The factors which make titanium alloy difficult to EDM are experimentally investigated, analyzing the shape of crater generated by a single discharge, the pile-up time of workpiece, the waveform of successive discharge current, the shape of debris and so on. Then the condition for high efficient electrical discharge machining of titanium alloy is recommended. Main conclusions obtained in this study are as follows:
(1) The pile-up generated by a single discharge in titanium alloy is higher than that in steel, and the pile-up time is also longer.
(2) The removal volume of crater generated by a single discharge in titanium alloy is larger than that in steel, which agrees with the conventional theory that the lower product of melting point and the thermal conductivity of material leads to easier EDMing.
(3) The metal removal rate is lower and the electrode wear is larger for titanium alloy under the conventional EDM condition as compared with those for steel, since the frequent short-circuit results in the unstability of machining.
(4) High efficient and low electrode wear electrical discharge machining of titanium alloy is possible by decreasing the duty factor, since the resting duration is enough for pileup of workpiece and the machining becomes stable.