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The geometry of the bevel gear is quite complicated to describe mathematically, and much of the overall surface topology of the tooth flank is dependent on the machine settings and cutting method employed. AGMA 929-A06 â€” Calculation of Bevel Gear Top Land and Guidance on Cutter Edge Radius â€” lays out a practical approach for predicting the approximate top-land thicknesses at certain points of interest â€” regardless of the exact machine settings that will generate the tooth form. The points of interest that AGMA 929-A06 address consist of toe, mean, heel, and point of involute lengthwise curvature. The following method expands upon the concepts described in AGMA 929-A06 to allow the user to calculate not only the top-land thickness, but the more general case as well, i.e. â€” normal tooth thickness anywhere along the face and profile of the bevel gear tooth. This method does not rely on any additional machine settings; only basic geometry of the cutter, blank, and teeth are required to calculate fairly accurate tooth thicknesses. The tooth thicknesses are then transformed into a point cloud describing both the convex and concave flanks in a global, Cartesian coordinate system. These points can be utilized in any modern computer-aided design software package to assist in the generation of a 3D solid model; all pertinent tooth macrogeometry can be closely simulated using this technique. A case study will be presented evaluating the accuracy of the point cloud data compared to a physical part.
When I first met the leaders of the gearing industry in April 2016 at AGMA's 100th Anniversary Celebration, I did my best imitation of Joe Namath, who famously predicted a Super Bowl victory for his New York Jets: I guaranteed we would reach our 101st year!
There is so much more to Gear Expo than gears or the machinery that makes them. That's because it takes much, much more to make a finished gear than even the most sophisticated machine. And it is exhibitors who are part of the "much, much, more" that are addressed in this article.
AGMA Sets Up Shop in Living Laboratory of the Midwest. Columbus, Ohio recently surpassed Indianapolis as the second largest city in the Midwest behind Chicago, according to the United States Census Bureau. This could change come the 2020 census, but there's no denying Buckeye Nation is going places.
Summer never lasts as long as you want it to. By the time you read this, you'll be well into the hazy, lazy days, and the season will be gone before you know it. That means you're running out of time to make plans to attend our industry's most important event. Of course, I'm talking about Gear Expo (October 24 - 26) and the AGMA Fall Technical Meeting (October 22 - 24), both of which will take place in Columbus, OH.
AGMA adds two new committees, Star Cutter Celebrates 90 years, plus other news from around the industry.
The complete Industry News section from the June 2017 issue of Gear Technology.
There are many benefits to attending Gear Expo, but if you're not taking advantage of the educational opportunities, you're missing out.
Faydor Litvin, 1914-2017; Michael Goldstein receives AGMA Distinguished Service Award.
Large, multi-segmented girth gears do not behave like the relatively compact, rigid, monolithic structures we typically envision when discussing gear manufacturing. Girth gears are very large, non-rigid structures that require special care during the machining of individual mating segments as well as the assembled gear blank itself.
Manufacturers focus on tool design, materials, coating, machine tool options and cutting parameters.
At the AGMA annual meeting last month, the association presented me with its Distinguished Service Award.
How do we educate the next generation of gear industry employees, and how do we train the ones we already have?
News from around the Industry
Bob Errichello retires from teaching, Siemens expands technical center, HBM Holdings acquires Schafer Industries, plus new hires and other industry news.
More than 100 years ago, gear manufacturers were facing a significant challenge from industry. The incredible advances in industrialization and transportation that occurred at the turn of the 20th century resulted in incredible growth for gear makers, but there were significant technical issues. "The lack of process and product standardization was a continuing problem in all U.S. industry. The lack of industry-wide gear standards meant there were no standard gear tooth sizes, ratings, quality definition or consistent manufacturing methods" (Celebrating 100 Years of Gearing, pg. 22).
No, not that president! I mean Matt Croson, the new president of the American Gear Manufacturers Association, who started in June and has been busy getting to know the gear industry and AGMA's members.
While the two have taught a variety of AGMA courses over the years, without question their most popular courses are Gear Failure Analysis (Errichello with longtime colleague Jane Muller) and Gearbox CSI: Forensic Analysis of Gear & Bearing Failures (Drago). Drago currently teaches Manufacturing & Inspection (with AGMA instructor Joseph W. Lenski, Jr.) and Gearbox System Design: The Rest of the Story - Everything but the Gears and Bearings (with AGMA instructor Steve Cymbala) as well.
