Dynamics and stability of high axial depth milling of thin-walled parts

In finish milling of thin-wall parts, chatter stability is governed by the dynamic response of both the milling tool and workpiece. In the literature, most of the stability models consider single-point contact with shallow axial cutting depths, i.e., point milling, where the mode shape dependent dynamic response is ignorable. On the other hand, as far as high depth milling processes, i.e., flank milling, are concerned there is a line of contact along the axial direction of the milling tool, rather than a single-point of contact. Consequently, mode shape dependent dynamic response turns out to be significant for accurate prediction of stability limits. In this study, the axial variation in the frequency response function (FRF) of the milling system is considered in prediction of stability diagrams. The novel contribution of this study is the experimental verification of the proposed stability model by using a practical workpiece dynamics model. In this respect, the validity of the proposed model was examined under various cases to provide an understanding to develop chatter-free machining strategies, and to demonstrate significant advantage of considering the mode shape dependent FRF variation along the axial direction.