Because of the exceptional physical, chemical, electric and mechanical properties of hard and brittle materials, such as ceramics, glass and diamond film etc, those are considerably valued in high technology industry. Although those materials can be machined using the ECDM method, its machining mechanism is still indeterminate. In this study, a static electrical pitting tester is employed, the electrolyte is KOH(eq), the workpiece is glass, and we change the parameters, such as supply voltage, supply current and machining gap to investigate the mechanism of static Electrochemical Discharge Machining. From the experimental results, which are SEM pictures of machined glass and variations of current, we can clearly infer the mechanism of static-ECDM. Moreover, the most important reason for damaging glass is supply voltage. Even increasing supply voltage can make glass cleave. And the main factor to make the loop become insulating is supply current. While the supply voltage is 50V, the supply current is 8A, and in different machining gap condition, the results show that it has a certainly gap to discharge during the machining process, and the particular gap is about 49£gm. The results also show that the machining model has two kinds of types. When the machining gap is shorter than 49£gm, the machining model is from ring to circle; contrarily, when it is longer than 49£gm, the machining model is circle directly.

In the study, a self-developed electrolytic micro-machining tester is employed to investigate the effects of the supply voltage and the highest position of the workpiece relative to the tool on the geometry of the tungsten rod. The peripheral surface of the iron needle (tool) is insulated by an insulator and its tip with a diameter of 50£gm is exposed to the electrolyte as a cathode. The tungsten rod (workpiece) with 200£gm in diameter reciprocates as an anode. Both the cathode and the anode are dipped into an aqueous electrolyte of 2wt % sodium hydroxide to proceed electrochemical machining. Experimental results show that since the length and the diameter of the workpiece are varied during the machining process, it is necessary to manually adjust the highest position and the gap between the workpiece and the tool in each reciprocating motion to achieve a uniform tungsten rod. Moreover, because of the higher removal rate of the workpiece at the higher supply voltage, it is hard to control the geometry of the workpiece. On the contrary, the geometry of the workpiece can be controlled at the lower supply voltage. Finally, the workpiece is first machined at the higher supply voltage, and then the supply voltage is switched to the lower one to achieve a uniform tungsten rod with 2£gm in diameter and 200£gm in length, or 100 in aspect ratio.