A novel gap flushing insert for sink electrical discharge machining

Gap flushing in sink electrical discharge machining (EDM) is generally accomplished by forcing the dielectric fluid through a hole in the tool (through-tool flushing) or by periodically retracting the tool from the machining gap (jump EDM). Through-tool flushing is limited by the stump left on the workpiece from the flushing hole, and jump EDM by the reduced productivity from when the tool is not engaged in machining. In this context, this paper presents an innovation that involves a rotating flushing hole assembly incorporated within a prismatic tool, which can be self-propelled by the dielectric flow. The novel design is shown to essentially eliminate the formation of the said stump, and to correspond to removal rates surpassing jump EDM.