Evaluation of Dynamic Characteristics of Oil-Air Spindle Using Contact-Less Dynamic Spindle Tests

This paper presents the effects of setting and operating conditions on the performance of an oil-air spindle. While several studies have explored the dynamic stiffness of running spindles, few have focused on analyzing these spindles to their operational states. This paper introduces a method for electromagnetic excitation and dynamic compliance measurement to characterize the dynamic behavior of an oil-air spindle in response to an applied excitation force. The dynamic compliance of the spindle was measured under varying conditions, including spindle speed, bearing temperature, spindle orientation (vertical or horizontal), and lubrication supply parameters. The impact of spindle setting and operating conditions on dynamic performance was analyzed with reference to eigen frequencies and damping ratios. The analysis revealed two significant spindle bending modes that exhibit distinct changes in response to spindle speed and temperature. Additional experiments demonstrated slight shifts in eigen frequency and variations in damping ratio concerning the oil supply.