Peculiarities associated with testing polyetheretherketone (PEEK) in a model rolling contact

Polyetheretherketone (PEEK) was investigated using a modified version of the four-ball tester in which the upper forth ball was replaced by a cone in such a way that kinematics of the four-ball configuration were fully preserved. Rotation of the cone enforced orbiting and rolling of the ceramic balls around the polymer cup. The results produced some unexpected peculiarities in the wear of ceramic balls which, in principle, should not take place. It is postulated that the wear of ceramic balls was due to the viscoelastic nature of the PEEK.