The following study presents an experimental methodology, employed to characterize the NVH behavior of plastic gears NVH in application-like operating conditions, presenting guidelines for material selection in terms of optimal gear NVH. 

Overall developments and widespread public awareness of man-made climate change are transforming the way people think. The awareness has inspired a shift towards a more ecologically sustainable way of life. Driven by policymaking and technological innovation, ambitious efforts are underway to reduce greenhouse gas emissions to curb the rise in average temperatures. A key focus of these efforts is the mobility sector. 

The arrival of Gleason’s Hard Finishing Cell (HFC) in 2018 represented a paradigm shift in the way automotive transmission gears and gears for e-drives, could be produced in high volumes. Now, for the first time, 100 percent inspection of every gear, and every gear tooth was possible in-process, without impacting the high speeds at which these gears need to be hard finished. Identifying, and correcting for, conditions that create unacceptable noise behavior in these gears, on the fly, was finally a reality too.

This article introduces the process of polish grinding of gears. Improved surface quality increases the overall efficiency of gearboxes, resulting in reduced friction and torque loss, higher power density, and noise-optimized gears (lower NVH); all these factors are highly relevant, especially for electric drives. When Reishauer developed polish grinding in 2012, the process aimed to improve the efficiency of ICE engine transmissions, and the set goals were easy to achieve. Today, in 2023, the situation is dramatically different. While an ICE engine operates at around 3,000 rpm and supplies acoustic masking of the gear noise, EV drivetrains feature up to 20,000 rpm and offer no such masking.

A deep dive into the world of gear dynamics and gear noise has led many a mechanical engineer to Columbus, OH in search of the methods by which gear noise is measured and predicted as well as the techniques employed in gear noise and vibration reduction. Over the past 40+ years, about 2,550 engineers and technicians from 385+ companies have attended the Gear Dynamics and Gear Noise Short Course at The Ohio State University.

In modern automotive vehicles, gear noise becomes more and more of an issue. The main reason is the reduced masking noise of the engine, which vanishes completely in the case of an electric driveline. Improved gear quality unfortunately does not correlate with a better noise performance in any case. High gear quality makes sure that the gear flanks are inside tight tolerances and that all teeth are nearly identical. Even if the running behavior of such gear sets shows a very low sound pressure level, the noise perception for human ears may be annoying.

State of the Gear Industry Perspectives takes an in-depth look at the challenges and opportunities in gear manufacturing today and in the future. Our third installment online is an interview with Peter Wiedemann, managing director, Liebherr-Verzahntechnik GmbH and Scott Yoders, vice president sales, Liebherr Gear Technology, Inc. 

State of the Gear Industry Perspectives takes an in-depth look at the challenges and opportunities in gear manufacturing today and in the future. Our second installment online is an interview with Christof Gorgels, vice president, innovation and technology at Klingelnberg. 

State of the Gear Industry Perspectives takes an in-depth look at the challenges and opportunities in gear manufacturing today and in the future. Our first installment online is an interview with Udo Stolz, vice president of sales and marketing at Gleason Corporation.

In this latest edition, issue 9, of the GEARS inline Customer Magazine, Klingelnberg once again presents all sorts of trends and innovations from the world of gears. This time, the machine manufacturer focuses primarily on the hot topic of noise behavior and analysis.