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 formulation 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.