Proficiency of Electrical Discharge Machining in Fabrication of Microstructures

Microfeatures have a lot of applications and are widely used in medical, defense, fluidic, communication technology, micro-electromechanical system, etc., wherein machining and fabrication of miniature devices are of prime importance. Electrical discharge machining (EDM) has gained tremendous reputation over the last few decades for its capability to machine electrically conductive material irrespective of their strength and hardness. The variants of EDM such as die-sinking, wire-cut, reverse and milling have proven to be very competent in the fabrication of different kinds of cavities and structures. Nowadays, EDM variants are also highly used in the fabrication of microstructures, which can be credited to the successful downscaling of its discharge energy. Microstructures and microfeatures such as micro-hole, micro-fin, micro-rod, micro-pin, micro-slot with polynomial shape, micro-screw and complex three-dimensional cavity have been successfully fabricated with the use of different variants of EDM. The paper demonstrates the successful use of EDM and its variants in the fabrication of these microfeatures. It mainly focuses on machining of micro-holes by die-sinking EDM, micro-rod by block electrical discharge grinding and reverse EDM, an array of micro-rods by reverse EDM and wire-cut EDM, and micro-fins and micro-screw by wire-cut EDM. The paper also demonstrates the challenges faced and the efficacy with which the various process parameters are chosen to achieve higher machining efficiency and dimensional accuracy in the fabricated microstructures. Finally, the current research trends and the prospects of EDM in the fabrication of microstructures are also demonstrated.