What is Wire EDM? (Electrical Discharge Machining)

Introduced in the late ‘60’s, wire-cut EDM was a unique, breakthrough technology. Although it has earned respect for its ability to machine difficult workpieces with unsurpassed accuracy, the machining process didn't gain the full attention it deserves until recently. Its use spread quickly as its accuracy and effectiveness became apparent. Since then, wire-cut EDM has experienced explosive growth; in application, sophistication of equipment, and in the demands made on the basic tool of the process, the wire.

EDM is a machining process used mainly for producing dies, molds and certain metal parts.  Molds and dies are the names given to the production tools that serve to make large numbers of items that are found in everyday use. EDM can also be used to produce finished parts, such as cutting tools, parts cut from solids, and items of complex shape.

EDM is a no-contact and no-force process, it is well suited for making frail or fragile parts that cannot take the stress of standard machining, it can cut parts 16 inches tall with a straightness of ±0.0005 inch per side! Parts requiring small inside radii are now easily achieved using this technology.

Wire EDM, the technology

The work piece and the wire represent positive and negative terminals in a DC electrical circuit, and are always separated by a controlled gap, constantly maintained by the machine. This gap must always be filled with a dielectric fluid, in this case deionized water, which acts as an insulator and cooling agent. Of equal importance, it flushes away the eroded particles from the work zone. Sparks are formed through a sequence of rapid electrical pulses, generated by the machine’s power supply thousands of times per second. Each spark forms an ionization channel under extremely high heat and pressure, in which particles flow between the wire electrode and the workpiece, resulting in vaporization of localized sections The vaporized metallic debris created by this process, from both the workpiece and wire material, is subsequently quenched and flushed away by the flow of dielectric fluid through the gap. As the machine advances the wire through the workpiece, it cuts a slot slightly larger than the wire diameter. Since the wire is also eroded away and used up in this process, the machine constantly feeds new wire into the cut as “fresh” electrode material.