Effect of Current and Duty Factor for Different Electrode Shapes on Material Removal Rate in EDM


This paper discusses the performance of Electrical Discharge Machining (EDM) process by changing the bottom shape of the electrode, including two stages: designing the electrodes by turning process then the resulted electrodes were used to machine the workpiece by EDM. The effect of electrode shape on material removal rate (MRR) has been investigated for material of CK 60 carbon steel for workpiece and material of brass for electrode. The shapes of the electrode bottom were flat, conical (with 90º apex angle) and round (with 8 mm radius) of constant diameter electrode of 16 mm. Experiments were repeated for three current values of (10, 20 and 42 A) and three duty factor values of (0.4, 0.8, and 1). The results of experiments showed the main effect of current and duty factor on MRR. From experimental work, it is found that for most of experiments flat electrode gives highest MRR as compared to the two other shapes. A mathematical model was developed by factorial design to predict the values of MRR for different electrode shapes, currents, and duty factors by the Minitab Statistical Software (MSS).