Prognostic experiment for ball screw preload loss of machine tool through the Hilbert-Huang transform and multiscale entropy method

This paper attempts to detect and predict the preload loss and life time of the ball screw demands in the machine tool industry. Loss of preload leads to a lower natural frequency and the onset of the nonlinear spring characteristics of the ball screw. Such problems result in rapid downtime in the manufacturing process and gradually undetermined positioning errors. In this paper the preload features are extracted and discriminated using the Hilbert-Huang Transform (HHT) and Multiscale entropy (MSE) method. The starting torque and consecutive quasi steady state constant currents of the machine tool feeding table are conducted experimentally. The test results show the prognostic status of ball screw preload loss can be envisaged by the proposed methodology.