Electro-discharge machining (EDM)

A machining process which uses an electric discharge from a tool (usually brass or carbon) to remove material. Because the tool does not contact the machined part, fragile parts can be machined without distortion. The tool can be a continuous wire, which allows machining of slots. Details ...

Compared to conventional machining electro-discharge machining has two disadvantages —

1. It is relatively slow.
2. It can leave high residual surface stresses and pitting, which, if not removed, can significantly reduce the fatigue life of the resonator.

Also called EDM-ing, electro-spark machining, or electro-arc machining.