis milling technology, any flank form can be machined. Nevertheless the basic requirements for bevel gears did not change. Specifications and functional requirements like load carrying capacity and running behavior are still increasing demands for design and manufacturing. This paper describes the demands for gear design and gives an overview about different design principles in the context of the surrounding periphery of the gear set.
A study was conducted to isolate the influence of pre-rough machine processing on final dimensional distortion.
Imagine a shop supervisor with a three-gear drivetrain tattooed on his bicep or a saleswoman with a tiny spur gear silhouetted just above her ankle.
Optimization is applied to the design of a spiral bevel gear reduction for maximum life at a given size. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial values. Gear tooth bending strength and minimum contact ration under load are included in the active constraints. The optimal design of the spiral bevel gear reduction includes the selection of bearing and shaft proportions in addition to gear mesh parameters. System life is maximized subject to a fixed back-cone distance of the spiral bevel gear set for a specified speed ratio, shaft angle, input torque and power. Significant parameters in the design are the spiral angle, the pressure angle, the numbers of teeth on the pinion and gear and the location and size of the four support bearings. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for gradient optimization. After finding the continuous optimum, a designer can analyze near-optimal designs for comparison and selection. Design examples show the influence of the bearing lives on the gear parameters in the optimal configurations. For a fixed back-cone distance, optimal designs with larger shaft angles have larger service lives.
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.
How important is the right choice of coupling in determining successful machine design? Consider the following example. A transmission of appropriate size was needed to transfer the speed of the engine driver to that of the driven generator. The transmission was properly selected and sized to endure the rated power requirements indefinitely, but after only a short time in operation, it failed anyway. What happened? The culprit in the case was a coupling. It provided the necessary power and protection against misalignment but it lacked the ability to isolate the gears from the torque peaks of the diesel engine.
It has previously been demonstrated that one gear of an interchangeable series will rotate with another gear of the same series with proper tooth action. It is, therefore, evident that a tooth curve driven in unison with a mating blank, will "generate" in the latter the proper tooth curve to mesh with itself.
This paper presents a unique approach and methodology to define the limits of selection for gear parameters. The area within those limits is called the “area of existence of involute gears” (Ref. 1). This paper presents the definition and construction of areas of existence of both external and internal gears. The isograms of the constant operating pressure angles, contact ratios and the maximum mesh efficiency (minimum sliding) isograms, as well as the interference isograms and other parameters are defined. An area of existence allows the location of gear pairs with certain characteristics. Its practical purpose is to define the gear pair parameters that satisfy specific performance requirements before detailed design and calculations. An area of existence of gears with asymmetric teeth is also considered.
When designing a gear set, engineers usually want the teeth of the gear (Ng) and the pinion (Np) in a "hunting" mesh. Such a mesh or combination is defined as one in which the pinion and the gear do not have any common divisor by a prime number. If a mesh is "hunting," then the pinion must make Np x Ng revolutions before the same pinion tooth meshes with the same gear space. It is often easy to determine if a mesh is hunting by first determining if both the pinion and the gear teeth are divisible by 2,3,5,7,etc. (prime numbers). However, in this age of computerization, how does one program the computer to check for hunting teeth? A simple algorithm is shown below.
In comparison with the traditional gear design approach based on preselected, typically standard generating rack parameters, the Direct Gear Design method provides certain advantages for custom high-performance gear drives that include: increased load capacity, efficiency and lifetime; reduced size, weight, noise, vibrations, cost, etc. However, manufacturing such directly designed gears requires not only custom tooling, but also customization of the gear measurement methodology. This paper presents definitions of main inspection dimensions and parameters for directly designed spur and helical, external and internal gears with symmetric and asymmetric teeth.
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.
Gear Expo 99, AGMA's biennial showcase for the gear industry, has left the Rust Belt this year and landed in Music City U.S.A., Nashville, Tennessee. The event, with exhibitors from around the globe showing off the latest in gear manufacturing as well as metal working processes, will be held at the Nashville Convention Center, October 24-27, 1999. According to Kurt Medert, AGMA vice president and Gear Expo show manager, "In choosing Nashville, AGMA;s Trade Show Advisory Council found a city that is an excellent trade show site. It has the right mix of convention center, nearby hotels, and a clean downtown area with entertainment readily available for the exhibitors and visitors alike. Nashville is in the heart of southern industry, which we see as a focus of growth for the gear industry and its customers."
