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Tool electrode wear varying with different materials in electrical discharge machining (EDM) is unavoidable, thus inevitably reducing the machining quality and accuracy of microstructures. To convert this disadvantageous phenomenon into a beneficial process, the paper proposed a wear-variation EDM (WV-EDM) approach to fabricate a laminated disc electrode (LDE) with stable-shape micro channels on the outer edge surface; this electrode was subsequently used to machine micro grooves on workpieces by EDM. The WV-EDM formation of the LDE, the relationship between relative volume wear rate of the disc foils and the machining depth, and flow field distribution in the machining gap of the LDE during processing were investigated. The results show that the method proposed herein could reliably produce LDEs with stable micro channels on the outer edge surfaces that could subsequently be employed to continuously machine micro groove arrays with the same machining depth on the same material workpiece by EDM, and especially LDE reshaping was unnecessary. Additionally, the "pump effect" of the vortex, located in the flow field between micro channels on the LDE and workpiece, was beneficial for debris removal. Using the proposed method, micro groove arrays and columnar microstructures were successfully fabricated on Ti–6Al–4V alloy workpieces. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new method to fabricate tungsten microelectrode instantaneously by means of the pressure difference of plasma between cathode and anode in a single electrical discharge. The influence of main machining parameters, such as electrode material, polarity, dielectric medium, discharge duration and peak current, is analyzed by detailed experiments to obtain the fabricating law of tungsten microelectrode. The fabricating principle is described clearly. As the result of experiments, a tungsten microelectrode about 350μm in length and 30μm in diameter can be fabricated on the top of the tungsten wire of 0.125mm in diameter by this method. At the tip of the tungsten microelectrode, its radius is about 100nm. This method can greatly shorten the microelectrode fabrication time and effectively improve the reliability of the microelectrode. Especially, this method can fabricate a nanometer level tip in general electrical discharge machining (EDM) machine tool and need not add any other apparatus. The fabricated microelectrode can be used as a drilling tool in micro-EDM or a probe for scanner and measurement devices. [Copyright &y& Elsevier]