The Effect of Electrode Material on High Speed EDM Process on Product Quality

Electric Discharge Machining (EDM) is a non-traditional machining process that involved a transient spark discharges through the fluid due to the potential difference between the electrode and the work piece. In this experiment, EDM process on mild steel work piece was conducted using EDM Die Sinking Neu-ar. The electrodes used were copper, brass and graphite. This project is to be conducted using Taguchi method L4 orthogonal array. The parameters to be studied are peak current (12A and 21A), discharge ON time (10μs and 45 μs) and pumping direction (B0 and B1). This research aims to study the factors that influence the machining of different electrodes in electrical discharge machining (EDM) process. Surface roughness was measured using surface roughness tester (SJ-301). Material removal rate (MRR) and electrode wear ratio were determined based on weighting the work piece and electrode using digital weight scale. Then, the result of the experiment was analysed using EXCEL. The higher material removal rate in the EDM machine, the better the machining performance is, while the lower electrodes wear ratio in the EDM machine, the better and accurate performance characteristic is. The results show that copper electrode gives higher material removal rate which is 0.411 g/min than brass and graphite. Brass electrode gives better surface finishing which is 15 μm and graphite electrodes give the better electrode wear rate which is 0.53 among two electrodes. © 2017 Elixir All rights reserved. Elixir Mech. Engg. 103 (2017) 45752-45757 Mechanical Engineering Available online at www.elixirpublishers. com (Elixir International Journal) N.H. Abdullah and Z.A. Ab.Kasim / Elixir Mech. Engg. 103 (2017) 45752-45757 45753 They found that during the experiment, MRR and surface roughness increased with peak current and pulse duration. The effects of EDM current, pulse ON-time and flushing pressure on MRR, TWR, taper and surface roughness when machining cast Al-MMC with 10% SiCp were investigated by Narender Singh et al. (2004). They show the correlations between the MRR, EWR, taper and surface roughness with the parameters of the EDM process. The results showed that with the combination of these parameters, the MRR increased with an increase in peak current and pulse ON-time. Prajapati et al. (2012) found that, the surface roughness is the general quality of a product surface, measured using surface roughness tester, and measured as the arithmetic average Ra (μm). He investigated the performance of different electrode which was brass, copper and graphite materials in EDM in MRR and surface roughness. He found that a brass electrode gives better surface roughness when peak current increased. According to the experiments done by Prajapati et al. (2013), it showed that the surface roughness was mainly affected by the peak current and pulse on time. The higher value of the current causes the more surface roughness and will affect the finishing of surface quality on the machining performances. The research from Khan et al. (2009) found that the increase of current will increase the surface roughness due to stronger spark that makes a crater of higher depth. He studied of electrode shape configuration on the performance of die sinking EDM. The experiment was carried out by using mild steel as a work piece and different shape of copper electrode such as round, square, triangular and diamond. Three current values of 2.5, 3.5 and 6.5 A are used to investigate the surface roughness and MRR and he reported that not give any influence to the surface roughness of the shape of the electrodes. 2. Experimental Setup The procedure begins with the design of experiments bases on Taguchi methods and data analysis using EXCEL. There are divided into three main parts: i. Work piece and electrode materials ii. Equipment iii. Data sources and data analysis. 2.1 Selection of work piece and electrode material 2.1. 1 Selection of work piece The mild steel bar of dimension of 80mm x 50 mm x 30 mm is used as a work piece material, having the typical composition shown in Table 2.1. It is softer and more easily shaped and also bends instead of breaking. Mild steel can be machined, and can be hardened with carburizing. It is the cheapest type of steels and most versatile widely used in industry. Table 2.1. Specification Properties of Mild Steel