Milling parameters of Al-Cu and Al-Si cast alloys

The work presented here was carried out on an Al-6%Cu-0.7%Si alloy (used in as cast, T5 and T7 aged conditions), in comparison with B319.0 (T7 by treated at the two places where treatment appears) and A356.0 (T6 treatment) alloys. Wet milling was carried out on 15 blocks of each alloy using new inserts for 120-m machining distance. A total of 75 blocks were employed. The results show that the cutting forces for the Al-Cu based alloys are not affected by the applied heat treatment. The presence of Cu in the B319.0 neutralized, to some extent, the harmful effect of the hard Si particles. Maximum cutting forces were obtained from machining the A356.0 alloy treated in the T6 condition, due to the presence of a high density of hard eutectic Si particles (~ 41500 particles/mm²), in addition to the dense precipitation of ultra-fine Mg₂Si particles. Thus, the presence of 6%Cu in the Al-Cu-based alloy may act as a self-lubricant leading to much smoother finishing surfaces compared with those exhibited by B319.0 and A356.0 alloys. Similar observations were reported on the wearing of the drilling tools. Moreover, after 120-m machining distance, tiny burrs were found adhered to the outer edges of the workpiece, whereas burrs in the case of the A356.0 alloy were separated from the block.