Influence of open-circuit voltage on high-speed wire electrical discharge machining of insulating Zirconia

Insulating zirconia has attracted increasing attention in industrial applications due to its excellent hardness, chemical stability, and corrosion resistance. However, insulating zirconia is difficult to machine by using traditional cutting techniques. In this paper, the high-speed wire electrical discharge machining (HS-WEDM) process of insulating zirconia is carried out with the assisting electrode method. The machining characteristics of insulating zirconia with HS-WEDM process are investigated, which include the study of effect of open-circuit voltage (U) on machining speed, discharge gap, surface roughness, surface microtopography, and electrical discharge status. The experimental results indicate that when U is changed from 90 to 150 V, the machining speed increases from 1.02 to 2.61 mm²/min and the machining gap increases from 15.55 to 26.67 μm. With the increasing U, the percentage of electrical discharge with high resistance increases, the percentage of electrical discharge with low resistance changes only slightly, and the percentage of short circuit with low resistance decreases. Moreover, when grooves are machined into transverse and longitudinal direction of the workpiece, the two machined surfaces of one grove present different surface characteristics.