A thermal model to investigate the wire rupture phenomenon for improving performance in EDM wire cutting

A continuous trend towards automation can be noticed in wire cutting electro discharge machining due to the relatively low machining speed and large investments required. In this respect, the wire rupture phenomenon may be considered a major problem, limiting the overall efficiency of the operation. The thermal load on the wire seems to be a governing factor determining wire rupture. This has been proven by a number of tests using an EDM pulse analyzing system. In order to examine the relative influence of various process parameters on the thermal load of the wire, a mathematical thermal model was developed. The model enables the calculation of the temperature rise in the wire due to heat input by electrical discharges and from Joule's heat. The result of this analysis can be used in an adaptive control optimization system in order to maximize the cutting speed, without enhancing the risk of wire rupture.