This report evaluates the design coefficients of friction for polytetrafluoroethylene (PTFE) bearings, identifying key influencing parameters through a literature review and a detailed test program. Seven parameters were studied: PTFE material and surface types, size, contact pressure, temperature, sliding speed, and surface contamination. The analysis presented in the report showed that unfilled dimpled lubricated PTFE and filled flat PTFE exhibited the lowest and highest coefficients of friction, respectively. The coefficients of friction for unfilled flat and filled dimpled PTFE fell in between. The study found that coefficients of friction increased with higher sliding speeds and surface contamination but decreased with increased contact pressure. No consistent changes in the coefficients were observed with variations in specimen size or at low temperatures. Notably, surface contamination drastically increased friction coefficients—light dust levels increased friction tenfold, while heavier contamination prevented sliding altogether. Based on these findings, updated design coefficients of friction are proposed for the four main PTFE bearing types: flat (both unfilled and filled) and dimpled lubricated (both unfilled and filled). The report also discusses various preventative measures and underscores the importance of regular maintenance and the adoption of protective strategies to enhance bearing longevity and functionality.Report number: cmr 24-005
Published: June 2024
Project number: TR202204
Authors: Saeed Nejad, Jonathan C. McGormley
Performing organization: Wiss, Janney, Elstner Associates, Inc. (WJE)
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.