Monopulse Electrical Discharge Machining Ablation Drilling Technology for Ti-6Al-4V Titanium Alloy

A high-current monopulse electrical discharge machining (EDM) discharge ablation technique (i.e., monopulse EDM ablation) to drill Ti-6Al-4V titanium alloy plates is proposed. The activated surface material that employs discharge energy as induced energy induces a dramatic combustion reaction with oxygen. Perforation under the monopulse discharge effect is achieved depending on ablation energy produced by the metal oxidation reaction. A system with a monopulse generator is established to perform a monopulse EDM ablation drilling experiment on Ti-6Al-4V titanium alloy. The mechanism is analyzed. Mechanism analysis indicates that the process of monopulse EDM ablation drilling generally has five stages, namely, monopulse discharge and formation of the activated area, violent oxidation of the discharge point, oxidation hindered by the oxide layer, transmissible ablation extension, and downward ablation layer by layer. Tests of via holes are performed to compare EDM drilling and monopulse EDM ablation drilling. Results show that perforation is achieved at 500 μs by monopulse EDM ablation drilling for a 10-mm thick titanium alloy plate. However, the machining efficiency of EDM drilling is low (the machining time is 160 s) and cannot meet the value required by high-efficiency machining. The technology can be applied to cutting Ti-6Al-4V titanium alloy plates.