Influence of the Surface Morphology on Rolling Bearing Life Under Mixed Lubrication

In the existing design guidelines for rolling bearings, there is no direct evaluation of the influence of the surface morphology on the achievable fatigue life under mixed lubrication conditions. This work focuses on the influence of different surface finishing processes, i.e., fine grinding, rough grinding, and hard turning, on the fatigue life of inner rings of radial cylindrical roller bearings. In addition to fatigue life experiments at a four-bearing test rig, detailed analyses of the finishing-induced surface morphology as well as calculations of the stress condition caused by the different surface topographies were conducted. To characterize the surface morphology, the local mechanical properties were determined using cyclic micro-indentation tests and the residual stresses were measured by X-ray diffraction. For the stress calculations, a multiscale simulation composed of a multi-body model at the macro-level and a half-space contact model at the micro-level was used. The results obtained in fatigue life experiments, surface morphology characterization, and stress calculations were combined. From this for the hard turning a high potential to increase the fatigue life of roller bearings under mixed lubrication conditions was examined.