Influence of Discharge Current in Drilling Hole of Weld on JIS SKD61 Tool Steel by Using Electrical Discharge Machining Process

Abstract

This research aimed to study the efficiency of drilling hole with the electrical discharge machining process (EDM) of JIS SKD61 tool steel. Which was welded to repair by using the shield metal arc welding (SMAW) and gas metal arc welding (GMAW) processes. The welded specimens were sparked with two different electrodes of tool such as brass, and copper. The main factor of discharge current was set up 3 levels of 2.5, 3 and 3.5 Ampere. Then, the performance efficiency was evaluated by the material removal rate (MRR), and electrode wear ratio (EWR), surface roughness (Ra), and appearance of entrance-exit drilled hole, respectively. The experimental results were found that the drilled hole of the SMAW weld sparked by brass electrode, and discharge current of 3 Ampere had the highest material removal rate of 21.458 mm²/min, and electrode wear ratio 82.1 percentage. The average of lowest surface roughness of the SMAW weld which was conducted with Cu electrode, discharge current of 3 Ampere having of approximately 1.9457 micrometer. The appearance of entrance-exit drilled hole of SMAW as well as GMAW welds had the dimensional analysis of entrance drilled hole larger than 1 millimeter and smaller than 1 millimeter for exit drilled hole from using both electrodes and entire discharge current set up.