Break-away friction of PTFE materials in lubricated conditions

This study investigates the tribological characteristics at initiation of sliding (break-away friction) of several polytetrafluoroethylene based materials. Four PTFE composites, pure PTFE, and white metal were tested in a reciprocating tribo-meter with the block on plate configuration against a steel counter-surface. Apparent contact pressure and oil temperature were varied from 1 to 8 MPa and 25 to 85 °C respectively. SEM investigations revealed wear patterns of the PTFE materials and the abrasive nature of hard fillers.Bronze filled, carbon filled, and pure PTFE were found to provide lower break-away friction and less variation over the course of testing and generally superior properties.

► Break-away friction with PTFE composites was significantly lower than Babbitt.
► Un filled PTFE provided the lowest break-away friction.
► Glass filled PTFE wore significantly on a steel counter-surface.
► PTFE break-away friction varied very little following an extended stop, Babbitt's increased dramatically.