Electrochemical Arc Machining (ECAM) has demonstrated considerable potential for efficient machining of difficult-to-cut materials. However, the relationships between machining signals and material removal characteristics in ECAM are poorly understood. In this study, the impedance characteristics of ECAM machining circuit were investigated. Results show that the equivalent impedance of arc discharge is significantly less than that of Electrochemical Machining (ECM), leading to a higher arc discharge current. As the feed rate increases, the Inter-Electrode Gap (IEG) decreases, resulting in higher arc discharge frequency, longer sustaining time, and increased peak current. Arc discharges in a small IEG exhibit a high electrical equivalent, which is 2.34 times that of ECM. At a feed rate of 200 mm/min, arc discharge contributed to 93.59 % of the total material removal, achieving a Material Removal Rate (MRR) of 751.96 mm³/min. Furthermore, with increasing tool electrode feed rate, more electrical energy was effectively utilized for arc discharge processes. Under these conditions, a larger proportion of the arc discharge energy was allocated to the workpiece, minimizing the relative electrode wear rate to 4.61 %. The enhanced arc discharge effect led to a significantly recast layer, while the electrochemical effect remained relatively stable. Consequently, the groove dimensional characteristics and surface morphology were predominantly influenced by arc discharge behavior. This study elucidates the intrinsic relationship between material removal mechanisms and machining current in ECAM, thereby offering a foundation for machining optimization and industrial application. Finally, the ECAM technique was successfully utilized for the efficient machining of an optical load-bearing structure.

Electrochemical drilling (ECD) provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines. The value and fluctuation of electrolyte flowrate can seriously affect the machining stability and hole quality in ECD. In particular, when drilling multiple holes, the distribution and fluctuations of the electrolyte flowrate in each channel could influence the uniformity of the electrolyte flowrate among multiple tube electrodes, thereby affecting the machining stability and the maximum feed rate. Thus, an eight-channel flow control system was developed to measure and regulate in real time the electrolyte flowrate supplied into each individual tube electrode. This paper proposes ECD of small holes with real-time flowrate control to improve the uniformity of electrolyte flowrate in each tube electrode and reduce the fluctuations in the electrolyte flowrate. In single-hole drilling, when the electrolyte flowrate was regulated in real time, the hole quality and machining stability were considerably better than without regulation. This is because the electrolyte flowrate remains basically constant, which stabilizes the flow field. Moreover, by considering the hole profile, it was found that an electrolyte flowrate of 200.0 mL/min can be acceptable for ECD of small holes. When the eight-channel flow control system was used in multiple-hole drilling, the uniformity of the electrolyte flowrate in each tube electrode was obviously improved, which led to a more stable process. Additionally, the maximum feed rate can attain 2.40 mm/min in multiple-hole drilling. Based on these findings, a matrix (5 × 32) of multiple small holes was successfully fabricated with a satisfactory diameter consistency, as the machining stability and machining efficiency had been enhanced.