Optimization of process parameters for precise corner accuracy in wire electric discharge machining of AISI D2 tool steel

This work investigates the influence of wire electric discharge machining process parameters on machined corner accuracy and surface integrity in the machining of AISI D2 tool steel. Despite numerous studies on WEDM (wire electric discharge machining) optimization, limited research has addressed corner inaccuracies caused by different machine input conditions, especially hard tool steel like AISI D2. The present study uses the Taguchi L16 orthogonal array to analyze the effect of different process parameters such as pulse-on and pulse-off time, discharge gap, wire speed, and wire tension on kerf width, surface roughness, and corner errors. To rank the influence of process parameters, regression modeling, ANOVA, and standardized coefficient analysis were conducted. Further model validation was done using R2, adjusted R2, RMSE, and residual diagnostics. The findings indicate that pulse-on and pulse-off time significantly affect all the process responses, particularly corner accuracy adversely affected by higher pulse on time; on the other hand, discharge gap, wire speed, and wire tension have minimal effects on process responses. The proposed mathematical model attained high accuracy with an R2 value over 0.90 for every response. The percentage prediction errors during model validation were found to be 3.66%, 13.06%, 8.39%, and 13.69% for kerf width, surface roughness, corner error of the top side, and corner error of the bottom side, respectively. Experimental observation of the heat-affected zone of the selected sample shows variable dimensions with a maximum value reaching up to 78.61 µm caused by critical discharge conditions, along with craters and carbon enrichment on the machined surface. These results provide a predictive framework for improving dimensional precision in WEDM of hard-to-machine alloys.