A meticulous friction torque model for a lubricated ball screw considering the surface roughness

This study proposes a meticulous friction torque model considering both the asperity interaction and fluid traction mechanisms in micro-scale physical analysis. The fractal theory is employed to characterize the surface roughness in the asperity interaction component. The modification factor is derived to describe the actual contact condition precisely. A dedicated friction coefficient is obtained by fitting experimental data, enabling an accurate characterization of the friction exhibited by the ball screw. The fluid traction component involves the formu-lation of the modified oil film thickness, achieved by subtracting a modification factor from 1. This model is validated through the experimental data and is more suitable for light to moderate working conditions, contributing to a better understanding and prediction of friction torque.