Testing P/M materials for high loading gear applications

Abstract

Details of a commercial rolling contact fatigue test bench are given; its design permits the evaluation of the rolling contact fatigue behavior of different materials, and makes it suitable for testing porous materials. Without additional machining the original as-sintered surface is tested. Elastohydrodynamic lubrication is applied, which is essential for testing porous material under realistic service conditions. Using the test bench, material behavior under variable loading conditions can be studied, allowing the life-time calculation for a given load-time history. Following a brief overview of rolling contact fatigue, results obtained with the test bench on wrought, cast, and P/M materials are given and analysed. The change from open to closed porosity in sintered steel influences significantly endurance limit and this impacts the development of new, high loading structural parts such as planetary gears and camshaft lobes.