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Problem statement: Electrical Discharge Machining (EDM) is now a well-established machining option in many industries. Tungsten carbide (WC-Co) is an important tool and die material mainly because of its high hardness, strength, wear resistance and high melting point. Normally, EDM is capable of machining geometrically complex or hard material component, that are precise and difficult to machine. The objective of this research is to study the performance of different electrode materials on tungsten carbide workpiece with EDM process. Approach: The electrode materials were graphite (Poco EDM-3), copper-graphite (Poco EDM-C3) and copper-tungsten (solid).The important parameters were discharge current, on time, off time, open-circuit voltage and electrode polarity. A workpiece material was a tungsten carbide (W 90-Co10). Results: The results show that the electrode negative polarity performs very well, Poco EDM-3 gives higher Material Removal Rate (MRR). Both powder electrode (EDM-3 and EDM-C3) give the better MRR and EWR more than solid electrode. Conclusion: The suitable duty factor is 11%. The Surface Roughness (SR) of copper-tungsten give the best when current peak intensity not over 20 amperes.

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The performance of electrical discharge machining for drilling holes decreases with machining depth because the conventional flushing and electrode cannot completely eliminate debris particles from the machining area. In this study, a modified electrode for self-flushing in the electrical discharge machining process with a step cylindrical shape was designed to improve machining performance for deep hole drilling. The experimental results of the step cylindrical electrode showed that the material removal rate increased by approximately 215.7%, 203.8%, and 130.4%, and the electrode wear ratio decreased by approximately 47.2%, 63.1%, and 37.3%, when compared with a conventional electrode for the diameters of 6, 9, and 12 mm, respectively. In addition, the gap clearance and concavity of the side wall of the drilled hole was reduced with the step cylindrical electrode. The limited high flank of the electrode led to an increase in the escape area of the debris that was partially removed from the machining area, and the limited secondary spark on the side wall of the electrode resulted in a reduction in machining time.

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