Abstract: In view of the thin-walled part with low stiffness， the 3D dynamics model in milling process was built on the machining principle. The chatter stability lobes were predicted using the full-discretization method and validated by the experiments. The results showed that dynamic characteristics of the thin-walled part in milling process determine the dynamics model. There is the nonlinear relation between the limited cutting depth and the spindle speed， and the spindle speed has more effect on the chatter stability than other factors. When the modal mass， relative damping and natural frequency increased， the stability intensifies and the shape of lobes is changed simultaneously. The theoretical model provides the guidance for reasonable selection of cutting parameters and improvement of machined surface quality and machining efficiency.

Key words: thin-walled part, milling process, dynamics model, regenerative chatter, stability analysis