Fabricating micro-core by EDM with multi-station narrow slit electrode

Abstract

A method of fabricating micro-core on hard materials by electro-discharge machining (EDM) with multi-station narrow slit electrode was proposed. Instead of changing electrodes traditionally, the method of transforming the electrode station was applied, and the positioning error could be avoided. With the narrow slit structure of the electrode, the discharge debris could be excreted easily and the high depth-to-width ratio of micro-core could be fabricated. NAK80 was selected as the core material, while copper-tungsten alloy (70 % W) as the electrode material to carry out the fundamental experiments in which the relationship between the number of electrode stations and forming accuracy of micro-core was researched. The results demonstrate that using four electrode stations, the dimensional precision is within 3 μm, the root radius is within 10 μm, and the surface roughness is Ra 0.198 μm, and all this can be satisfied with the demand of molding for microfluidic chip. On the basis of the fundamental experiment results, a variable section micro-core was manufactured. The machining results show that the forming accuracy of the convex becomes worse with the decrease of the forming convex height. This phenomenon was analyzed in EDM principle and the error reflection mechanism.