Wirecut EDM (Electrical Discharge Machining) is a thermal machining process. Sparks discharged from a small-diameter, tensioned wire erode the workpiece without any contact between the tool and the part produced.

This process, also called traveling-wire EDM, produces a straight, narrow-kerf cut. The slowly moving wire brings a fresh, constant diameter electrode to the cutting gap, thereby enhancing kerf size control. Usually a programmed or numerically controlled motion guides the cutting, while the width of the kerf is maintained as a constant by the wire size and settings on the spark discharge controls.

The dielectric is deionized water under pressure, introduced through concentric nozzles at the top and bottom of the workpiece. In a wirecut EDM system, the wire feeds from a spool, travels over tension rollers, along upper and lower guides, over electrical contacts and into a takeup reel. Note that the EDM wire must be threaded through a starter hole in the workpiece. These holes are normally created for the wire by drilling before parts are hardened.

As the wire discharges sparks for thermal machining, the table on which the workpiece is mounted moves to generate X and Y coordinates. Here, small pulse increments (on the order of .00004″) assure accurate cutting. For tapered cuts, some wirecut EDM machines use U and V axes on the upper wire guide. These axes can be used to generate tapers up to 30 degrees per slide. Wirecut EDM can be up to a five-axis process.