Effect of Tool Material Properties and Cutting Conditions on Machinability of AISI D6 Steel During Hard Turning

Abstract

Hard turning offers numerous advantages to grinding operation; however, there is a critical need for research to clarify issues related to high cutting forces, high temperatures, and surface roughness to meet the challenges it can offer as an alternate to grinding process. Mathematical models are generated for each response variable (main cutting force, thrust force, cutting temperature, and surface roughness) in terms of actual values of the factors (cutting speed, feed, and tool material) to establish relationships using design expert software for statistical investigation. A 33 full-factorial design with a total of 27 experiments was obtained for parametric analysis and investigation of machinability of AISI D6 tool steel using three different grades of low-content cubic boron nitride (CBN-L) inserts. The parametric analysis study shows that the main cutting force, thrust force, and surface roughness increase with feed. The thrust force and cutting temperature get influenced by tool material properties. It was established that grain size, CBN content, edge geometry, and hardness of the tools affected all the output characteristics. Scanned electron microscopy and energy-dispersive X-ray of the worn tools showed crater wear, chipping, and fracture of cutting edges, while abrasion and diffusion/dissolutions in CBN tools were the wear mechanisms affirmed in this study.