Effect of technological parameter on the process performance for electric discharge milling of insulating Al2O3 ceramic

Engineering ceramics have been widely used in modern industry. However, the manufacture of ceramic blanks is not an efficient process. The shaping of ceramic blanks with conventional machining methods (such as grinding), is a long, labour-intensive and costly process. Wire electric discharge machining (WEDM) is able to effectively slice conducting ceramics. Electrical discharge machining (EDM) and electrical discharge grinding (EDG) of conducting ceramic show lower cost. With the help of some assisting methods, WEDM, EDM and EDG can be used to machine insulating ceramics. However, EDM and EDG of a large surface area on insulating ceramics show lower efficiency. This paper presents a new process of machining insulating ceramics using electrical discharge (ED) milling. ED milling uses a thin copper sheet fed to the tool electrode along the surface of workpiece as the assisting electrode, and uses a water-based emulsion as the work fluid. This process is able to effectively machine a large surface area on insulating ceramics. The machining principle of the process is introduced. The effects of tool polarity, peak voltage, rotational speed of tool electrode and feed speed of workpiece on the process performance have been investigated.