Parametric modeling and optimization for wire electrical discharge machining of Inconel 718 using response surface methodology

Inconel 718 is a high-nickel-content superalloy which possesses excellent strength at elevated temperatures and resistance to oxidation and corrosion. This alloy has wide applications in the manufacturing of aircraft engine parts such as turbine disks, blades, combustors and casings, extrusion dies and containers, and hot work tools and dies, but the inherent problems in machining of superalloys with conventional techniques necessitate the use of alternative machining processes. The wire electrical discharge machining (WEDM) process has been recently explored as a good alternative of conventional machining methods, but there is lack of data and suitable models for predicting the performance of WEDM process particularly for Inconel 718. In the present work, empirical modeling of process parameters of the WEDM has been carried out for Inconel 718 using a well-known experimental design approach called response surface methodology. The parameters such as pulse-on time, pulse-off time, peak current, spark gap voltage, wire feed rate, and wire tension have been selected as input variables keeping others constant. The performance has been measured in terms of cutting rate and surface roughness. The models developed are found to be reliable representatives of the experimental results with prediction errors less than +/- 5 %. The optimized values of cutting rate and surface roughness achieved through multi-response optimization are 2.55 mm/min and 2.54 mu m, respectively.