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Electrical discharge machining (EDM) is a method that removing material by pulse discharge between the workpiece and the electrode. The surface after EDM would leave discharge craters, the size of the crater and the surface morphology are close related to the processing parameters. Beryllium copper alloy material is used, we focus on the surface after EDM treatment. The height of the surface is measured, and the datum are used to analyze the characteristic amplitude data. Then relationship between the surface topography and the EDM parameters are established. calculating the fitting frequencies and amplitudes of the surface, and the surface reconstruction is realized. Establishing the feature model of the surface, then simulate analyzing the velocity distribution of the fluid on the EDM surface by Fluent software under different machining parameters to investigate the drag reduction performance. The results are verified by real test experiment. This simulation study expands the EDM technology in engineering production for the drag reduction application. [ABSTRACT FROM AUTHOR]

EDM is an effective method for deep and narrow slot machining. The high aspect ratio blind slot can be machined with jump motion and vibration assistance. The decrease in machining accuracy and actual depth caused by electrode consumption in this process are currently common problems. Using oil-based working fluids, graphite electrodes have different wear and deposition patterns under different conditions. This study aims to control the final geometric accuracy of deep and narrow slot machining by optimizing electrical parameters. Experiments using orthogonal design were conducted with a 20×1×20mm narrow slot. The combined influences of parameters on the electrode geometry evolution are concluded. The peak current and duty factor are the main factors affecting the pattern of electrode tip geometry. Experiments were carried out to analyse the wear pattern corresponding to different levels of these two factors. The locations where deposition and wear are prone to occur are found to be the edge of the electrode tip. Parameters combinations capable of stably maintaining the shape of the electrode end are found. The results showed the feasibility of adjusting the tip wear pattern. Thus the final geometric precision of the slot machining can be controlled by adopting apposite parameters. [ABSTRACT FROM AUTHOR]

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]