The present article contains a preliminary description of studies carried out by the authors with a view toward developing asymmetrical gear teeth. Then a comparison between numerous symmetrical and asymmetrical tooth stress fields under the same modular conditions follows. This leads to the formulation of a rule for similar modules governing variations of stress fields, depending on the pressure angle of the nonactive side. Finally a procedure allowing for calculations for percentage reductions of asymmetrical tooth modules with respect to corresponding symmetrical teeth, maximum ideal stress being equal, is proposed. Then the consequent reductions in size and weight of asymmetrical teeth are assessed.
The traditional way of controlling the quality of hypoid gears' tooth flank form is to check the tooth flank contact patterns. But it is not easy to exactly judge the tooth flank form quality by the contact pattern. In recent years, it has become possible to accurately measure the tooth flank form of hypoid gears by the point-to-point measuring method and the scanning measuring method. But the uses of measured data of the tooth flank form for hypoid gears have not yet been well developed in comparison with cylindrical involute gears. In this paper, the tooth flank form measurement of generated face-milled gears, face-hobbed gears and formulate/generated gears are reported. The authors discuss the advantages and disadvantages of scanning and point-to-point measuring of 3-D tooth flank forms of hypoid gears and introduce some examples of uses of measured data for high-quality production and performance prediction.
News Items About ISO
1 ISO Releases New Gear Standards (April 5, 2006)
ISO's Technical Committee on Gears, comprised of a multi-national delegation, published several new standards, including: ISO 6336... Read News
2 Sandvik Coromant Launches ISO S Insert Program (October 19, 2010)
Sandvik Coromant recently launched more than 300 inserts in a new series of optimized ISO S turning geometries with easy-to-choose guidel... Read News
3 ABA-PGT Awarded ISO TS 16949 Automotive Certification (March 29, 2011)
ABA-PGT Inc., a producer of high precision tooling and precision-molded plastic gears, has been awarded the ISO TS 16949 Automotive Certi... Read News
4 KISSsoft Releases Newest Version of ISO/CD TR 15144 (May 12, 2010)
In the hitherto existing draft ISO/CD TR 6336-7, the information for the definition of the permissible specific lubri... Read News
5 Philadelphia Gear Completes ISO-9001 for All Five Regional Service Centers (April 13, 2005)
Philadelphia Gear Corp., a full-service provider of gearing and power transmission solutions, has completed ISO-9001 (2000 standard) cert... Read News
6 Kleiss Gears Accredited to ISO 9001 (March 10, 2006)
Kleiss Gears announced its recent accreditation to ISO 9001. According to Rod Kleiss, company president, the certification was necessa... Read News
7 Paulo Products Upgrades to ISO TS 16949: 2002 (April 18, 2006)
The St Louis, MO facility of Paulo Products Company has successfully passed the upgrade audit and has been awarded accreditation to ISO/T... Read News
8 Penta Gear Receives ISO17025 Accreditation for Technical Competence in Calibration (January 4, 2018)
In October, A2LA labs accredited Penta Gear Metrology ISO17025 for technical competence in the field of calibration. Penta Gear President... Read News
9 Star Cutter Company Receives ISO Registration (January 11, 2013)
Star SU recently announced that Star Cutter has received a Certificate of Registration for ISO-9001:2008. Star Cutter was registered to t... Read News
10 Inductoheat Receives ISO 9001:2008 Certification (March 22, 2010)
Inductoheat Inc. recently received its ISO 9001:2008 certification for induction heating coils, power supplies and ancillary equip... Read News
11 Schafer Precision Machining Receives ISO Certification (October 19, 2011)
Schafer Precision Machining in Fort Wayne, a division of Schafer Gear Works, recently received ISO 9001:2008 certification for the manufa... Read News
12 Philadelphia Gear Completes ISO-9001 Certification (January 5, 2005)
The Lynwood, CA facility of Philadelphia Gear Corp. has completed ISO-9001 (2000 standard) for quality management system standards. Ac... Read News
