AGMA goes back to its roots this fall by holding the Fall Technical Meeting (FTM) in Pittsburgh, Pennsylvania, on October 2–4. From a historic perspective, this event marks the 100th year of AGMA meetings where technical papers will be presented on the subject of gearing. The first technical papers were presented during the 1916 Annual Meeting, which also was held in Pittsburgh.
AGMA’s expertise in understanding the technical intricacies of power transmission and delivering timely solutions has been demonstrated by technical presentations and in the development of AGMA standards over the last century. The presentations at this year’s FTM promise to follow on this tradition by providing insight into current state-of-the-art research on the future of our industry and recommendations that are immediately actionable for our FTM attendees. This year, as an attendee, you will listen to 23 presentations arranged into five sessions: Manufacturing, Inspection, and Quality Control; Materials & Heat Treatment; Application and Design & Rating; Efficiency, Lubrication, Noise, and Vibration; and Gear Wear & Failure. You will have the opportunity to talk with the presenters who come from various sectors of the industry from across the globe.
For your review, we have provided the titles and shortened abstracts in this edition of Gear Solutions. Even if you are not an engineer, I encourage you to review these abstracts and attend this event. Within these presentations, so many of our members have found insights that they have taken back and implemented to save time in a production technique or tweak something for better efficiency.
Come hear about advanced engineering steels; new possibilities of modifications with the continuous generating grinding method; new synthetic lubricant formulations; a new approach to repair large industrial gears; new methods for designing and specifying gear teeth; and so much more.
In addition to the 23 presentations, AGMA has arranged for two special presentations. During Session 3, the chairperson of the Helical Gear Rating Committee will provide a status report on AGMA 925-BXX “Method to Predict Micropitting, Wear, and Scuffing.” Two years ago, AGMA formed a sub-committee to review and revise AGMA 925-A03, with the specific goal of adding a method to predict the risk of micropitting to the Information Sheet. This presentation will cover conclusions to date, proposed changes, and the status of the Information Sheet.
Our second special presentation will be included in Session 5. Norbert Haefke of FVA GmbH will present “Standardization Based on Innovations from the German Drive Technology Industry Network.”
Presenters will be coming from several countries and from a wide variety of work and research settings. There will be opportunities to ask questions at the end of each session, as well as opportunities for networking. Come discover how others in the industry are finding successes in techniques in our field. Make new connections. Gain insights into how others look at similar problems that you face.
I encourage you to attend this event. And I would also like to take a moment to thank our more than 50 reviewers who took time out of their busy schedules to assist AGMA in providing this robust lineup.
The 2016 Fall Technical Meeting will also be the backdrop for the AGMA centennial event that closes our centennial year. A reception, open to all, will take place on the evening of Monday, October 3. This event is included in the full registration for the FTM, but individual tickets are also available for $75 on www.agma.org.
AGMA Fall Technical Meeting — Presentation Lineup
Session 1 – Manufacturing, Inspection, and Quality Control
Efficient Hard Finishing of Asymmetric Tooth Profiles and Topological Modifications by Generating Grinding
Andreas Mehr, Liebherr-Verzahntechnik GmbH
New possibilities of modifications with the continuous generating grinding method will be presented, such as Deviation Free Topological grinding (DFT), Generated End Relief (GER), Noise Excitation Optimized modification (NEO), and hard finishing of asymmetric gears. The focus is on the explanation of the technical challenges, their solutions, and the principal function of the dressing and grinding processes.
The Whirling Process in a Company that Produces Worm Gear Drives
Massimiliano Turci, Eng, Studio Tecnico Turci
This paper looks at the benefits that can be realized with the introduction of a whirling machine into the worm gear manufacturing facility. The benefits include time and cost savings, especially in regard to the need for grinding, increased quality, and environmental considerations due to not needing cutting oils.
Worm Screws High-Speed Manufacturing
Jean-Laurent Feutren, Affolter Technologies SA
The conventional setup of a gear hobbing machine for the production of helical gears has the hob axis perpendicular (±30°) to the workpiece. This setup does not allow for conventional manufacturing of worm gears. To solve this problem, a high-speed method will be presented that reverses the axis between the workpiece and tool and utilizes a high-speed spindle (up to 16,000 rpm). This method can produce worm gears eight times faster than conventional methods.
Twist Control Grinding (TCG)
Walter Graf, Reishauer AG
This paper introduces the latest process developments for the hard finishing of gears in regards to controlling flank twist. Flank twist occurs as a matter of course when machining helical gears that feature lead modifications and is brought about by the geometries and kinematics inherent in the continuous generating grinding of helical gears. Controlling the flank twist on gears using twist control grinding (TCG), can either eliminate twist completely or introduce a counter-twist to counteract the deformation of gears under load.
