CONTACT FATIGUE EVALUATION OF SUPER HONED SPUR GEARS MADE OF AISI 4118 ALLOY STEEL

In this study, a set of gear pitting fatigue life experiments are conducted using super honed spur gear pairs made of AISI 4118 steel as test articles. The super honing process leads to surfaces that are significantly smoother than those of hard ground surfaces. As such, this process has been claimed to improve contact fatigue performance when compared to hard ground gears. Given the similarities in surface roughness amplitudes, super honing was also thought of having a pitting performance comparable to chemically polished gears. This study investigates the validity of these hypotheses by generating pitting fatigue data for super honed gears and comparing them to data available for ground and chemically polished gears from an earlier study by Franzen (2013). The results of this study show that super honing improved pitting fatigue lives by a factor of 1.5 to 2 compared to ground gears made of AISI 4118 material. Meanwhile, chemically polished gears have slightly longer lives than super honed gears of the same material.