13 Timken Power Systems Facility Achieves ISO 9001:2008 Certification (March 4, 2015)
The Timken Company recently announced its power systems service facility in Princeton, WV, has earned ISO 9001:2008 Quality Manageme... Read News
14 Paulo Products Accredited to ISO/TS 16949:2002 (February 9, 2005)
The Murfreesboro, TN, facility of Paulo Products Co. passed the upgrade audit for accreditation to ISO/TS 16949:2002. The standard req... Read News
15 Klϋber Lubrication Receives ISO 21469 Certification (July 23, 2014)
Klϋber Lubrication, a worldwide manufacturer of specialty lubricants, has received the National Sanitation Foundation (NSF) ISO 2146... Read News
16 Estudio Pina Certified to ISO 9001: 2000 (January 31, 2005)
Estudio Pina has received its ISO 9001:2000 certification for the scope of technical assistance services in mechanical gear drives and me... Read News
17 Columbia Gear Awarded ISO/TS 16949?2002 Certification (December 6, 2003)
Columbia Gear Co. was awarded ISO/TS 16949?2002 certification. The standard was created to meet the quality requirement for automotiv... Read News
18 ISO Workgroup 13 Takes Place at KISSsoft AG (May 30, 2013)
The last meeting of the ISO Workgroup 13 on bevel gear calculation took place on the 23rd and 24th of May 2013 at the KISSsoft AG, in Swi... Read News
19 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
20 Broaching Machine Specialties Completes ISO Registration (March 2, 2005)
Broaching Machine Specialties of Novi, MI, was awared a certificate of registration for ISO 9001:2000 conformance for the design, manufac... Read News
21 Bison Appoints New Vice President of Sales and Marketing (April 2, 2006)
Bison Gear and Engineering announced that John Morehead has been appointed vice president of sales and marketing. Morehead was previo... Read News
22 Bison Gear CEO Appointed to National Science Board Commission (April 7, 2006)
Ron Bullock, chairman and CEO of Bison Gear and Engineering, has been appointed as a member of the Commission on 21st Century Education i... Read News
23 New Gearmotor from Bison Gear (April 16, 2004)
The 562 Series hollow-shaft gearmotor from Bison Gear has an increased center distance and greater clearance for wider faced gear shafts.... Read News
24 New Vibration Mounts from AAC Feature Finger-Flex Ring and Bushing Isolators (April 2, 2006)
The new V10Z 4 Series of vibration mounts from Advanced Antivibration Components feature unique "Finger-Flex" isolators which are designe... Read News
25 Bison Gears Hollow Shaft Gearmotor Doubles Continuous Torque Ratings (March 10, 2006)
Bison Gears new 562 series hollow shaft gearmotor offers increased low speed center distance coupled with greater clearance for wid... Read News
26 Bison Gear, Armature Electric Partner for Power Transmission Distribution (April 13, 2005)
Bison Gear and Engineering announced the addition of Armature Electric Ltd. as the Bison power transmission distributor for western Canad... Read News
27 New Gearmotors from Bison Gear (March 18, 2005)
The new parallel shaft AC gearmotors from Bison Gear & Engineering are available in five gear ratios ranging from 5.8:1 to 42.8:1. Th... Read News
28 DSMs Stanyl Precison Gears Help Disabled Patients Drive Independently (April 11, 2006)
Precision gears made out of Stanyl, a high-performance polyamide 46 (PA46) resin from DSM Engineering Plastics, help keeps the Joyster mo... Read News
29 Bison Gear Awarded $100,000 Grant (April 19, 2005)
The National Science Foundation has awarded a $100,000 grant to Bison Gear and Engineering to determine the feasibility of a breakthrough... Read News
30 Bison Gear Appoints New Preident, Executive Vice President (January 10, 2006)
Larry Kujovich was appointed president of Bison Gear and Engineering. The company also promoted George Thomas to executive vice president... Read News
31 Bison Gears Adds Custom AC Motors (March 15, 2006)
Bison Gear and Engineering plans to begin manufacturing their own line of AC motors in their St. Charles, IL, facility beginning in April... Read News
32 GM Plans $5.6 Billion Sale of Allison Transmission (June 28, 2007)
General Motors Corp. announced on June 28 it will sell its Allison Transmission commercial and military business to The Carlyle Group&nbs... Read News
