Milling stability analysis with considering process damping and mode shapes of in-process thin-walled workpiece.

• The process damping and multiple mode shapes at tool-workpiece contact zone were considered simultaneously with a multi-mode model in four spatial dimensions. • The proposed model considering material removal could assemble the change in mass and stiffness quickly by using geometric judgment conditions, and then the IPW dynamics would be extracted. • Different kinds of frequencies under different dominant modes of milling tool or workpiece were identified and expounded. • The three-dimensional stability lobe diagram (SLD) with the proposed model could predict the stability accurately. Especially when the workpiece dominated the machining process, the comprehensive SLD considering material removal was closer to the experimental results. Reasonable machining parameters would be selected to avoid chatter vibration in the practical processing. As an unfavorable factor of machining process, chatter threatens the machined quality of workpiece, which determines the assembly and fatigue performance of the workpiece. During the interaction between machine tool and thin-walled workpiece, the process damping effect, multiple modes response and dynamic changes caused by the material removal of the in-process workpiece (IPW) will make the machining process more complicated and introduce great difficulties to dynamic modeling and performance prediction. In this paper, we considered the process damping determined by the indentation volume between flank face of milling tool and machined surface, and used multi-mode model to describe this behavior. In order to establish the assembled material removal model of the IPW dynamics with multiple modes, the structure dynamic modification (SDM) and finite element method (FEM) were combined together. The updated third-order full discretization method was applied to solve the dynamic equation in modal space. Then, the three-dimensional stability lobe diagrams (SLDs) with and without material removal along the tool path were obtained respectively by enveloping multiple modes of the IPW and milling tool together. Finally, the cutting tests were carried out. The experiments showed that the assembled model could predict the dynamics of IPW accurately, and the proposed stability analysis model was relatively close to experimental results. Besides, the modes of thin-walled workpiece with weak rigidity do not always play a dominant role in the process of machining. Although the material removal rate is limited by considering the multiple modes of the system, the processing quality can be ensured. [ABSTRACT FROM AUTHOR]