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The benefits gained by superfinishing rear-axle hypoid gearsets are now well documented. Friction, wear and operating temperature are significantly reduced. The main impediment to commercially implementing this process, however, is that it increases manufacturing cost in terms of process speed, work in process and labor. The cost of superfinishing can be significantly reduced by employing a newly developed and fully automatable drag finishing process. The most primitive form of drag finishing occurred when Roman soldiers dragged their armor through sandy fields for obtaining a mirror-like appearance. Today's drag finisher, of course, is much more sophisticated. A circular turret is located above a circular bowl containing loose, ceramic media. Parts are attached to multiple rotating spindles on the turret, which in turn are immersed in the media in the bowl below, and are dragged through the media. This generates a high flow of media over the gearsets.

An Isotropic Superfinish (ISF) is produced by a patented chemically accelerated vibratory finishing process using non-abrasive media that is capable of surface finishing hundreds of parts per hour. Rolling/Sliding Contact Fatigue testing shows that this commercial technology virtually eliminates contact fatigue (pitting) in gear test specimens. Bending fatigue is also improved. Gears finished by this method will operate at higher power densities for much longer life cycles when compared to traditionally finished gears. Studies have confirmed that this process is metallurgically safe for both through hardened and carburized alloy steels. ISF can achieve an Ra < 0.038 μm (1.5 μin.) while maintaining an AGMA Q13 gear dimensions. Rolling/Sliding Contact Fatigue, single tooth bending fatigue, and rotating bending fatigue test results are presented.