Journal of The Japan Society of Electrical Machining Engineers

A lathe-type machine for electrochemical discharge machining (ECDM) has been developed for machining axisymmetric parts made from insulating materials. In this paper, the removal mechanism of glass was experimentally investigated by measuring the machining forces with a two-axis force sensor during ECDM. The principal force at an applied voltage of 40 V was larger than that at 0 V while the normal force was controlled. The amplitude of the principal force was increased and the cycle lengthened during ECDM. Soluble and sticky sodium silicate was generated by the chemical reaction of silica glass with sodium ion. This removal process mainly caused dissolution of the sodium silicate into electrolyte.

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We have studied the production process for a polygonal pillar electrode with a copper mask plate and electrical discharge machining of the tungsten material using this electrode. Planetary motion was applied to the mask plate in which a polygonal hole was machined in advance. The polygonal micropillar electrode was produced by this reduced scale process. Zinc alloy, which is easy to form by electrical discharge machining, was used for the electrode material. In this process, the machining conditions under which the wear of the mask plate was small and the forming rate of the electrode was high were chosen. In the next stage, polygonal microholes were drilled into the tungsten material using this electrode. In hole machining with a zinc alloy electrode, the removal rate became higher than that with a same-shape copper electrode. In order to perform simultaneous machining of a microelectrode and microholes, a tandem structure mechanism was developed. Continuous polygonal microhole machining was attained by applying the tandem mechanism.

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