Machinability Assessment through Experimental Investigation during Hard and Soft Turning of Hardened Steel

In this study, experimental investigations were carried out to assess the machinability of hardened AISI 4340 steel during hard (55 HRC) and soft turning (35 and 45 HRC) using TiC mixed alumina ceramic tools. Mathematical models, which can predict the machining performances, namely, chip-tool interface temperature, cutting forces and surface roughness were developed based on experimental observations. Effect of workpiece hardness and cutting parameters, namely, cutting speed, depth of cut and feed on different responses were analyzed by performing ANOVA technique. Experimental observations indicate higher cutting forces, higher chip-tool interface temperature and lower values of surface roughness for harder workpiece. Feed value has been observed to have more prominent effect on surface roughness. However, the average chip-tool interface temperature has been observed to get more influenced with cutting speed and depth of cut. On the other hand, cutting forces, especially radial component of force which was largest in magnitude amongst the tangential and feed cutting forces, has been observed to get more affected with depth of cut followed by feed value.