Tribological performance of bronze-filled PTFE facings for machine tool slideways

Abstract The friction and wear behaviour of bronze-filled PTFE facings against cast iron has been investigated under dry conditions in the laboratory. The work shows that the surface of the PTFE composite becomes enriched with bronze particles during sliding, owing to the preferential wear of the PTFE matrix. This contributes to the improved wear resistance of the composite, since the particles block the slip of the PTFE lamellae. The results also indicate that the onset of equilibrium wear after running-in is due to the development of a continuous PTFE transfer film on the cast iron counterface which shields the cast iron from further chemical adhesion and presents a much less aggressive surface to the PTFE counterface. A load-dependent transition from mild to severe wear was found at 54 N and occurred whether the PTFE was used as the flat plate or the pin. Failure of the PTFE facing occurred catastrophically owing to fracture in the adhesive with the failure thickness and time both decreasing with increasing load.