Nonlinear process damping identification using finite amplitude stability and the influence analysis on five-axis milling stability

Abstract

Complex aerospace parts with difficult-to-cut materials AerMet100 etc. should be processed by five-axis milling at low spindle speed, in which the process damping cannot be ignored in stability analysis. Based on the established nonlinear process damping and relevant equivalent process damping coefficient model, a 3D stability lobe diagram (SLD) considering the finite amplitude stability is proposed. A novel indentation coefficient identification method of the nonlinear process damping is proposed by using the finite amplitude stability region, which avoiding the experiment identification of accurate critical cutting depth in inverse stability solution method, and a turning experiment is designed to identify the indentation coefficient of AerMet100 materials. Due to the distribution of process damping force is varied with the cutter-workpiece engagement (CWE) which can be changed by tool orientation, thus the critical cutting depth with considering or not the process damping under different tool orientation are compared and analyzed. The results indicate that critical cutting depth magnitude distribution can be affected by the process damping, and the percentage increase in cutting depth has significant relationship with tool orientation and the frequency response function (FRF). Finally, the influence rule of tool orientation on stability boundary is concluded and the optimization criteria is given.