Abstract
Machining mechanism of eletrical discharge machining in deionized water with graphite electrode is experimentally analyzed, investigating crater shape by a single discharge, electrode wear, elementary analysis of machined surface and so on. Main conclusions obtained in this study are as follows:
(1) Specific resistance of water for electrical discharge machining in water is required to be more than 106Ω·cm.
(2) Melting volume produced by a normal polarity single discharge is considerably large as compared with that by reverse polarity.
(3) Normal polarity EDM leads to larger machining rate and larger electrode wear under the same machining condition. Electrode wear in reverse EDM is smaller than that in normal polarity EDM under the same machining rate.
(4) The surface of graphite electrode in reverse polarity EDM is covered with melting workpiece material, while there is no phenomenon like this in the case of normal polarity EDM.
(5) Normal polarity EDM is recommended for improvement of surface quality with a specilal electrode or machining fluid.
