Bearing preload optimization for machine tool spindle by the influencing multiple parameters on the bearing performance

The bearing preload plays an important role on the bearing performance, particularly the important characteristics of the bearing include bearing temperature increases, the bearing fatigue life, and ball skidding. Generally, the bearing preload contains the initial bearing preload and the thermal-induced bearing preload. Moreover, the bearing performance is closely related to machine tool accuracy. Obtaining an optimal bearing preload can improve the spindle work accuracy of machine tools. A method for determining optimal bearing preload over a wide range of speeds is given in this article. The method is based on the aforementioned factors that affect bearing performance, synthetically considering the initial preload and thermal-induced bearing preload, and it is verified both experimentally and with simulations. The results show that there is a minimum bearing preload value for avoiding the bearing ball skidding; the bearing temperature rise more than 30°C can be hardly achieved in the normal speed range, the fatigue life decides the biggest bearing preload; and the method is applicable to machine tool spindle usage.