Investigation of cutting parameters affecting on tool wear and surface roughness in dry turning of Ti-6Al-4V using CVD and PVD coated tools

There are some problems in the machining of titanium alloys with excellent properties such as high strength, good corrosion resistance, long service life and low weight. The leading problem appears to be the fast tool wear and the bad machining surface. Therefore, in this study, it was investigated whether cutting parameters have effect on tool wear and surface roughness by turning under dry cutting condition of Ti-6Al-4V alloy with excellent properties. CVD (TiCN + Al2O3 + TiN) and PVD (TiAlN) coated WC tools were used in the experiments. Then the Ti-6Al-4V alloy turned with the combinations of the different cutting speed, feed rate, cutting long and depth of cut. We observed that the tools wear in both CVD and PVD coated WC tools increased with increasing the cutting speed, feed rate, depth of cut and cutting length. However, while tools wear increased with increasing cutting speed, the surface roughness reduced to an optimum level. Especially, the surface roughness was worsened above the optimum level changing with increasing the feed rate, cutting length and depth of cut. The tool wear with PVD coated WC tools was observed to be less than the CVD coated WC tools. However, the values of the surface roughness obtained with PVD coated WC tools with increase in depth of cut, feed rate and cutting length has given us higher values when compared to CVD coated WC tools.