Method for friction estimation in reciprocating wear tests

A method is described by which the coefficient of friction was determined using a linear reciprocating wear testing machine with spherical metal indenters articulating on flat UHMWPE samples and deionized and distilled water lubrication. A characteristic periodic pattern in the friction behaviour was observed. The coefficient of friction was computed by calculating the average of 30 points about the midpoint between reversals and using the average of three cycles. Variability between tests was equivalent to that obtained between stations but was considerably higher than that obtained between cycles. The coefficient of friction could reliably be estimated using this method with a standard deviation of 0.005.