Abstract
Bearings used in demanding applications, such as wind turbines, pulverizers & grinding mills used in mining, rolling mills, coal pulverizing bowl mills etc., experience dynamic loads, torque reversals, varying speeds and boundary lubrication conditions. Because of these demanding application conditions, some bearings used in these applications are known to get damaged prematurely. Analysis of the prematurely damaged bearings showed cracks along the rolling contact line on the raceway surface. Metallographic investigations on the damaged bearings showed cracks in the subsurface regions and white etching matter along the cracks (called white etching cracks).
In this presentation, by presenting the results from differently tested and damaged bearings, we demonstrate the mechanisms and root causes behind the cracking along the rolling contact line and subsurface cracking. In addition, mechanism for white etching matter generation along the cracks is explained. Based on the explained mechanisms and the root causes, concepts behind crack resisting bearings will be shown. In addition, role of bearing steels’ microstructure and heat treat processes will be explained.