Further Understanding of Formation Mechanisms of Micropits and Microcracks on Precision-Bearing Raceway Surfaces Under Light Load Condition

Abstract

In this study, precision-bearing samples were tested on bearing test bench under light load condition for different time periods. Surface morphologies of damage bearing samples were characterized from two aspects (2D and 3D) by various methods. Numerous micropits can be observed on surfaces of raceways and steel balls. Combing with surface damage morphologies and thickness of oil films, it can be speculated that main formation mechanism of micropits is that the surface asperities puncture the oil film firstly and then squeezed into surface in contact with it. Potential effect of vibration during the formation process of micropits had been found by repetitive experiments on RCF test machine. Micropits can form more easily under higher vibration values. Surface microcracks can initiate and propagate with the synergistic effects of repeated plastic deformation and oxide-assisted.