Influence of Working Surface Temperature on Area Effect in Electrical Discharge Machining Process

Abstract

In this paper, we discuss the effects of working surface temperature on the material removal rate and tool electrode wear rate in sinking electrical discharge machining (EDM) process in order to clarify machining phenomena referred to as the area effect. First, the material removal rate, tool electrode wear rate and effective discharge frequency were measured for a 5mm-square rod tool electrode, and measured results were compared with those for 10mm-square rod tool electrode and 15mm-square rod tool electrode. Although the area effect is conventionally explained as the effect of discharge frequency, the measured results could not be explained in terms of only the dischargef requency. Then, the material removal rate and tool electrode wear rate for butt machining were compared with those of sinking machining, and the working surface temperature of the tool electrode were estimated using the measured temperature. It was found that the material removal rate and tool electrode wear rate are affected not only by the discharge frequency but also by the working surface temperature. It was also found that the tool electrode wear rate in a small working area can be reduced by lowering the working surface temperature.