Experimental investigation of flank wear and surface roughness during hard turning of AISI H11 steel with CBN tools

Abstract

Hard turning of AISI H11 steel using TiN coated cubic boron nitride (CBN) tools is carried out to investigate the effect of cutting conditions on flank wear and surface roughness. The face centered central composite design is used to develop the nonlinear model of flank wear and surface roughness as a function of cutting speed, feed rate and work-piece hardness. The sequential approach is used to conduct the experiments. First, a full factorial (2³) experiments with three centre points are conducted. If factorial design detects the curvature then additional experiments are required in second part. The results show that linear model was best suited for flank wear, whereas for surface roughness model, the six axial points are added to build a non-linear model. A linear model best fits the variation of flank wear with cutting speed as the most affecting parameter contributes 79.52%, plus work-piece hardness and feed rate contribute 14.75% and 2.65% respectively, whereas interaction effect between cutting speed and work-piece hardness provides secondary contribution of 1.53%. A non-linear quadratic model of surface roughness best suited with major contribution of feed rate, second work-piece hardness and interaction effect of cutting speed and feed rate with quadratic effects of all parameters.