Investigation of EN8 & EN31 steels in vertical milling machine for SR and MRR by adopting optimization approach

The optimum machining parameters of milling operations are of great concern with manufacturing environment. The aim of the work is to observe the impact of variables on outcomes like surface roughness and material removal rate for EN8 and EN31steels. In these, EN8 are used for moderately stressed parts of motor vehicles while EN31 are used for components that are subjected to severe abrasion, wear or high surface loading due to its high resisting nature against wear. The experiments have conducted on a vertical milling machine using a carbide tool. This investigation deals with the optimization of the milling parameters, as spindle speed, feed rate and depth of cut by using Taguchi's optimization and GRA techniques to select the best combination of input parameters towards maximum material removal rate and minimum surface roughness for these materials. These milling parameters were optimized by utilizing Taguchi's L9 orthogonal array, signal-to-noise ratios and analysis of variance. The analysis reveals that the spindle speed is the dominant factor affecting surface roughness and MRR. Spindle speed contributes 97.38% and 72.39% for SR and 51.37% and 14.45% for MRR towards EN8 and EN31 respectively. The response table of S/N ratios for GRG ranked spindle speed at1 for EN8 and EN31 individually. Further, the optimum level of process parameters for attaining optimal values of outcomes by employing GRA. The gray relational analysis reveals that the spindle speed at 228 rpm is the dominant factor affecting the consequences.