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In order to improve the machining efficiency and the surface quality of EDM/ECM, adding a small amount of sodium nitrate into deionized water as the working medium, a novel simultaneous machining approach of EDM and ECM (SEDCM) was developed. In this work, a comparative study was conducted on the SEDCM performance of TC4 alloy using different electrode materials viz. brass, copper and copper-tungsten alloy. In addition, the effects of process parameters, such as peak current, pulse on time and gap voltage on material removal rate (MRR), tool wear rate (TWR), surface roughness (Ra), and surface micromorphology were investigated. The results show that brass electrode provides the smallest MRR, the highest TWR and the worst surface quality. The copper electrode has the smallest average diameter of a single discharge craters and the best surface finish. The MRR and TWR of copper-tungsten electrode are similar to those of copper electrode. As peak current increases, TWR increases and Ra deteriorates for all the electrodes, as well MRR increases and then decreases for copper and copper-tungsten electrodes. Increase in pulse on time and gap voltage, MRR and TWR increases and then decreases gradually. At higher pulse on time and gap voltage, Ra becomes greater for three type electrodes.

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In this paper, the problems of decreasing coupling efficiency and energy distribution divergence of water beam fiber caused by static alignment deviation are studied. Based on the basic conditions of coupling between laser and water beam fiber, the mathematical model of coupling efficiency of water beam fiber is established, and the calculation equation of coupling efficiency is modified. The variation of coupling efficiency and energy distribution of water beam fiber under the influence of static alignment deviation is analyzed by numerical simulation, and the correctness of theoretical derivation and simulation model is verified by experiments. The results show that the lateral deviation changes the transmission path of laser in the water beam fiber to a large extent, and its influence on the energy distribution in the water beam fiber is greater than that of longitudinal deviation and angular deviation.