Specifics of Flushing in Electrical Discharge Drilling

Flushing in electrical discharge machining is essential to obtain high quality results and a good productivity. The flushing conditions in electrical discharge drilling are unique compared to sinking and cutting operations due to high flushing pressures. High flushing pressures lead to high dielectric flow rates in the narrow gap between the tool electrode and the work piece. It was found out, that to much flushing results in negative process behaviour and reduces the drilling speed. However, based on the electrical energy supplied to the gap there is an optimal dielectric flow rate to achieve a high drilling speed. Furthermore it was found out that there is a direct link between removal mechanism and the dielectric flow rate. Multi pulse experiments were carried out to investigate the influence of flushing on drilling speed, removal mechanism and process behaviour.