The schematic diagram of the experimental setup of EDM for non conductive ceramic with the AE is shown in Fig 1.
The machining has been conducted using NC die-sinking EDM machine (EX22, Mitsubishi, Japan). In the present
experiments, 92% pure ZrO2ceramic plate (20 mm x 15 mm x 10 mm) is used as workpiece. The properties of the
workpiece material are listed in the Table 1. The copper tool electrode (3 mm x 3 mm) is used. The workpiece and the tool
electrode were cleaned by acetone before machining. Since the workpiece is electrically nonconductive, its surface is
covered by an adhesive copper layer to occur the sparks. After the removal of this external layer, a new conductive layer is
created instantaneously on the machined surface using cracked carbon combined with the debris of tool electrode material.
This layer acts further as an assisting electrode. Copper foil has excellent electrical conductivity and easy to remove after
machining without any damage. After machining, the workpiece is cleaned again by acetone before weighing. Electronic
balance (B204-S Mettler Toledo, Switzerland) is used to take the weight of workpiece before and after the machining. The
important machining parameters used in the experiments are summarized in the Table 2. To investigate the effect of input
power in EDM of nonconductive ceramics, experiments are done varying the input power keeping other parameters
constant.