A best practice in gear design is to limit the amount of backlash to a minimum value needed to accommodate manufacturing tolerances, misalignments, and deflections, in order to prevent the non-driving side of the teeth to make contact and rattle. Industry standards, such as ANSI/AGMA 2002 and DIN3967, provide reference values of minimum backlash to be used in the gear design. However, increased customers' expectations in vehicle noise eduction have pushed backlash and allowable manufacturing tolerances to even lower limits. This is especially true in the truck market, where engines are quieter because they run at lower speeds to improve fuel economy, but they quite often run at high torsional vibration levels. Furthermore, gear and shaft arrangements in truck transmissions have become more complex due to increased number of speeds and to improve efficiency. Determining the minimum amount of backlash is quite a challenge. This paper presents an investigation of minimum backlash values of helical gear teeth applied to a light-duty pickup truck transmission. An analytical model was developed to calculate backlash limits of each gear pair when not transmitting load, and thus susceptible to generate rattle noise, through different transmission power paths. A statistical approach (Monte Carlo) was used since a significant number of factors affect backlash, such as tooth thickness variation; center distance variation; lead; runout and pitch variations; bearing clearances; spline clearances; and shaft deflections and misalignments. Analytical results identified the critical gear pair, and power path, which was confirmed experimentally on a transmission. The approach presented in this paper can be useful to design gear pairs with a minimum amount of backlash, to prevent double flank contact and to help reduce rattle noise to lowest levels.
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.
This is a very exciting year for AGMA as the organization celebrates its 100-year anniversary. In addition to the anniversary, AGMA President Joe Franklin, jr., who has done an outstanding job at the helm of AGMA for the last 25 years, will retire, and we welcome in our new AGMA President, Matt Croson, who will lead us into the next 100 years. The centennial kicked off in October with a dinner at the AGMA Gear Expo in Detroit and will continue throughout 2016 with a number of exciting events scheduled to celebrate this milestone anniversary.
Lastest news from around the industry.
AGMA President Joe Franklin is stepping down after some 24 years on the job. He graciously took the time to answer some questions from Gear Technology Senior Editor Jack McGuinn regarding his tenure.
your life and in your professional career is an inflection point for you to take stock of where you came from and where you are going.
The 25th anniversary is the silver. The 50th is the gold. The 75th is the diamond. But what symbolizes the 100th?
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."
I would appreciate if you could assist with a gear failure (occurring) after just seven weeks in service, post installation. This driving gear wheel has been installed in a medium-speed engine with backlash present at four different positions; with additional backlash checked on the mating surfaces. All backlash was found within (OEM)-recommended values. Please note included photos - it seems that the crack has started at the root fillet. Any comments would be appreciated.
Gear Expo 2017 is your best opportunity to expand your knowledge, get answers to your technical questions and solve your toughest manufacturing challenges. The reason is quite simple. Gear Expo provides you with the greatest collection of gear expertise, know-how and experience you can find.
The definition is pretty straightforward: An association is an organization of persons having a common interest. Basically, it's a group that shares a purpose or mission that exists for the mutual advancement of its members.
Iâ€™ve just come back from the AGMA annual meeting in Napa, California, where I had a great time visiting with friends and colleagues in the gear industry. As always, the annual meeting was a great opportunity to network and meet with other AGMA members.
If you were offered an opportunity to spend quality time with leading experts in your field, where in-depth discussions and dialogues occurred on subjects that directly impacted your business, would you do it?
This paper relates specifically to gears that are finish ground and considered high speed per ANSI/AGMA 6011; meshing elements with PLVs (pitch line velocities) in excess of 35 m/s or rotational speeds greater than 4,500 rpm.
AGMA President Matt Croson explains how the association is here for members and the gear industry at large, providing information, resources, education and training -- even during the crisis.
In this edition of Arvin's Angle, Joe explains why training isn't an expense. It's an investment.
Welcome to a new era of Gear Technology magazine! AGMA is proud to add Gear Technology, Gear Technology India, Power Transmission Engineering, the Michael Goldstein Gear Technology Library and supporting websites and circulation under its umbrella.
You may have noticed a few changes around here. Most notably, the face on this page isn't the one you're used to seeing here. As you've probably heard by now, Michael Goldstein, founder and Publisher since 1984, has stepped back from his day-to-day duties and transferred the operation of Gear Technology, Power Transmission Engineering and Gear Technology India to the American Gear Manufacturers Association.
When I started Gear Technology more than 35 years ago, my intention was to create something of lasting value for the gear industry. It was a way of giving back to the industry that had been so good to me and my family.
