A Study on Diamond Turning of Al-Mg Alloy (2nd Report): Mechanism of Machined Surface Generation with Worn Tool

It is generally known that machined surface roughness can be improved with the increase of cut distance just after start of cutting on diamond turning of an Al-Mg alloy. Even for the diamond tool, the tool wear increases as cut distance. In this paper, the effect of the tool wear growth on machined surface roughness was examined on the turning experiments of an Al-Mg alloy. The following results were obtained. (1) Tears generated on the side cutting edge of a straight tool deteriorate machined surface roughness at a positive tool setting angle. But tears decrease as tool wear growth. (2) It is clear that the machined surface roughness has a strong correlation with the cutting edge recession of the tool wear. (3) A residual stock removal is generated at a cutting edge recession distance of more than 0.3 μm. Since the residual stock removal distance is cut off by the trailing end cutting edge, the machined surface roughness is improved after some cut distance.