Effect of Intermetallics and Drill Materials on the Machinability of Al-Si Cast Alloys

The present study was conducted on the machinability of 396 alloy (containing approximately 11% Si) and B319.2 alloy mainly to emphasize the effects of Fe-intermetallics, i.e., alpha-Fe, beta-Fe, and sludge. The results demonstrate that the presence of sludge in the form of hard spots has a significant effect on cutting forces and tool life, in that it decreases drill life by 50% compared to the base alloy. The formation of the alpha-Fe phase in the M1 base alloy has a beneficial effect on tool life in that this alloy produces the highest number of holes drilled compared to alloys containing sludge or beta-Fe; this result may be explained by the fact that the formation of the alpha-Fe intermetallic, with its rounded Chinese script morphology and its presence within alpha-Al dendrites, is expected to improve matrix homogeneity via hardening of the soft alpha-Al dendrites. Increasing the Fe-content from 0.5% to 1% in the 396-T6 alloy containing 0.5% Mn produces a distinct improvement in alloy machinability in terms of cutting force and tool life. The addition of Fe and/or Mn appears to have no discernible effect on the build-up edge area (BUE) and chip shape.

Automated summary

This study focuses on the machinability of alloys containing silicon and iron intermetallics. The presence of sludge has a significant effect on cutting forces and tool life, while the formation of alpha-Fe phase improves the tool life. Increasing Fe content can enhance the alloy's machinability.