Early failure analysis of automobile generator bearing

Abstract

“White Structure Flaking” (WSF) is an early subsurface type of spalling that often occurs in bearings of automotive components. The investigation into WSF in automotive generator bearings involves analyzing returned failure bearings as well as conducting fatigue life tests for hydrogen-charged bearings. Through various analytical methods, it has been ascertained that the degradation of the surface lubrication state caused by electric current and frequent acceleration or deceleration is the primary factor leading to the generation of hydrogen from the grease, consequentially resulting in the formation of WSF. The study examined the occurrence time of WSF in hydrogen-charged bearings through fatigue testing, and the hydrogen critical threshold for inducing WSF is 1 ppm. Generally, as the hydrogen content rises, WSF is more likely to occur earlier. However, if the hydrogen content exceeds 1.5 ppm, the occurrence time does not increase rapidly with an increase in hydrogen content.