Research on efficient electrical discharge machining trepanning technology of TC4 titanium alloy hole

Owing to low machining efficiency, poor machining accuracy, and surface quality in traditional electrical discharge machining (EDM) of TC4 titanium alloy holes, an EDM trepanning method was developed using a deionized water medium and a flushing liquid in tube electrodes (denoted by EDM-TFD). Several experiments and research mechanisms were conducted on EDM-TFD. Compared with traditional EDM, ED milling, and EDM trepanning, EDM-TFD featured increased hole machining efficiency by more than five times, improved machining taper by more than 57%, and improved surface quality by more than 40%. The optimal processing technology was determined through process experiments using copper tube electrodes, a flushing liquid with a speed of 2 m/s, pulse width (T_on) of 150 μs, pulse interval (T_off) of 150 μs, and peak current (I_p) of 15 A. Under the optimized process, the hole exhibited a feed rate of 1.1 mm/min, machining efficiency of 38 mm³/min, machining taper of 40 μm, and surface roughness of 5.2 μm.