Roller bearings are important and common components, which assist in power transmission and the simultaneous decoupling of rotating and statically loaded machine components. Bearings need to be able to withstand high cyclic loadings, which means the surface of their inner rings must be smooth. To date, the effects of surface roughness and surface morphology on the lifespan of bearings under mixed friction conditions have not been analyzed in depth. This research project aims to address this by looking at the influence of different process-induced surface conditions of the inner rings of roller bearings. The bearings, manufactured by Zollern AG and INTERPRECISE Donath GmbH, and their fatigue behaviors are being investigated by MEGT (the Institute for Machine Elements, Gears and Transmissions). The Institute for Materials Science and Engineering (WKK) is contributing by examining the near-surface microstructure of the bearings’ inner rings using Scanning Electron Microscopy, as well as instrumented cyclic micro indentation tests (PhyBaLCHT) in high stress areas. The analyses are being performed in initial as well as fatigued states for each surface condition. The instrumented cyclic indentation tests enable local mechanical properties to be determined depending on the lifespan of the bearing. Combining the results of rolling fatigue tests and the analyses of surface morphologies, the project aims to produce a lifespan model, which establishes the surface quality necessary for the required service life of the bearing.

This project is conducted in collaboration with the Institute of Machine Elements, Gears and Transmissions,

the INTERPRECISE Donath GmbH, the ZF Friedrichshafen AG and the Zollern GmbH & Co. KG