Session 2 – Materials & Heat Treatment
Review of Microstructure and Properties of Non-Ferrous Alloys for Worm Application and Advantages of Centrifugally Cast Bi-Metal Gear Blanks
Giri Rajendran, MCC International
This paper reviews the microstructure and properties of tin bronze, manganese bronze, and aluminum bronze materials that make them suitable for specific worm gear applications. The advantages of centrifugally cast bi-metal gear blanks and some common causes of worm gear failures are discussed.
Pre-Nitriding: A Means of Significantly Increasing Carburizing Throughput
Thomas Hart, Seco/Warwick Corporation
Higher carburizing temperatures allow end users to use shorter cycle times and significantly increase production rates but can lead to grain growth. Pre-nitriding is a relatively new technology that addresses grain growth and allows carburizing end users to carburize at higher temperatures. Real-life case studies show how carburizing productivity has doubled, and sometimes tripled, using pre-nitriding.
Performance and Machining of Advanced Engineering Steels in Power Transmission Applications – Continued Developments
Lily Kamjou, MSc, Ovako AB
This paper discusses the potential gain for the power transmission industry by making use of the material properties of advanced engineering steels to support more demanding applications. Machining the advanced engineering steels is discussed based on a number of recent studies. All studies indicate that by optimizing machining parameters and tools, the productivity and efficiency of these processes can be maintained or even improved.
Gear Design Relevant Steel Cleanness Metrics
E. Buddy Damm, TimkenSteel Corporation
This paper describes the methods used to characterize premium quality clean steels through the use of statistics of extreme values (SEV) and the use of these data to perform gear design relevant engineering analysis of the potential for a gear failure due to bending fatigue in the root or flank. Literature evaluation, modeling results, and experimental results are presented in order to validate the approach.
Development of High-Hardness Cast Gears for High-Power Applications in the Mining Industry
Fabrice Wavelet, Ferry-Capitain
Multiple solutions are available to increase the transmissible power of girth gears, including using a larger module, increasing the gear diameter, enlarging the face width, and increasing the hardness of the base material. Base material hardness, the only parameter that is not limited by cutting machine size, is being increased to meet higher power needs. This paper will review the related design and manufacturing impact of the high-hardness gears needed to meet today’s industry demands.
Session 3 – Application and Design & Rating
Computerized Design of Straight Bevel Gears with Optimized Profiles for Forging, Molding, or 3D Printing
Alfonso Fuentes, Rochester Institute of Technology
Research will be presented on whether there is a reference profile that will yield the same advantages for bevel gears as the involute for cylindrical gears. The spherical involute and octoidal profiles will be studied, and the virtual generation of bevel gears with the different profiles will be developed and simulated using advanced tools such as tooth contact analysis and finite element analysis.
Contact Fatigue Characterization of Through-Hardened Steel for Low-Speed Applications Like Hoisting
Michel Octrue, CETIM
Lubrication by grease is often employed on open gears that transmit power at low speeds. The rating methods found in ISO 6336 have shown that ISO is very conservative for grease-lubricated, through-hardened steel gears running with case-hardened pinions, specifically when considering service life. Fatigue SN curves resulting from tests will be compared and discussed with values given in ISO and AGMA gear rating standards.
Determination of Load Distributions on Double Helical Geared Planetary Gearboxes
Tobias Schulze, DriveConcepts GmbH
The optimization and effective utilization of planetary gearbox designs require a detailed consideration of the loads on the gears. This paper presents a computer-aided calculation method that has been developed for planetary gearboxes with spur and helical gears and considers the most important influences on the load distribution. Using this information, a detailed load distribution is possible to reach the maximum capability of the gears.
Designing Very Strong Gear Teeth by Means of High-Pressure Angles
Rick Miller, Innovative Drive Solutions LLC
This paper will show a method of designing and specifying gear teeth with much higher bending and surface contact strength than that of conventional gear teeth. The primary means of achieving this is by specifying gear teeth with significantly higher pressure angles. This paper will show calculation procedures, mathematical solutions, and the theoretical background and equations to achieve this.
Session 4 – Efficiency, Lubrication, Noise, and Vibration
Impact of Surface Condition and Lubricant on Effective Gear Tooth Friction Coefficient
Aaron Isaacson, Gear Research Institute
Using a four-square, power re-circulating gear test rig with high-accuracy torque transducers, losses due to operating speed, surface roughness, and torque level, including two different lubricants, were compared. Measurements of the effective coefficient of friction at the gear tooth flanks are provided. This paper summarizes the results obtained.
