Experimental study on the interface topography evolution and vibration monitoring in thrust ball bearings induced by contamination

Rolling bearings operating in harsh environments are extremely exposed to the risk of exogenous dust or wear debris particles, so there is a strong need to investigate the effects of particulate contamination on bearing operation and to identify problems early. The lubricated oil containing silica particles of various sizes and concentrations are prepared and introduced into thrust ball bearings to replicate the severe operating conditions. Vibration and acoustic emission (AE) signals were measured by accelerometer and AE sensor in a thrust ball bearing test rig. The experimental bearing raceway was observed by scanning electron microscope (SEM) and confocal laser scanning microscopy, and the evolution of the surface topography was analyzed to probe the wear mechanism. The results show that the most severe wear areas occur at the bottom of the bearing raceway, and its degree of wear is significantly influenced by the size and concentration of the silica particles. As the experimental time increases, the raceway surface undergoes an accelerated wear process originating from slight dimples, which leads to bearing failure. Furthermore, the introduction of particles into the lubricant increases surface root mean square (RMS) roughness, vibration and acoustic emission for different experimental durations. The vibration and AE signals are affected by a combination of solid particles and surface wear. The measured monitoring results can provide valuable information about the damage morphologies and subsequently about the state of the bearing during operation.