Milling stability prediction for flexible workpiece using dynamics of coupled machining system

An efficient machining is limited by the chatter of machining system including spindle and support, which would cause poor surface quality. This paper proposed an improved stability prediction method based on the dynamics of machine tool. Dynamics of the support are considered into the stability prediction of machining process. The spindle was modeled by the receptance coupling substructure analysis method to predict the dynamics at the tool point. The mathematical model of the closed manufacturing system (machine tool, spindle, holder, and tool) was given, as well as the details of joint contacts. The model was used to obtain the system characteristics, and the FRFs of the tool point were obtained from the model in frequency domain. Moreover, the stability limitation for machining system were developed to create the stability lobe diagram with the FRFs of both the spindle and support. Experimental results showed that the depths of improved stability lobes were smaller than those of the original ones, and the improved lobes were more accurate for the stability predictions. The machined surface quality showed that the stable machining system was beneficial to produce good surface. This improved method is helpful for the stability calculation and machining parameter selection especially when milling a thin-walled workpiece or a weak clamping fixture.