Surface Structure Shift for Ground Bevel Gears
Sebastian Strunk, MSc, The Gleason Works
A process is presented that improves the excitation behavior of a ground bevel gear set by altering the surface structure of a generated member along the path of contact from slot to slot. This process addresses this objectionable harmonic excitation by influencing each axis position in each line of the axis position table with small predetermined or random amounts.
Developing an Energy-Efficient Industrial Gear Oil
Shubhamita Basu and Mr. Dan Wilkerson, The Lubrizol Corporation
This paper describes a laboratory test rig, test procedure, and results that are focused on quantifying increased operating efficiency with various synthetic lubricant formulations. Fluid evaluations were conducted in an industrial-scale worm gear efficiency rig. Operating under a wide range of speeds and loads, the rig produced sharp differentiation among fluids for their impact on power loss and operating temperature.
Analysis of Excitation Behavior of a Two-Stage Gearbox Based on a Validated Simulation Model
Marius Schroers, MSc, Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University
In order to reduce development and production costs of a gearbox, simulation models have been set up to predict the noise and vibration behavior of a gearbox before the prototype phase. A simulation model, verified by experimental results, is presented that is able to calculate the dynamic excitation behavior of a two-stage gearbox.
An Experimental and Analytical Comparison of the Noise Generated by Gears of Both Austempered Ductile Iron (ADI) and Steel
Donald Houser, The Ohio State University – Gear and Power Transmission Research Laboratory
Many have made claims concerning the relative noise performance of austempered ductile iron (ADI) versus steel as a gearing material. Predictions based on measured tooth topographies of the transmission error and “sum of forces” gear noise metrics show that the iron gears should be slightly quieter than the steel gears at loads beneath the transmission error optimization “notch” torque and slightly louder above this torque. This paper presents results from a systematic experimental study to ascertain these differences.
Session 5 – Gear Wear & Failure
Numerical Thermal 3D Model to Predict the Surface and Body Temperature of Spur and Helical Polymer Gears
Niranjan Raghuraman, MS, Romax Technology
Tooth surface wear is an important failure mode in plastic gears, and this is primarily caused by the surface temperature increasing to a value close to the melting point of the material. Thus, it is critical to compute the temperature of the gear pair in an accurate fashion. This paper will focus on the prediction of gear temperature of plastic gears using a numerical heat transfer model based on 3D finite difference method.
Influence of the Defect Size on the Tooth Root Load-Carrying Capacity
Jens Brimmers, MSc, Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University
Conventional calculation methods for the flank and tooth root load-carrying capacity are well-established, but models that consider the defect size on the tooth root strength have not yet been applied in fatigue models for gears. This paper will introduce a method for calculating the tooth root load-carrying capacity for gears while considering the influence of the defect size on the endurance fatigue strength of the tooth root.
Influence of Contact Conditions on the Onset of Micropitting in Rolling-Sliding Contacts Pertinent to Gear Applications
Amir Kadiric, Imperial College London
Recently, increased sliding has been one of the factors suggested to be responsible for the onset of micropitting, with the proposed underlying mechanism being the potential reduction of film thickness through increased sliding speed. This paper attempts to shed light on the tribological conditions that may lead to the onset of micropitting in lubricated, concentrated contacts representative of those occurring between gear teeth. In particular, the effect of slide-roll-ratio, surface roughness, and film thickness is studied.
Comparison of TIFF Load Capacity to Standardized Gear Failure Modes Using Boundary Conditions from an Efficient and Accurate Loaded Tooth Contact Analysis
Baydu Al, MEng, Smart Manufacturing Technology Ltd.
This study aims to improve the existing understanding of Tooth Interior Fatigue Fracture (TIFF) load capacity and compare calculated load capacity to the allowable loading conditions for bending and pitting fatigue failure, based on standard calculation procedures. Possible methods that could be used to mitigate TIFF risk are presented, and the effect of these methods on the performance with respect to the other failure modes are quantified.
A New Approach to Repair Large Industrial Gears Damaged by Surface Degradation – The Refurbishment Using the Modification of Both the Profile Shift Coefficient and the Pressure Angle
Horacio Albertini, HASA – Horacio Albertini Ltda
Superficial degradation of industrial gears, and a lack of approaches to repair them, have resulted in many gears being discarded prematurely. This paper presents a computer program and method for repairing industrial gears, enabled by the recent advances in multi-axis CNC machine centers and gear grinding, that considers the modification of both the profile shift coefficient and the pressure angle.
