Effect of Mixing Gas for Machining Surface Property of Micro-bubble Entrained EDM.

Electrical discharge machining (EDM) is the process of removing a material by means of electrical discharge inside an insulating working fluid. The material is melted by the discharge and is blown off by the vaporizing explosion of the working fluid. Expansion and contraction of the insulated fluid bubbles affect the process of removing a material. The stronger the vaporizing explosion, the larger is the quantity of material removed and the worse is the surface roughness, and vice versa. The power of the vaporizing explosion is determined by the input energy and quantity of material removed is determined by the power of the vaporizing explosion. Recently, there have been some studies on micro bubbles that are 50 μm or less in diameter. Micro-bubbles possess special characteristics, such as an increased interior gas pressure and increased ion concentration around the gas–water interface. We considered changes in the characteristics of EDM by using a fluid mixed with micro bubbles. The vaporizing explosion was considered to be weakened by using fluid containing micro-bubbles, and the surface roughness seemed to improve Therefore, we performed EDM using pure water and micro-bubble mixed fluid, and researched the characteristics of EDM. Initially, We were expecting a change in the machining removal rate. Indeed, in oil dielectric fluid, there was no change, and there was little difference with the machining rate achieved using pure water dielectric fluid. However, a clear difference was observed in terms of the skewness (Rsk) of surface roughness. In this paper, this difference is described as a change in surface roughness in micro-bubble mixed EDM. [ABSTRACT FROM AUTHOR]