Experimental Study on EDM ECM Hybrid Processes of High-quality Small Hole with Super Depth-diameter Ratio

Traditional machining methods face great challenges when machining small holes with super depth-diameter ratio on difficult to machine materials. At present, electrical discharge machining (EDM) is still one of the most effective methods for machining deep holes on difficult to machine materials, but there are some problems such as poor surface quality. Electrochemical machining (ECM) has the advantage of high surface quality, but it is not as efficient and accurate as EDM in deep hole machining. Therefore, combining EDM and ECM is the most effective way to achieve high efficiency, high quality and high precision machining of deep holes. This study applies low concentration hydrochloric acid electrolytic-dielectrics to EDM ECM hybrid processes. The experimental results confirmed that this electrolytic-dielectrics was superior to traditional neutral electrolytic-dielectrics in terms of machining efficiency and accuracy. To improve the machining accuracy and surface quality of small holes with super depth-diameter ratio simultaneously, this study proposes a method of partial insulation tool electrode. A high-quality and high-precision machining of small holes with super depth-diameter ratio (> 50:1) through process parameter optimization is obtained. This method has broad application prospects in the processing of small holes with super depth-diameter ratio in difficult to machine materials.