Investigation of the controllable characteristics of electrical discharge ablation of Ti6Al4V

The local excessive ablation of Ti6Al4V by electrical discharge machining ablation (EDMA) is investigated in the present work. In order to achieve the high efficiency and stable ablation machining of Ti6Al4V, a method of diluting the concentration of oxygen medium by the nitrogen is proposed; that is, a mixed gas medium composed of nitrogen and oxygen is used as a gas medium for EDMA. Firstly, the effects of the oxygen concentration, discharge energy, and gas pressure on the excessive ablation of Ti6Al4V are theoretically analyzed. Then, the quantitative correlation between the above three factors and the excessive ablation phenomenon is established through the experimental exploration. Finally, the Taguchi orthogonal method is applied to systematically investigate the effects of the mentioned factors on the material removal rate (MRR) and electrode wear rate (EWR), and compared with the conventional electrical discharge machining (EDM). The experimental results show that the discharge energy and the gas pressure decrease parabolically as the oxygen concentration increases, while discharge current decreases linearly as the gas pressure increases. Moreover, the pulse width decreases exponentially as the gas pressure increases. It is observed that the discharge current and oxygen concentration have significant effects on MRR, while pulse width has significant effects on EWR. The present work shows that the processing efficiency of EDMA is more than 9 times of that for EDM with solid electrode in water.