Tribological investigations on metal-on-metal bearings during wear tests in a hip simulator according to ISO 14 242

Results of wear tests in the hip simulator E-sim are described. This simulator is able to carry out wear tests in accordance with ISO-standard 14 242. Volumetric and gravimetric wear rates of metal/polyethylene, ceramic/polyethylene and metal/metal-pairings were opposed. A wear test on a metal/metal-pairing of a surface replacement endoprosthesis with a diameter of 50 mm until 3 million cycles is specified in detail. Different measurement methods were used to characterize the wear behaviour. The 3-dimensional co-ordinate measurement allows the determination of the linear, volumetric and gravimetric wear as well as the determination of the worn area. Additional measurements of roundness were done and the test medium was analysed for wear particles. The 3-dimensional measurement was appropriate to satisfactorily show the extremely low amounts of wear for the metal/metal-pairing. After 3 million cycles a linear wear of 6,2 mum and a volumetric wear of 4,8 mm(3) were determined for the ball. For the socket these values were 7,5 mum respectively 3,2 mm(3).