Deformation mechanism in wax supported milling of thin-walled structures based on milling forces stability

At mesoscale, dynamic alternating milling forces and relative stiffness of thin wall are the main factors affecting the deformation of thin-walled structures. To improve the machining accuracy and effectively control the thin wall deformation, this paper investigates the control strategies of dynamic milling forces and deformation mechanism in milling of different thin-walled structures. The instantaneous deformation of thin wall in high temperature casting wax supported milling is analyzed. A deformation control method of thin wall based on the dynamic stability of micro milling forces is proposed in highspeed milling process. Three representative milling experiments on microchannel cold plate with cantilevered boundary, single impeller blade with mixed boundaries, and cantilevered structure shaped like variable curvature wavy line are presented. The milling deformation mechanisms of these three thin-walled structures with different target thickness are further investigated in free milling and casting wax supported milling. Compared with free milling, the milling forces and thickness dimension of thin wall machined under different control strategies are analyzed. By monitoring the milling forces in milling of different micro-walled structures, the small difference and fluctuation of milling forces at different positions, together with the reduced thickness errors verify the effectiveness of the control strategies, using high temperature precision casting wax as auxiliary support in reducing the thin wall deflection. Additionally, the optimal milling control strategy of thin wall is determined. (C) 2021 CIRP.