Journal of The Japan Society of Electrical Machining Engineers

Show abstractHide abstract

In this study, we aim to obtain the quantitative relation between debris concentration and gap width in sinking electrical discharge machining (EDM). To simulate the machining accuracy of sinking EDM, it is necessary to determine the discharge location where the dielectric breakdown strength is lowest in the gap. The discharge location is determined on the basis of the fact that the dielectric breakdown strength of the gap decreases with decreasing gap width and increasing concentration of debris particles suspended in the dielectric fluid. Hence, the relation between debris concentration and gap width was obtained. The distribution of the debris concentration in the radial direction of a circular working area was obtained by simulation, and the gap width distribution in the same direction was measured experimentally. Thus, by correlating the debris concentration with the gap width at each radial position, the relation was obtained. The gap width was expressed as an exponential function of the debris concentration whose index was lower than unity.

View full abstract

Download PDF (3454K)

Micromachining technologies have been developed to enhance functionality in limited space and to save materials and energy. Micro-electrical discharge machining (EDM) is one of the micro processing methods. The machining efficiency, however, decreases as hole depth increases because the discharge phenomena become unstable owing to sludge stagnation. In this paper, we propose a new EDM method that applies ultrasonic vibration in machining fluid. Cavitation generated in a hole does not only break down air bubbles in EDM but also quickens the sludge removal. The EDM characteristics in terms of parameters such as machining rate, aspect ratio, and hole appearance are investigated in comparison with those of conventional EDM. The machining rate and aspect ratio rise by a factor of about 2 and the electrode wear ratio is about 2/3 the conventional value in the micro-EDM of sintered carbide.

View full abstract

Register with J-STAGE for free!