Experimental investigation and modelling of WEDM process for machining nano-structured hardfacing material

Abstract

In recent years, nano-structured hardfacing alloy constituting fine carbides, borides and boro-carbides have become pioneered in modern manufacturing industries due to their superior properties (excellent hardness, toughness and wear resistance) even at elevated temperatures. A nano-structured hardfacing alloy component was produced using manual metal arc welding process for making turning tool insert. The present paper investigates the effect of wire electrical discharge machining (WEDM) parameters such as discharge pulse time, discharge stop time, servo voltage, wire tension and wire feed rate on machining performances viz. material removal rate, machining time and surface roughness after proof-machining of welded nano-structured hardfacing material. Taguchi’s (L25) orthogonal array has been used to perform the experimental runs using conventional brass wire and zinc-coated wire electrodes, respectively. A combination of Taguchi’s robust design concept with principal component analysis has been applied to optimize the process parameters. For brass wire, the optimal settings of the input process parameters corresponds to discharge pulse time 0.45 µs, discharge stop time 8 µs, servo voltage 35 V, wire tension 800 g and wire feed rate 7 m/min, respectively. Similarly, for zinc-coated brass wire, the corresponding settings are discharge pulse time 0.5 µs, discharge stop time 11 µs, servo voltage 41 V, wire tension 600 g and wire feed rate 7 m/min. This paper also establishes the inter-relationships of various WEDM machining parameters and performances by employing response surface methodology-based approach. A confirmation test has also been carried out with the optimal process parameters to conform to the experimental result.