Technical Committee Lubricants

Influence of lubricating grease composition and run-in procedures on the formation of anti-wear tribolayers in rolling bearings

In this research project the influence of different operating conditions and lubricant oils as well as greases on the buildup of tribological boundary layers during the run-in phase of rolling bearings was investigated. By using theoretical and microanalytical examination and the results of the experimental investigation fundamental propositions about the prerequisites for the buildup of effective boundary layers and their protective function were to be derived. The chosen model lubricants were tested with cylindrical roller thrust bearings under wear-critical conditions (FE8-wear test) concerning their wear protection and their ability to build up boundary layers. Most of the lubricants showed insufficient wear protection and boundary layer buildup. By the variation of the operating parameters bearing temperature, load and speed for all the tested lubricants a boundary layer formation was achieved. In the following, the influence of the boundary layers, which were formed out in the run-in processes, on the subsequent wear protection in the FE8-wear test was examined. For most of the otherwise unsuitable lubricants a very good wear protection was achieved following the respective run-in processes. Thus, run-in procedures with rolling bearings are suitable to achieve an increased operational reliability against wear, in dependence of the lubricant.

The IGF project (17280 N) of the research association DGMK Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V., Überseering 40, 22297 Hamburg was funded by the Federal Ministry for Economic Affairs and Energy via the AiF within the framework of the programme for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.