Optimization of wire electrical discharge machining (WEDM) process parameters using genetic algorithm

Wire electrical discharge machining (WEDM) is a special form of traditional electrical discharge machining in which the electrode is a continuously moving conducting wire. The mechanism of metal removal in wire electrical discharge machining involves the complex erosion effect from electric sparks generated by a pulsating direct current power supply. The sparks generated between two closely spaced electrodes are immersed in dielectric liquid. However, dimensional accuracy and surface finish largely depend on process parameters such as discharge current, pulse duration, pulse frequency, wire speed, wire tension and dielectric flow rate. An experimental study has been carried out on a Robofil 100 WEDM machine to identify various significant control factors and their interactions that affect the machining performance such as metal removal rate (MRR) and surface finish (SF) based on Taguchi method. The relationship between control factors and responses like MRR and SF are established by means of non-linear regression analysis resulting in a valid mathematical model. Finally, genetic algorithm, a popular evolutionary approach, is used to optimize the wire electrical discharge machining process with multiple objectives. The study demonstrates that the WEDM process parameters can be adjusted to achieve better metal removal rate and surface finish simultaneously. IPC Code: B23H 1/00 Wire electrical discharge machining (WEDM) is a special form of the traditional electrical discharge machining process in which the electrode is a continuously moving electrically conductive wire. Sparks are generated between two closely spaced electrodes immersed in dielectric liquid which is continuously forced fed to the machining zone to flush away the eroded particles. The movement of wire is controlled numerically to achieve the desired three-dimensional shape and accuracy of the workpiece. In most cases, horizontal movement of the work table (controlled by computer numerical controlled on modern machines) determines the path of the cut. However, WEDM allows intricate cutting and shaping of materials to nearly any threedimensional size and shape. Past works indicates that extensive research has been carried out to study the effect of various machining parameters on metal removal rate (MRR), surface roughness, cutting speed, wire rupture and wire craters. Rajurkar and Wang 1 extensively experimentally investigated the effect of machining parameters on machining performance outputs, viz.,