Electro Discharge Machining [1] is considered a non-conventional process. It consists of removing material from a part by the repetition of electric discharges (produced by electric pulse generators with very short pulses)  produced between an electrode (the tool) and the component, surrounded by a dielectric fluid that cools and cleans the produced debris (eroded material which is ejected as small spherical particles).

The Electro Discharge Machining was one of the pioneering non conventional processes applied by the industry. It is usual to refer the process as EDM, SEDM for sinking EDM and WEDM for Wire EDM.

Nowadays, the process is usually applied by the industry for high precision machining of electrical conductive materials like metals, metal alloys, graphite or ceramics (whatever the hardness value presented).

Basically the process has two different versions: die sinking and wire electro discharge machining. In the former type of process, sinking EDM, the shape of the applied tool (electrode) is reproduced on the component; in the latter version, wire EDM, a metal wire (electrode) is used as a band saw to cut the programmed pattern on the part.

The negligible value of the process forces and the low unit removal rate per spark (UR) indicate that the EDM process is suitable for the machining of small details in big parts or the machining of miniaturised components.

Some of the latest advances in the field of EDM (both sinking and wire EDM) are directed to the production of details with micrometric dimensions in high precision components. For sinking EDM at the miniaturised scale, it is usual to use the term microEDM, while the WEDM at micro scale is referred as “ultra thin WEDM”, “thin WEDM” or “micro WEDM”.

The present document presents basically the EDM principle, the history of EDM, differences when scaling the process and the latest advances in the field of micro electro discharge machining,

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