Non-contact Measurement of Dynamic Stiffness of Rotating Spindle

To investigate the dynamic stiffness of the rotating spindle, a non-contact loading method is applied. A magnetic loading device is used to provide swept-sine-wave load, while the spindle displacement is measured with eddy-current-type sensors. Frequency responses of the compliance are then measured, while spindle speeds and warm-up conditions are designed to regulate the temperature status in the spindle. The spindle temperature effects on the natural frequency and peak value are discussed based on the measurement results.