Understanding the behaviour of workpieces' bulk temperature during laser-assisted turning of Ti6Al4V alloy and heating of Al-SiC metal-matrix composite rods
Although laser-assisted turning (LAT) has been studied for decades, little is known on the effect of bulk temperature rise and residual temperature in the workpiece. Here we report an investigation on a comparison of bulk temperature characteristics in LAT of Ti6Al4V alloy and laser heating of Al/SiC metal matrix composite (MMC) as the two materials have significant differences in thermal conductivities. The research shows that at a low cutting speed with a low laser power density, and a larger laser beam spot, commonly used in previous LAT processing of Ti6Al4V alloy and Al/SiC MMC processes, it may cause too much heat accumulation inside the bulk material, particularly for the material with higher thermal conductivity. A new processing strategy for LAT is proposed based on this study, which combines high cutting speed, high laser power density, and a smaller laser beam spot size to avoid heat accumulation in the workpiece bulk and energy wastage during LAT of materials with high thermal conductivities. Besides, it is found that the cutting tool temperature at 0.3 mm cutting depth is higher than that at 0.5 mm cutting depth during LAT of Ti6Al4V, which is opposite to that in conventional machining.