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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]

Micro-electro discharge milling (micro-ED-milling) with simply shaped electrode is highly regarded as a capable approach of machining 3D micro-structure because of its special machining mechanism and the variety of machinable materials. However, a specific CAD/CAM system is needed for generating tool path and related machining process. Due to nature of machining mode and tool electrode geometry, some vestige always remains on the machined surface during ED-milling of 3D structure especially on the complex surface which cannot be expressed with normal equations. To solve the problems of residual vestige, a slicing strategy for micro-ED-milling is proposed. The way of the tool path generation and the algorithm for smoother surface are studied systemically. Meanwhile, with the way of isoparametric interpolation, the machined freeform surfaces of lamination are significantly improved. As a result, some typical 3D structures are machined for verification, including an embossment of a human face within a circular area of 1 mm in diameter. [Copyright &y& Elsevier]

Micro wire electrical discharge machining (micro-WEDM) provides a promising alternative for micro gear machining. However, the processing defect of non-intact tooth profile often appears due to the influence of micro gear gravity, flushing force and explosive force in micro-WEDM process. This paper presents a process change of micro-WEDM to achieve the precise fabrication of micro gear with intact tooth profile, i.e. firstly reserving a sharp corner on the gear teeth where the processing defect exists and then removing it by the second processing of micro-WEDM. The locating and clamping of the micro gear with sharp corner has been achieved using a novel self-centering flexible fixture. The machining error during the second processing is analyzed, and whilst the process datum is accurately determined. Appropriate processing parameters are obtained by performing preliminary experiments on X153CrMoV12 workpiece, indicating that high open voltage and discharge capacitance cause large kerf width, moderate reference voltage and feed rate lead to narrow kerf width. The static contact between the core jig of the fixture and the micro gear with sharp corner is theoretically analyzed using ABAQUS software and experimentally proved to be in good condition. To verify the feasibility and repeatability of the proposed approach, five micro gears with 10 gear number, 0.1 mm module and 2 mm tooth width are machined using 50 μm diameter wire electrode, exhibiting excellent conformity, machining error with less than 1.5 μm and surface roughness Ra with 0.9 μm. [ABSTRACT FROM AUTHOR]