33 Delta Receives ISO 17025:2005 Designation (April 18, 2013)
Delta Inspection, the newest company of the Delta Family of Companies, located in Livonia, Michigan is pleased to announce that it has be... Read News
34 Rotek Receives ISO Certifications (December 13, 2012)
Rotek Incorporated, a company involved in forging seamless rolled steel rings and the design, development and production of slewing beari... Read News
35 KISSsoft Offers Load Distribution According to ISO 6336 Annex E (September 4, 2012)
The load distribution in the axial direction of cylindrical gears can be calculated very efficiently according to the calculation method ... Read News
36 Novak First Woman Elected to Bison Gear Board of Directors (February 27, 2015)
Bison Gear and Engineering is pleased to announce the election of Laurel Novak to their Board of Directors. Novak will represent th... Read News
37 Ti-Coating Announces its Tinalox SN2 Coating for Applications in All ISO Materials (March 27, 2015)
Ti-Coating announces its new PVD coating Tinalox SN2 for indexable carbide tooling. The Tialn-based coating provides excellent machining ... Read News
38 Bodycote Hot Isostatic Pressing Location Earns Highest Level of Nadcap Accreditation (May 16, 2017)
Bodycote has announced that its Camas, Washington Hot Isostatic Pressing (HIP) location earned the highest level of Nadcap accreditation ... Read News
39 AGMA Awards Maiuri with the Technical Divison Executive Committee Award (November 14, 2016)
It has been a tradition of AGMA’s Technical Division to acknowledge the outstanding contributions of individual committee members w... Read News
40 Sandvik Coromant Introduces Grade for ISO H05 and H15 Applications (October 7, 2016)
To help manufacturers enjoy benefits such as reduced cycle times and greater tool life when performing hard part turning, Sandvik Coroman... Read News
41 Allison Transmission Purchases Cell from C & B Machinery (April 10, 2012)
Allison Transmission, which manufactures commercial-duty automatic transmissions and hybrid propulsion systems for truck and off-road veh... Read News
42 C & B Awarded Allison Transmission Order (February 3, 2011)
C & B Machinery has been awarded an order by Allison Transmission to build a "Flexible" double disc grinding cell for its C... Read News
43 Bison Gear Wins Community Leadership Award (June 12, 2007)
Bison Gear & Engineering Corp. will receive The Business Leadership Award from the River Valley Workforce Investment Board on June... Read News
44 Bison Gear Institutes Skilled Workforce Initiative (May 24, 2007)
Bison Gear & Engineering is collaborating with other manufacturing, governmental and educational institutions to remedy the shortage of q... Read News
45 Bison Gear Appoints New President (January 9, 2007)
Bison Gear & Engineering Corp. announced the appointment of Martin Swarbrick as president and Chief Operating Officer. Most recently,... Read News
46 Bison Gear Named One of Chicago's Best and Brightest Companies (June 20, 2007)
Electric motor manufacturer Bison Gear & Engineering Corp. has been selected one of Chicago's 101 Best and Brightest Companies to Work Fo... Read News
47 Bison VWDIR Line Expands (December 2, 2008)
A right-angle AC gearmotor in six standard models is the latest product released in the Von Weise Drop-In Replacement gearmotor line from... Read News
48 Sicmat Achieves ISO 14001 Certification (December 1, 2010)
Sicmat S.p.A., an Italian company with 70 years of experience in the field of machine tools for the automotive industry, as well as preci... Read News
49 Oliver Gear Earns ISO 9001-2008 Registration (September 10, 2010)
Sam Haines, president of Gear Motions, joins Mike Barron, vice president/general manager, and some of the Oliver Gear employee owners, up... Read News
50 Bison Gear Adds 46 Models to FlexTorq Line (October 6, 2009)
The FlexTorq line of gearmotors from Bison Gear and Engineering Corp. continues to grow with 46 models of the 562 Series of hollow shaft ... Read News
51 Bison Gear Introduces Line of AC Motors (April 12, 2006)
Bison Gear & Engineering introduced a new line of custom AC motors manufactured in their St. Charles, IL, facility. Motors will be ava... Read News