Design and validation of a headstock prototype for dry EDM drilling

Abstract

Electrical discharge machining (EDM) process is very appreciated in the manufacturing of conductive parts with complex geometry. Nonetheless, the use of liquids as a dielectric medium between electrode and workpiece involves important constraints to the EDM machine design concept. Many research works have been carried out using different gases as dielectric medium, the so-called dry EDM. However, further technical developments are required for industrial applicability. The present work proposes an exchangeable headstock prototype for dry EDM machining designed with the intention of evaluating the process potential in industrial applications. Considering the process parameters of spindle speed, gas dielectric flow rate, and electrode diameter, the new exchangeable headstock is capable to cover the most state-of-the-art research works. Moreover, with the designed prototype, dry EDM drilling tests were carried out for its validation, and the effect of spindle speed (500–5000 rpm), gas dielectric flow rate (240–440 l/min), and electrode cross section and material were evaluated in terms of machining speed (MS), tool wear rate (TWR), geometric accuracy, and surface integrity. These validation tests were realized using compressed air as dielectric medium and AISI 1045 steel workpiece. The results demonstrated the proper functioning of the new headstock. Besides, the validation tests showed the MS was increased with the increment of the air flow rate, the TWR mostly depends on the electrode material and no relationship between the process parameters and geometric accuracy and surface integrity.