New Tribotester For Polymeric Materials

Polymer friction and wear play an increasing role in manufacturing of machine parts. The friction between plastic parts cannot be characterised by one single coefficient as almost all internal and external parameters have significant impact on the frictional properties. To be able to predict the friction between polymers a tribotester has been developed capable of handling polymer contacts and polymer-metal combinations. The apparatus can be set to measure friction and wear between test specimens described in the ASTM standard D3702 and as a pin-on-disk tester. The novelty of the tribotester is that the test conditions can be varied transiently during a test period. The varied test parameters are: • Sliding speed and acceleration by electric servo motor. • Contact pressure as a step motor moves a dead weight. • Temperature and relative humidity as the tester can be located in an acclimatised chamber. The monitored outputs from the tribotester are the coefficient of friction and the wear rate. A friction and wear test on this tribotester is a selected period of time where the polymer specimens are subjected to variations of several of the above mentioned parameters. How the test period is set up depends on the later use of the polymers in constructions. A few preliminary results from the tribotester are analysed.