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In high-speed milling, the machining system is affected by chatter resulting from the dynamic interaction between the tool and the part. Which can cause a harmful effect on the tool and the machined surface of the part. Chatter occurs more frequently for the milling of thin-walled parts due to their low stiffness. In addition, the dynamic characteristics of thin-walled parts vary along the tool path. The dynamics of the part is therefore the dominant factor that should be considered in the modeling and the study of milling process must be performed in 3D where the third dimension is the tool position. This paper studies the milling stability of Al 7075-T6 thin-walled parts during high-speed milling considering the variation of dynamic characteristics and develops three-dimensional stability lobe diagrams of the spindle speed, axial depth of cut and tool position. The dynamic equations of motion are solved numerically using semi-discretization method. Modal parameters of the tool and the part were extracted experimentally by model tests. Then, cutting tests were conducted to validate the established model by measuring the machined surface roughness which is used as criterion for detecting instability. The experimentally obtained results correspond well with the predicted stability limits. Moreover, influence of different cutting parameters on the machining stability along the tool path was investigated. It is found that the variable speed improves significantly the cutting process, and the best selection of feed per tooth impacts positively on the machined surface quality. |
