Influence of Electrical Parameters on the Machining Performance in the Small Hole Drilling by EDM Process

Abstract

This research aims to study the influence of controlled parameters on the machining performance for small hole drilling by an electrical discharge machine. Tubular copper with an outside diameter of 1 mm was used as an electrode. JIS SKD 61 grade steel at a depth of 40 mm for machining was used as a workpiece. The experimental results show that machining speed and electrode wear drastically increased with the discharge current. The high machining performance with varied pulse on-time occurred in the range of 16 to 28 μs. The machining time and electrode wear ratio increased with a decreased pulse off-time. In addition, the lowest difference in the dimension of the entrance and exit of the drilled hole at approximately 0.030 mm appeared at the pulse off-time of 6 μs. However, the high machining speed and electrode wear ratio occurred at the low dielectric pressure of 20 kg/cm2. Furthermore, the machining performance reduced and slightly fluctuated with the varied dielectric pressure in the range of 40 to 80 kg/cm2.