Effect of different dielectrics and work piece vibration on electrical discharge machining (EDM) / Norliana Mohd Abbas

Electrical Discharge Machining (EDM) is one of the non-traditional machining techniques. It has been widely used in Malaysia for machining plastic injection moulds, stamping dies and parts for automotive, defense, electronic and telecommunication industries. The process is based on removing material from a part by a series of repeated electrical discharges between a tool called electrode and the work piece with the presence of dielectric. The dielectric serves as the transportation of removed particles, remains electrically non-conducting until the breakdown voltage is reached, reconditions the dielectric strength, increases the energy density in plasma channel and cools the electrode. A survey was conducted in a few industries in Selangor area and found that Tungsten Carbide, ASSAB 718HH and SKD 61 are the commonly used materials for making moulds. Different industries are using different dielectrics for machining similar materials, which prompted this investigation to find the machining performance of the three materials using different dielectrics. The performances of machining using different dielectrics are measured through material removal rate (MRR), tool wear ratio (TWR) and surface finish (SF). Three different types of dielectrics viz., Kerosene, Novis and Amoil were employed in the experiments using copper electrode. 60 specimens were used for the study.