A machine for fretting wear testing of plasma surface modified materials

Microscopic damage caused by fretting wear is of significant concern in many engineering applications. We report the design and performance of a versatile fretting wear testing machine that uses an electromagnetic actuator under closed-loop control to provide a constant slip amplitude over a wide frequency range. The machine is equipped with a mechanism that allows for gradual sample contact and precise relocation of the stylus. An innovative method for monitoring frictional forces during the course of a test is incorporated. The machine has been successfully applied to materials treated by three types of plasma surface modification: nitrogen ion implantation, thin film alloy deposition and diamond-like carbon film deposition.