Find the exhibitors you want to visit at the first-ever Motion+Power Technology Expo (formerly Gear Expo).
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.
When you go to MPT Expo, make sure to visit the exhibitors in our special advertising section!
In addition to hundreds of relevant suppliers, Motion+Power Technology Expo (Oct. 15-17 in Detroit) also offers many opportunities for learning.
There have always been plenty of reasons to attend Gear Expo. For decades, itâ€™s been the best place to see all of the technology, vendors and solutions in the gear industry, all under one roof. Now that it's the Motion + Power Technology Expo, it's even more true.
A reader asks: We are currently revising our gear standards and tolerances and a few questions with the new standard AGMA 2002-C16 have risen. Firstly, the way to calculate the tooth thickness tolerance seems to need a "manufacturing profile shift coefficient" that isn't specified in the standard; neither is another standard referred to for this coefficient. This tolerance on tooth thickness is needed later to calculate the span width as well as the pin diameter. Furthermore, there seems to be no tolerancing on the major and minor diameters of a gear.
The complete Industry News section from the June 2019 issue of Gear Technology./
A reader asks about ion-nitride finished shafts and the proper friction coefficient to be used for calculations.
A reader asks: I'd like to know about the different approaches and factors considered while determining the value of Ka in regards to the DIN 3990 and AGMA standards.
The world is changing. I've just returned from the AGMA Annual Meeting in Scottsdale, AZ. Like always, it was a great opportunity to visit with peers, colleagues, customers and competitors in the gear industry. But this year's event was far more than just a chance to reunite with old friends. No, this year's annual meeting was also a wake-up call.
It's time to catch up on the episodes of Revolutions that you might have missed.
As most of you know by now, the trade show formerly known as Gear Expo is now the Motion + Power Technology Expo. If you're a gear-industry veteran, you might be confused by this change. If you've been coming to the show for years - or exhibiting at it - you might even feel a little betrayed. But I'm here to tell you it's going to be alright.
Liebherr and Wenzel announce sales and service agreement; MPIF releases new powder metal standard; Gear Motions announces promotions; Profilator opens new factory and more gear industry news.
There are many different gear rating methods in use today, and they can give substantially different results for any given gearset. This paper will make it easy to understand the choices and the impact the choices have on gearbox design. Eight standards are included - AGMA 2001; AGMA 6011; AGMA 6013; ISO 6336; API 613; API 617; API 672; and API 677. (Click HERE for the Appendix to this article).
Will tariffs and quotas affect your ability to operate in the fourth quarter this year?
The complete industry news section from the June 2018 issue of Gear Technology.
A reader asks: We are currently revising our gear standards and tolerances, and a few problems with the new standard AGMA 2002-C16 have arisen. Firstly, the way to calculate the tooth thickness tolerance seems to need a "manufacturing profile shift coefficient" that isn't specified in the standard; neither is another standard referred to for this coefficient. This tolerance on tooth thickness is needed later to calculate the span width as well as the pin diameter. Furthermore, there seems to be no tolerancing on the major and minor diameters of a gear.
I have a query (regarding) calculated gear life values. I would like to understand for what % of gear failures the calculated life is valid? Is it 1-in-100 (1% failure, 99% reliability) or 1-in-one-thousand (0.1% failure)?
At most family reunions, everyone gets along, everyone puts on a good face, and everyone celebrates their togetherness. The AGMA annual convention held at the end of April was a lot like that.
A discussion of ISO and AGMA standards for gears, shafts and bearings, and the art of designing a gearbox that meets your requirements.
If you havenâ€™t already done so, you should make plans to attend Gear Expo in September. Itâ€™s a unique and important show, and you should take advantage of it.
How should we consider random helix angle errors fHÎ˛ and housing machining errors when calculating KHÎ˛? What is a reasonable approach?
What do glam and avant garde rock star Brian Eno, AGMA and Seattle Gear Works have in common? Admittedly, not much. But there is a connection of sorts.
Arlin Perry, president of Comer Industries, talks about his tenure as chairman of the AGMA Foundation and its role in supporting the industry.
October 5-8, 1986 AGMA Fall technical Conference & Gearing Exhibit September 17-19, 1986 Ohio State University Gear Noise Seminar November 11-13, 1986 SME Gear Processing and Manufacturing Clinic November 19-21, 1986 Seminar: Gear System Design for Minimum Noise
Herman Riccio, Chicago Gear Works President, to Retire; Gleason Opens MI Sales Office; American Pfauter hires Steve Peterson; plus AGMA's technical calendar for the Fall of 1984.
