Electrode wear investigation on sinking-electrical discharge machining of Cu-electroplated Al: Discharge current and pulse-on time effect

Abstract

Sinking-EDM is a non-conventional machine that utilizes electrical energy that is converted to thermal energy which can produce spark on gap between electrode and workpiece with flowed by dielectric fluid. The spark will produce an erosion and then transform to a crater that is effecting electrode and workpiece melt. It will decrease the mass of electrode during EDM machining until cause it worn down. The materials processed on EDM machine are Al and Cu-electroplated Al using CuCr electrodes. Cu-electroplated Al is a materials obtained from aluminium coated by Cu using electroplating in order to increase its electrical conductivity. Experimental method are used to pull up data, the parameter set are discharge current of 4, 7, 10 A and pulse-on time of 50, 75, 100 µs, while the result to be analyzed were electrode wear rate (EWR) and then did a comparison EWR by workpice material Al and Cu-electroplated Al in accordance set parameter are discharge current with value 7 A and pulse-on time with values 50 µs, 75 µs, 100 µs. An EWR value can be calculated by measuring the electrode weight loss during the EDM process with a digital scale. SEM test is carried out on the electrode that produces the lowest and highest EWR to clarify the phenomenom that occurs, and SEM test equipment are used to access electrode morphology of EWR results.The result showed that the higher the value of the discharge current used EWR would also be increase, while the higher pulse-on time value used EWR were decrease. The highest EWR occurs at parameter discharge current 10 A and pulse-on time 50 µs with a value of 0.478 mm3 min−1, while the lowest EWR occurs at parameter discharge current 4 A and pulse-on time 100 µs with a value of 0.008 mm3 min−1. The highest value in Cu-electroplated Al workpiece material with parameter discharge current 7 A and pulse-on time 50 µs is 0.119 mm3 min−1, while the highest EWR value in Al workpiece material with same cutting parameter is 0.068 mm3 min−1.