Influence of Melt Quality on Machinability of HPDC Al9Si3Cu

In general, many cast parts require a final surface finish which could be sand blasting, grinding, or machining. In such applications, the cutting tool life is a critical parameter where the mass production rate becomes important. Therefore, in this work, the correlation between melt quality and machinability of the high-pressure die-cast Al9Si3Cu alloy was investigated. Prior to casting, reduced pressure test samples were collected to quantify the melt cleanliness by means of bifilm index. The tool life was measured based on the fracture of the PCD (polycrystalline diamond) cutting tools. It was found that, when the bifilm index was high (i.e., bad quality), 16 cutting tools were used for the machining of 10,000 parts. On the other hand, when the bifilm index was low (good quality melt), only 4 tools were used for 12,000 machined parts.