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.