Mechanisms of Surface Initiated Flaking and Long Life Technology of Rolling Bearings by Improving the Rolling Elements

摘要

The surface initiated flaking of rolling bearings occurs under poor lubrication. The bearing life with surface initiated flaking is sometimes shorter than calculated life. The mechanisms of surface initiated flaking, however, has not been fully understood. It was obvious that tangential force had a significant role on surface initiated flaking, and the increase in surface roughness of rolling elements causes the increase of tangential force acting on the raceway surface and reduces bearing fatigue life. This indicates that the bearing life can be extended by giving the rolling elements the superior durability against surface feature degradation. Based on the method described above, we developed the new material for rolling element with higher surface hardness produced by high nitride precipitates, which prevent the increase in surface roughness. It was demonstrated that the bearings installed rolling elements made of developed materials had superior life by 6206 bearing tests, i.e. further life extension and downsizing of rolling bearings can be achieved only by use the developed material for rolling elements.