Hard Turning Operation of Alloy Tool Steel (AISI D3) Using Cubic Boron Cutting Tool

AISI D3 is a high carbon-high chromium tool steel with vast industrial applications. However, its hardenability makes it difficult to machine. This study considers the turning operation of AISI D3 under the soluble oil cooling condition. Three process parameters were considered in the following range: depth of cut (0.2-0.6 mm), feed rate (0.1-0.2 mm/rev) and cutting speed (200-300 m/min). The response surface methodology (RSM) was employed to obtain the feasible combination of the process parameters while the surface roughness was taken as the response of the designed experiment. A centre lathe (CTX 310 eco DMG) was employed for the turning operation while a PVD cubic boron nitride (CBN)-titanium nitride (TiN) coated insert manufactured by the SANDVIK Coromant was employed as the cutting tool. The heat-treated tool steel has a specification of $(\phi 75 \times 250 {\mathrm {mm}}$ with hardness 58 ± 1HRC). The results obtained indicated that the combination of the process parameters that produced the least surface roughness $(0.235 \mu {\mathrm {m}})$ are feed rate (0.15 m /rev), cutting speed (165 m/min) and depth of cut (0.40 mm). There was also a significant agreement between the surface roughness values obtained via physical experimentations and the ones obtained from the predictive model equation generated by the RSM. This study presents empirical results that could assist machinist determine the feasible range of process parameters for the turning operation of AISI D3. The findings could also assists in machining AISI D3 to the desired degree of surface finish.