Fraunhofer Institute for Mechanics of Materials IWMDevelopment and optimization of solid-lubricated rolling bearings; determination of the optimal composition of a polymeric composite lubricant; design of a rolling bearing cage to enable controlled lubricant transfer; mechanistic understanding of the friction and transfer mechanisms of PTFE/PEEK composites.
Polytetrafluoroethylene lubrication of radial roller bearings: Control of lubricant transfer through cage design according to materials-specific requirements
Completed research project
Project description
The solid lubricant polytetrafluoroethylene (PTFE) is often used in low-load rolling contacts when the use of conventional liquid lubricants is ruled out due to operating conditions such as vacuum or high temperatures. For use in high-load rolling contacts, however, the strength of PTFE is no longer sufficient, and lifetime lubrication is no longer possible. In rolling bearings, a technical solution to compensate for PTFE loss is continuous relubrication, whereby PTFE reservoirs are installed in the rolling bearing cage and lubricant is gradually transferred to the rolling elements. In addition, the strength of PTFE can be increased by mixing it with the high-performance polymer PEEK.
As part of the project, the lubrication mechanisms of PTFE were investigated both experimentally (RWTH Aachen University) and by means of atomistic simulations (Fraunhofer IWM), and the feasibility of its use in roller bearings via a transfer film generated between the rolling elements and the cage was demonstrated. Furthermore, the use of a PTFE/PEEK composite drastically reduced lubricant consumption due to wear of the composite, as PTFE is anchored in the PEEK matrix and is therefore less easily removed from contact.
Work packages Fraunhofer IWM:
- Development of a simulation setup for solid-lubricated steel surfaces
- Simulative investigation of the friction, wear, and transfer mechanisms of PTFE and PTFE/PEEK
Transfer of project results to the following Fraunhofer IWM R&D services for companies:
- Development of customized force fields for atomistic simulations of solid-lubricated systems
- Clarification of friction mechanisms of polymeric solid lubricants as a basis for the mechanism-based substitution of fluorinated lubricant components
- Determination of ideal lubricant quantities as a compromise between lubricant consumption and friction reduction
