A Comparison of the Wear of Cross-Linked Polyethylene against Itself with the Wear of Ultra-High Molecular Weight Polyethylene against Itself

Wear tests were carried out on reciprocating pin-on-plate machines which had pins loaded at 10 N and 40 N. The materials tested were irradiated cross-linked polyethylene sliding against itself, irradiated ultra-high molecular weight polyethylene sliding against itself and non-irradiated ultra-high molecular weight polyethylene sliding against itself. After 153.5 km of sliding, the non-irradiated ultrahigh molecular weight polyethylene plates and pins showed mean wear factors under 10 N loads, or a nominal contact stress of 0.51 MPa, of 84.0 × 10−⁶ mm³/N m for the plates and 81.3 × 10−⁶ mm³/N m for the pins. Under 40 N loads, or a nominal contact stress of 2.04 MPa, the non-irradiated ultra-high molecular weight polyethylene pins sheared at 22.3 km. At the last measurement point prior to this failure, 19.1 km, wear factors of 158 × 10−⁶mm³/N m for the plates and 85.0 × 10−⁶ mm³/N m for the pins had been measured. After 152.8 km, the irradiated ultra-high molecular weight polyethylene plates and pins showed mean wear factors under 10 N loads of 59.8 × 10−⁶ mm³/N m for the plates and 31.1 × 10−⁶ mm³/N m for the pins. In contrast, after 150.2 km, a mean wear factor of 0.72 × 10−⁶ mm³/N m was found for the irradiated cross-linked polyethylene plates compared with 0.053 × 10−⁶ mm³/N m for the irradiated cross-linked polyethylene pins.