Effect of cutting speed on the performance of coated and uncoated cutting tools in turning nodular cast iron

This paper presents the results of an experimental investigation on the effect of cutting speed in turning nodular cast iron with coated and uncoated cutting tools. Three different carbide cutting tools were used, namely TiCN + TiC + TiCN + Al₂O₃ + TiN-coated carbide tools with multilayer coating of 7.5 and 10.5 μm thickness and uncoated WC/Co tool. Turning experiments were carried out at four different cutting speeds, which were 125, 150, 175 and 200 m/min. Feed rate (f) and depth of cut (a_p) were kept fixed at 0.25 mm/rev and 1.5, respectively, throughout the experiments. Tool performance was evaluated with respect to tool wear, surface finish produced and cutting forces generated during turning. Uncoated WC/Co tool was the worst performing tool with respect to tool wear and was the worst with respect to surface finish. If tool wear, surface finish and cutting force results are considered together, among the three tools studied, 10.5 μm thick multilayer TiCN + TiC + TiCN + Al₂O₃ + TiN-coated carbide tool with external TiN layer is the most suitable one for turning nodular cast iron, especially at high cutting speeds.