Cutting performance of coated carbide inserts in hard turning of hardened AISI D2 cold work tool steels

Abstract

Hard turning is a dry machining process that is often preferred over conventional grinding to achieve final dimensions on a workpiece that is already in a hardened state. In this study, hard turning process was preferred due to its numerous advantages such as low machining time, low total production cost, better surface integrity and better environmental effect because of elimination of coolant. The hardness of the material being machined can cause significant wear on the cutting insert. This study investigated the effects of TiCN + Al2O3 + TiN coated carbide inserts on the machining process of hardened AISI D2 cold work tool steel. The temperature of cutting zone, tool wear, flank wear, surface roughness, hardness, chip formation, and microstructure were all measured as a function of cutting speed. A real-time monitoring system was used to measure wear at the tool edge and temperature on the flank face of the cutting insert. The results showed that increasing cutting speed from 100 to 157 m/min led to higher cutting edge temperatures (from 585 to 713°C, respectively) and lower tool flank wear (from 14.6 to 10.8µm, respectively). The multilayer coated carbide inserts produced a ground-quality surface finish with a roughness value of 0.10–0.15 μm. Achieving high cutting edge temperature, low tool flank wear and fine-grinding quality surface finish underscore the effectiveness of using multilayer-coated carbide inserts in the hard turning of hardened steels.