Explicit modeling and investigation of friction forces in linear motion ball guides

Friction force of the linear motion ball guide (LMBG) with preload is important to predict the mechanical efficiency, thermal deformation, and stiffness variation in optimal design processes of the precision machinery. In this paper, an explicit friction force model of the LMBG with a two-point ball contact structure has been formulated in terms of the material and geometric parameters as well as the assembly and operating conditions. Contrary to the LMBG maker's model with accuracy 63%, the prediction accuracy over 90% is verified through experiments. It is confirmed that the friction force depends upon the ball size, conformity factors of the grooves, lubricant viscosity, and ball contact angles. Sliding and viscous frictions are significantly influenced by operating conditions as well.