Experimental analysis of the wear coefficient of double-nut ball screws

The wear coefficient is an important parameter that directly determines the wear rate of ball-raceway contact in ball screws and thus affects the degradation of the accuracy of ball screws and computer numerical control machine tools. However, few studies have experimentally studied the wear coefficient of ball screws. The present paper proposes a model for calculating the wear coefficient by considering the wear mechanism at the ball-raceway contact in ball screws. More importantly, a novel test method is implemented to measure the wear coefficient of seven double-nut ball screws, with total running of 48 million revolutions. Experimental results show two obvious wear stages and give wear coefficients that are several orders of magnitude lower than the empirical wear coefficient for continuous sliding friction between steel and steel, mainly owing to the special motion and wear mechanism of ball screws. The findings are important to the study of the degradation of the performance of ball screws due to wear.