Influence of Oxidizing Gas on the Stability of Dry Electrical Discharge Machining Process

Due to the absence of a dielectric liquid dry electrical discharge machining (DEDM) can result in comparison to traditional EDM in a simpler and environmentally friendly machine. Driven mainly by this reason several efforts have been made in the past years to understand the erosion mechanism with gaseous fluid and especially with molecular oxygen. The latter is often used due to his enhancement effect on the material removal rate. The effect has been attributed in the literature to the thermal energy surplus resulting from the oxidation of eroded material. This paper presents measurements of material removal rate in function of different flushing gases. Monitoring the voltage and the current values over the erosion gap effective energy specific values of the material removal rate can be calculated. This data shows that the heat energy from the oxidation has only a little effect on the material removal rate and that the main difference between oxygen and less oxidizing gases is to find in different stability and time efficiency of the process. Possible mechanisms driving the observed effects on the material removal rate with oxidizing gases are discussed.