Fatigue & pitting

Fatigue is the classical rolling-contact failure mode described in ISO 15243 and the basis of calculated bearing life. Repeated overrolling initiates micro-cracks below or at the raceway surface; when particles break out, small craters known as pitting appear, progressing to larger spalling. Symptoms include rising noise, vibration and temperature. ISO 15243 distinguishes subsurface-initiated fatigue under high load from surface-initiated fatigue caused by poor lubrication, contamination or overrolling of indentations. Countermeasures include adequate bearing sizing, clean mounting, effective sealing, a sufficient lubricant film, and early detection through condition monitoring to prevent consequential damage.