Stability predictions of milling with variable spindle speed using an improved semi-discretization method

During milling, mechanical vibrations known as “chatter” result in lessened productivity, poorer product surface finish, and decreased cutting life of the tool. Thus, it is desirable to predict and avoid the onset of this instability. In this paper, we propose an improved semi-discretization method, based on the Floquet theory, to predict the sinusoidal spindle speed modulation of milling processes. Compared with the non-improved semi-discretization method, the accuracy and efficiency of the proposed algorithm are verified. In addition, stability is predicted using benchmark examples. The stability charts for variable spindle speed milling are compared with those for constant spindle speed milling. The results show that chatter can be effectively suppressed by varying the spindle speed.