Experimentally Based Prediction of Machining Chatter Characteristics for AMB Spindle

In a previous work, a high-speed spindle was made to attenuate machining chatter through application of robust control to AMB supports. In the present work, tooltip compliance of the levitated system is experimentally measured by impulse testing. Using the compliance measurement, the stability lobe diagram and critical chatter frequency diagram are calculated by means of Nyquist stability theory applied to the cutting force feedback loop. This experimentally based stability lobe diagram quantifies the improvement of machining stability when using the chatter avoiding AMB controller. The chatter frequency diagram is helpful in identifying the onset of chatter and posteriori AMB controller tuning. Also from the compliance data, critical phase shift between the inner and outer cut modulus is calculated for a range of machining speeds. The critical phase shift shows the amount of regenerative effect needed to cause machining chatter at each speed and confirms the advantageous machining speeds found in the stability lobe diagram.