An Improvement in the Quality of Holes Drilled in Quartz Glassby Electrochemical Discharge Machining

Abstract

ABSTRACTElectrochemical discharge machining (ECDM) is an efficient method for the machining of nonconductive hard and brittle materials. The process is normally quite slow and to increase the speed of ECDM hole drilling the voltage and the electrolyte concentration are usually increased. However, this can result in overcutting and the heat-affected areas can be rather rough. In this study, an innovative composite machining aid that uses a self-developed auxiliary nozzle that produces a coaxial jet was developed. This keeps the rotating tool electrode submerged in electrolyte in the ECDM area at a low level. The electrolyte is constantly renewed and the spark discharge is concentrated on the contact surface of the tool electrode tip and the workpiece material to be processed. The surface quality of the entrance and exit and the roundness of the hole are investigated. An energy monitoring mechanism reduces the output prior to perforation. In this study, 0.1 mm thick quartz glass was drilled in a 5 M KOH electrolyte at 50 V. The results confirmed that the area of the heat affected zone of the electrochemical discharge composite assisted by the method proposed is less extensive than that in an unassisted process. The reduction was 48.23%, the HAZ area at the exit was reduced by 53.21%, and the surface quality at the start and the end of the hole, as well as the roundness, were improved.