Multi Response Optimization of WEDM Process on OHNS Die Steel Using ANN, SA and GA

1. Introduction

Wire Electrical Discharge Machining (WEDM) is a non-conventional, thermo-electric machining process which has an important role in high-precision and high-performance manufacturing industries due to it is capability of accurate and efficient machining of parts with varying hardness or complex shapes and sharp edges of the work piece (El-Hofy, 2005). In WEMD material removal take place by controlled erosion of the electrically conducting material (Mishra, 1997). The process is based on removing the material from the work piece by a series of discrete sparks between an anode work piece which is immersed in a dielectric liquid medium and continuously feeding cathode wire through the work piece control by a microprocessor (Ghosh and Mallik, 1991). This electric discharge melts and vaporizes small amounts of the work material, and the removed material is flushed away by the flowing dielectric liquid. As the tool wire and the work piece does not make direct contact during machining, so there is no machining stress, chatter and vibration. Therefore, this process can be used in machining of alloys having low machinability and high temperature strength resistance.

In order to achieve high quality, high process safety, minimal manufacturing cost and lowest possible machining time the manufacturing process parameters have to choose in the optimized way. The major factors influencing WEDM process are Pulse On Time (T_on), Pulse Off Time (T_off), Wire Feed, Wire Tension, Servo Voltage, Open Voltage, Peak Current and Dielectric Pressure (Ikram, et al. 2013). The photograph of WEDM setup is illustrated in Figure 1 below.

Figure 1.

Machining setup of WEDM