At a time when there are many pressures on the Gear Industry and its representative Association, the American Gear Manufacturers Association, it seems particularly appropriate that Gear Technology - The Journal of Gear Manufacturing appears. AGMA is particularly pleased to have the opportunity to write the first editorial for this magazine.
The AGMA Fall Technical Meeting provides an opportunity to share ideas with others on the design, analysis, manufacturing and application of gears, gear drives, and related products, as well as associated processes and procedures.
AGMA president Joe T. Franklin Jr. talks about how the AGMA Gear Expo has grown and changed since its beginnings as a table-top show in 1987.
AGMA Flexible Couplings committee chairman Glenn C. Pokrandt gives an update about standards and other documents under development.
Chairman Todd Praneis of Cotta Transmission describes the activities of AGMA's Enclosed Drives technical committee.
Gary A. Bish, director of product design technology for Horsburgh & Scott, discusses his role as chairman of the AGMA mill gearing committee.
A recap of the AGMA 2010 Fall Technical Meeting.
AGMA Chairman David Ballard discusses what it means to be an AGMA member.
Dr. Phil Terry, chairman of the AGMA Technical Division Executive Committee, talks about the standards-making process.
When you graduated from school and made your way into the world, you probably thought youâ€™d learned everything you needed to know to be successful. But those of us whoâ€™ve been out in the workforce for some time know that you never stop learning.
For the last few years, the market has been tough for the U.S. gear industry. That statement will cause no one any surprise. The debate is about what to do. One sure sign of this is the enormous attention Congress and the federal government are now placing on "competitiveness."
The world is full of acronyms. At work, the inbox reveals e-mails from the AWEA, SAE, MPIF and AMT. On the weekends, Saturday mornings are consumed by activities involving the AYSO, PTA, YMCA or DMV. Itâ€™s a struggle to determine what organization does what and why we should care in the first place.
Step forward now to help yourself and your industry.
The AGMA pavilion was a hot spot at October's PTC-Asia show in Shanghai, as evidenced by the intense quoting reported by exhibitors.
Despite the many things being done to promote manufacturing nationwide, there still remains an acute need for gear-specific training, remedial or otherwise.
Listing of papers to be presented and activities for the 2007 AGMA Fall Technical Meeting.
The organizers of Gear Expo 2007 promise to combine the most popular features of shows past with some innovations for this yearâ€™s attendees. By the time the show closes on October 10, the association hopes its targeted 175 exhibitors walk away with new insights leading to profitability and renewed contacts.
"One of the reasons AGMA has been successful over our 93-year history is that the associationâ€™s agenda, programs and activities reflect the voices of our members," says Joe T. Franklin, Jr., AGMA President.
Events from SME and AGMA, along with news from the gear industry.
Gear Technology talks with AGMA's president about the association and its role in the gear industry.
Industrial gear standards have been used to support reliability through the specification of requirements for design, manufacturing and verification. The consensus development of an international wind turbine gearbox standard is an example where gear products can be used in reliable mechanical systems today. This has been achieved through progressive changes in gear technology, gear design methods and the continual development and refinement of gearbox standards.
â€śThe gear marketplace is a global marketplace.â€ť Bill Bradley says it easily, with no special emphasis. The vice president of AGMAâ€™s technical division sees the statement as an obvious fact.
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.
A change has taken place within the industry that is going to have an enormous effect on the marketing, sales, and purchasing of gear manufacturing and related equipment. This change was the American Gear Manufacturers' Association, first biennial combination technical conference and machine tool minishow.
It is often easy for those outside of the gear industry to get the impression that nothing is changing in our business. After all, all illustrated bimonthly by the covers of this very journal the making of gears has been with us for centuries. However, nothing could be further from the truth.
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.
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.
So there is little chance that they need the same software to assist with their work. Gone are the days when companies wrote their own code and process engineers thumbed the same tattered reference book.
The face load factor is one of the most important items for a gear strength calculation. Current standards propose formulae for face load factor, but they are not always appropriate. AGMA 927 proposes a simpler and quicker algorithm that doesn't require a contact analysis calculation. This paper explains how this algorithm can be applied for gear rating procedures.
Charlie Fischer, VP Technical Division, retiring end of April
The AGMA/ABMA Annual Meeting took place April 10-12 in St. Petersburg, Florida. Between committee meetings, networking opportunities and social events, many individuals in the gear industry were presented awards.
In todayâ€™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.
