Experimental investigations on cutting force and temperature in milling process of copper foam with high porosity

To protect pore structures of metal foam in the machining process, a new milling method was proposed that different filling materials were used for solidification of pore structure. In this way, the milling process was performed using the copper foams with three different types of filling materials (paraffin, rosin, and mixture of hydrogenated rosin and sodium stearate with a mass ratio of 4:1). During milling process of copper foam, the cutting forces and cutting temperatures were measured and analyzed. The surface morphology of copper foam was observed according to the SEM results. Moreover, the conformal rate, which was considered an index to estimate the quality of milling process, was calculated using pore size statistics. Our results show that with the increased spindle speed and feed rate, the conformal rate of pore structure was firstly increased and then decreased. With the increase of feed rate, the cutting temperature was slightly decreased. When the spindle speed was increased, the cutting temperature was increased, while the highest cutting temperature was much lower than the melting temperature of the filling materials. Better conformal performance and high conformal rate were obtained with the hydrogenated rosin and sodium stearate at a ratio of 4:1, at a spindle speed of 300 r/min and a feed rate of 160 mm/min. When the optimized processing parameters were adapted to milling the copper foam with filling material, the conformal rate can reach 96.4%. Correspondingly, the highest cutting temperature and the maximum cutting force perpendicular to the feeding direction and along the feeding direction were 37.4 °C, 44.91 N, and 24.60 N, respectively.