Modeling and optimization in dry face milling of X2CrNi18-9 austenitic stainless steel using RMS and desirability approach

Stainless steel is characterized by a poor machinability due to its high ductility, and low thermal conductivity. The objective of this work is to model the output responses namely; surface roughness (Ra), cutting force (Fc), cutting power (Pc), specific cutting force (Ks) and metal removal rate (MRR), during the face milling of the austenitic stainless steel X2CrNi18-9 with coated carbide inserts (GC4040). For so doing, response surface methodology (RMS) is used. A full factorial design (L27) is selected for the experiments and the ANOVA is used in order to evaluate the influence of the cutting parameters namely; cutting speed (Vc), feed per tooth, and depth of cut (ap) on the out-put responses. The optimization is carried out, by using the desirability function (DF), according to three cases; minimizing (Ra), maximizing (MRR), and compromising between (Ra) and (MRR). The results reveal that both of (Ra) and (Ks) are mostly influenced by (fz). Both of (Fc) and (Pc) are found considerably affected by (ap), while (MRR) is influenced by both of (fz) and (ap). The optimum cutting conditions corresponding to the third case are: (Vc = 222 m/min, fz = 0.2 mm/tooth and ap = 0.9 mm). Furthermore, the poor machinability of the austenitic stainless steel is confirmed by the micro-chips welded on the machined surface. Nevertheless, the values of (Ra) did not exceed 2 μm for the admissible tool wear [VB] of 0.3 mm.