Effects of multi-pass cutting during wire electrical discharging

Abstract

Abstract In recent years, the use of wire electrical discharge machining (WEDM) has gained momentum for processing hardened alloys. The machining of a hardened alloy commonly reveals poor surface finish and poor corner accuracy. In order to improve the machining performance, multi-pass cutting was employed during wire EDM of Monel 400 alloy. In this work, multi- pass cutting is achieved by one rough cut followed by two trim cuts. Control factors such as offset distance, pulse-on time (Ton), corner angle, flushing nozzle height, pulse-off time (Toff), open circuit voltage and wire tension are selected as control factors in so far as the process criteria results in reduced speed, corner error and surface roughness. The experiments were carried out using Taguchi design, and the results were analyzed. These showed that surface finish and corner accuracy were improved if the machining had been performed with a single trim cut. The outcome of the results revealed that the use of a trim cut more than once adversely affects the productivity and accuracy of the products in question. Moreover, a comparative study on (i) a single pass cut versus a trim cut (ii) a trim cut versus path modification was carried out.