A study was then conducted on actual gears having an isotropic superfinish. This study showed isotropic superfinishing technology increased a gear’s resistance to contact fatigue by a factor of three, and increased bending fatigue resistance by at least 10 percent. [2] This increase in gear performance translates to reduced operation and sustainment costs, and also offers the potential for weight reduction in new transmission designs.

The present paper will discuss an additional study which is underway to determine and compare the scuffing resistance of isotropic superfinished aerospace gears to that of baseline ground gears. Sample gears were made from case carburized SAE 9310. These tests were conducted using a method that progressively increases lubricant temperature until scuffing occurs, rather than the traditional load increasing method used in FZG testing rigs. The results of the current testing reveals that isotropic superfinished SAE 9310 specimens show at least a 40° F higher lubricant temperature at the point of scuffing compared to as-ground baseline gears. Based on these results and the previous studies, it was concluded that this isotropic superfinishing technology should be incorporated in all future aerospace gear designs. A later paper will report on similar scuffing testing performed on AMS 6308 gears due to run-outs achieved by both the baseline and isotropic superfinished samples during the current procedure.

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