EDM Basics - 2: How it Works
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WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.
Two parts, the mold blank and the electrode, are submerged in an insulating liquid which is called the dielectric fluid. Both are connected to a source of current which can be switched on and off at will. The electrode and mold will be hooked up with opposite polarity (+ or -). When the current is switched on, an electric tension is created between the two metal parts.
As the two parts are brought together the electrical tension becomes great enough to overcome the insulating capabilities of the dielectric fluid and a spark jumps between them. Where it strikes, the metal is heated to a very high temperature, rapidly causing vaporization.

Innumerable such sparks spray, one after the other (never simultaneously), gradually shaping the desired form in the piece of metal according to the shape of the electrode. Several hundred thousand such sparks must fly per second before erosion takes place.

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label: edm, electircal discharge machining, electodes, voltage, dielectic fluids, graphite, wire edm, die-sinking, injection molding