Chatter mitigation for the milling of thin-walled workpiece

Abstract

During the milling process of thin-walled workpiece, chatter is the major obstacle in achieving desired accuracy and productivity of the final part due to its low rigidity. In this paper, a novel method is proposed to mitigate the chatter of the thin-walled workpiece by submerging the milling system in viscous fluid. To evaluate the effectiveness of the presented method, the influence of the viscous fluid on the milling force coefficients is investigated, and the modal parameters of the thin-walled workpiece are identified under dry and viscous conditions respectively. It is found that compared with the dry milling, the milling force coefficients reduce significantly under viscous fluid condition due to the lubrication. Besides, the damping of the milling system increases substantially under viscous fluid condition, and the natural frequencies of the milling system decrease owing to the added mass of the viscous fluid. The milling stability lobe diagrams are predicted based on the numerical integration method by taking multiple modes of the thin-walled workpiece into consideration. A series of milling tests are conducted to verify the stability lobe diagrams and confirm the effectiveness of the proposed approach. The vibration displacement signals are measured and then analyzed in time-frequency domain to demonstrate the state of the milling process. Moreover, the surface finishes of the thin-walled workpieces are compared. The results show that the thin-walled workpiece chatter could be suppressed greatly with the proposed method and higher stability limit can be achieved.