Mechanism study of the electrical discharge ablation milling with a microcutting depth

Abstract

Tool wear inevitably occurs during electrical discharge milling (ED milling), adversely affecting the form precision of machined features. Specifically, radial tool wear negatively influences copying precision. In this study, electrical discharge ablation milling (EDA milling) with a microcutting depth was investigated to improve the machining precision of discharge milling. In the proposed method, the cutting depth of a single layer was kept at the micron level, which is smaller than the discharge gap, and the electrode was set to a fast feeding rate at a constant speed. The microcutting depth of a single layer made the discharge concentrate at the end of the electrode while avoiding the side. Under this method, radial tool wear is prevented to realize high-precision discharge milling. The discharge state and high-precision mechanism of the proposed method were analyzed. Contrast experiments were conducted to compare conventional electrical discharge milling (ED milling), conventional electrical discharge ablation milling with a large cutting depth (EDA milling with a large cutting depth), and EDA milling with a microcutting depth. Results indicated that when peak current was 30A (pulse duration was 150 μs and pulse interval was 120 μs), the machining efficiency of the proposed method (18.8 mm3/min) was 9.5 times that of ED milling (1.97 mm3/min) and was 62% higher than that of EDA milling with a large cutting depth (11.6 mm3/min). Besides, the surface quality and cross-sectional shape precision of the straight groove were significantly improved compared with EDA milling with a large cutting depth.