Abstract
The paper presents an analytical method to predict critical cutting conditions for regenerative chatter vibration in ball end milling process. The ball end milling is an important precision machining process, which is used in production of impellers, screw propellers and turbine blades with free-form surfaces. As these thin structures are flexible, the regenerative chatter vibration often occurs and causes severe problems such as short tool life and deterioration of surface quality. Therefore, an analytical model is developed with consideration of tool inclination around cutting feed direction, and it is applied to predict the stability limits at varied inclination angle in the present research. The ball end milling experiments are also conducted at various inclination angles to verify the developed analytical model. It is confirmed that the critical depths of cut predicted by the developed model agree qualitatively with experimental results at various tool inclination angles. Both the analytical and experimental results show that the critical depth can be increased considerably by the tool inclination around the cutting feed direction, and thus it is expected that the developed model will be useful to optimize tool path, inclination and other machining conditions for highly-efficient ball end milling of the flexible workpieces.