The new chairman of the AGMA Technical Division Executive Committee explains what's involved in the process of developing technical standards at the AGMA.
It's nice to see old friends. It's also advantageous to make new ones. Gear Expo has always been a family reunion of sorts, but it's first and foremost an opportunity to show off the latest and greatest technologies that are impacting the gear industry today. With this in mind, Gear Technology recently spoke with those responsible for putting the Fall Technical Meeting (FTM) and Gear Expo 2013 together in Indianapolis.
"Gear Train" is a new Gear Technology section focusing on training and education in the gear industry. For the first installment, we've focused on AGMA's online and video training programs.
Another year, another AGMA Fall Technical Conference. But this is no ho-hum event. Not when every year, the conference attracts some of the greatest mechanical engineering minds on the planet, along with representatives of the worldâ€™s greatest manufacturing entities. And who knowsâ€”perhaps one day there will be an extraterrestrial contingentâ€”the science is that good. And all of it readily applicable to real-world manufacturing.
AGMA925â€“A03 scuffing risk predictions for a series of spur and helical gear sets of transmissions used in commercial vehicles ranging from SAE Class 3 through Class 8.
The major focus of the American Gear Manufacturers Association standards activity has been the accurate determination of a gearbox's ability to transmit a specified amount of power for a given amount of time. The need for a "level playing field" in the critical arena was one of the reasons the association was formed in the first place. Over the past 85 years, AGMA committees have spent countless hours "discussing" the best ways to calculate the rating of a gear set, often arguing vigorously over factors that varied the resulting answers by fractions of a percentage point. While all that "science" was being debated in test labs and conference rooms all over the country, out industry's customers were conducting their own experiments through the daily operation of gear-driven equipment of all types.
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 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.
AGMA introduced ANSI/AGMA 2015â€“2â€“A06â€” Accuracy Classification System: Radial System for Cylindrical Gears, in 2006 as the first major rewrite of the double-flank accuracy standard in over 18 years. This document explains concerns related to the use of ANSI/AGMA 2015â€“2â€“A06 as an accuracy classification system and recommends a revised system that can be of more service to the gearing industry.
The wind turbine industry has been plagued with gearbox failures, which cause repair costs, legal expenses, lost energy production and environmental pollution.
Who wants or needs technical details about gearing? Who cares about it? Three out of every four people who are reading this magazine make up at least 75% of those who have an interest in the subject. The members of AGMA, EUROTRANS, JGMA and JSIM have an interest. All the people attending the Gear Expo in Detroit have an interest. Clearly, however, the people with the most pressing interest in our industry are our customers, the end users of gear products. The unfortunate reality, though, is that in many cases, these customers don't even know that's what they want.
Long-time readers of these pages will know that I have always felt strongly about the subject of professional education. There's nothing more important for an individual's career development than keeping up with current technology. likewise, there's nothing more important that a company can do for itself and it employees than seeing to it they have the professional education they need. Giving people the educational tools they need to do their jobs is a necessary ingredient for success.
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.
AGMA and members of the Metal Powder Industries Federation (MPIF) are three years into a joint project to develop specifications and an information sheet on rating powder metal gears. According to committee vice chairman Glen A. Moore of Burgess-Norton Mfg. Co., the first phase of the project, the publication of AGMA Standard "6009-AXX, Specifications for Powder Metallurgy Gears," should be completed in late 1996 or early 1997.
AGMA has an excellent Training School for Gear Manufacturing. It's a great product providing a great service to the gear industry. Thus far we've educated 117 employees from 71 companies; students range from new hires with no experience to company presidents. Essentially every class since December, 1992, has been sold out.
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.
A few months ago at the AGMA management seminar, I was surprised by the feverish note taking that went on at a presentation on marketing. The sight reminded me that while many of us in the gear industry are good engineers, designers, and mangers, we are often not as familiar - or comfortable - with less concrete concepts, such as marketing.
Five years of effort by AGMA came to fruition in January with the publishing of a report from the Department of Commerce. This "National Security Assessment of the U.S. Gear Industry" indicates that if serious measures are not taken, the gear industry's future is in jeopardy. It also sets the tone for confronting major challenges now looming large in our industry.
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.
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.
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.
Writing about additive manufacturing (AM) and the 3-D printing of gears is somewhat akin to publishing an updated dictionary. A new edition dictionary is literally already out of date before it hits Amazon's or your local bookseller's shelves. New words are coined and definitions are updated constantly. So it is with AM: The technology is evolving so quickly that technical papers and other sources of AM information require constant revision.