Design of a tribotester for evaluation of polymer components under static and dynamic sliding conditions

Abstract

Abstract

Coefficients of friction and wear lifetime for machine elements are usually estimated from pin-on-disc tests under fixed test conditions. The experimental design of a tribotester with variable sliding path, dynamically changing normal loads, and sliding velocities is presented in this paper together with a preliminary evaluation of sliding properties for engineering polymers. The design of a dynamic loading mechanism and control of the sliding motion are detailed. The importance of dynamic testing is illustrated for polyamides and polyacetals under pure, internally lubricated and glass fibre-reinforced conditions. Dynamic tests induce lower friction compared with static tests because of influences of visco-elastic deformation, inertia forces, and possibly molecular orientation on the sliding surface. Internal lubricants efficiently reduce friction and wear both under static and dynamic conditions. Glass fibres more effectively reduce wear rates on dynamic tests indicating different wear debris mobility in the interface.