Electrical discharge machining Inconel 718 with adaptively regulating gap servo-voltage

It is well known that it is hard for convention machining techniques to cut Inconel 718 because of Inconel 718 mechanical properties. Electrical discharge machining (EDM) has two remarkable properties. One is that it can machine any electric conduction material; the other is its noncontact machining which generates no forces in machining. However, the Inconel 718 properties have caused a contradiction in machining Inconel 718. The high melting point of Inconel 718 requires using large EDM discharging energies, while low thermal conductivity restricts the use of large discharging energies because after a series of pulse discharging, the temperature rises so fast to make the deionization of the liquid incomplete, the consequence of which could give rise to generation of arcing pulses which make the machining unstable. To solve this contradiction, this paper first proposed to use variance of machining states to be an index to reflect the difficulty of machining any kind of material. Then, machining state expectation was used to balance machining stableness and machining efficiency. Finally, an adaptive gap servo-voltage control system was constructed where gap servo-voltage was regulated so that machining states could follow the machining state expectation in machining. In this way, the contradiction could be solved, and the verification test in experiment proved this fact.