High Speed Drilling of Aluminum Alloy

A performance test of drilling in 390 aluminum alloy, of which the drilling machinability is relatively unknown, was conducted using three different drill point geometries-- HSS-twist drill, coolant feeding twist drill, and carbide-tipped twist drill. No problems were encountered in terms of chip and formation and consequently, chip ejection was satisfactory. However, a mushroom-type burr on the entrance side and breakout on the exit side were observed when relatively higher drilling speeds were applied. In conclusion, the carbide-tipped drill confirmed its superiority in terms of drill wear and hole quality. The reason for this fact can be explained only after extensive investigation.