Regenerative chatter vibrations may result in shortened tool life and poor surface finish, and hence should be avoided in practice. Since the Spindle Speed Variation (SSV) method has been certified as a feasible and effective way, the issue of speed variation parameters selection has yet to be solved. Based on the discussions of energy accumulation process in chatter and in vari-speed cutting, an analytical method was proposed to select spindle speed variation parameters. The variation of the phase delay between the inner and the outer modulations was regarded as an important argument that reflects the energy accumulation process. Two phase delay related coefficients were proposed for analyzing the mean energy accumulation process and regional energy accumulation enhancement. The importance of spindle acceleration for chatter suppression was also explained. The phase delay based analytical method was verified by numerical simulation and turning experiments
