Influence of Dielectric Flushing in Electrical Discharge Machining Process on the Machinability for Small Hole Drilling on AISI P20 Tool Steel

Abstract

Drilling small holes is difficult to produce conventional machining process due to the requirement of high rotational speed of spindle and easily damage of drilled bite cutting tool. Technological developments have led to modern machinery that uses electrical parameter control to induce sparks under cover of dielectric fluid. The machining process uses an electrically conductive tool, called an electrode, to spark with the specimen under the dielectric fluid barrier, so that the mechanical properties of the workpiece do not affect the machinability of the material removed. This research is to study the influence of dielectric fluid discharge flushing pattern on the ability of small-hole drilling in the process of electrical discharge machining. Brass tubes with a diameter of 1 mm (0.40 mm inner diameter) were drilled into AISI P20 tool steel. The work material is a thickness of 25 mm. Controlling of dielectric fluid injection is flowed through the core and combined with side flushing for both with and without covering the workpiece surface with dielectric fluid. The experimental results found that the injection of dielectric fluid through the core combined with side flushing has a higher material removal rate than the conventional electrical discharge machining. However, the covering with dielectric fluid resulted in higher electrode wear ratio but the difference size of inlet and outlet holes was reduced.