Based on quasi-statics model of rolling bearing and the calcuation of its dynamic stiffness, considering the impact of speed, initial preload, thermal preload and oil thickness on bearing stiffness, bearing operating stiffness was obtained. Using bearing operating stiffness as spindle supporting stiffness, the parameterized FEM model of motorized spindles was established to analyze dynamic characteristics of spindles. Analysis results showed that those parameters are the key influence factors on dynamic characteristics for grinding motorized spindle, such as initial preload, suspending length of grinding wheel, spacing between front and rear bearings, front bearing set spacing and inner diameter of rotor.
