Discharge Gap and Relative Discharge Ratio in Dry Electrical Discharge Machining

摘要

Electrical discharge machining in gas (dry EDM) is a promising alternative technology for conventional liquid dielectric EDM because of its environmental friendliness and low tool relative wear. However, the machining performance of the technology needs further improvement. To progress this research line and improve the machining performance of dry EDM (DEDM) from the servo strategy viewpoint, different machining parameters for the inter-electrode gap and the relative discharge ratio characteristics were first studied. The experimental results revealed that variation in the discharge gap was not obviously related to variation in the machining parameters, and the inter-electrode gap varied in the range of 8-20 μm under the conditions of experiments; the normal spark discharge ratio was very low in DEDM, being only ～2%-3%; excessive open circuits and frequent short circuits existed in DEDM, which restricts machining efficiency. Based on the gap experimental results, tentative experiments with different servo strategies were conducted, and the preliminary experimental results showed that the material removal rate could be improved and that abnormal discharge ratios could be deduced with the modified strategy.