Abstract
In electrical discharge machining (EDM), the complex discharge phenomena occurring in the gap are difficult to be clarified, and remain to be studied. In this study, light intensities radiated from the plasma which are considered to reflect the material removal behavior were measured under different machining conditions, and simulation was conducted in order to clarify the machining phenomena occurring in the EDM gap. It was found that plasma expanded in a rapid speed within extremely short period of time right after dielectric breakdown and remained constant with the diameter of about 20um after that.
