In Wire Electrical Discharge Machining, or Wire-Cut EDM, a thin single-strand of metal wire is fed through the work piece, typically occurring while in a submerged tank of dielectric fluid or deionized water. This fluid helps to cool the process and flush away the cut material. The wire cutting process uses electric current to cut conductive materials leaving a smooth surface that requires no further finishing or polishing.
This process is used to cut plates and to make punches, tools, and dies from any conductive material, including hard metals that are too difficult to machine with other methods, such as; metal allows, graphite, carbide and diamond. The wire is held between upper and lower diamond guides. The guides move in the (X-Y) plane controlled by a CNC, the upper guide can also move independently in the (Z-U-V) axis, giving rise to the ability to cut tapered and transitioning shapes and can control axes movements. This gives the Wire-Cut EDM the ability to be programmed to cut very intricate and delicate shapes.
The cutting wire never touches the material, the cutting itself is due to the erosion that occurs when a spark forms between the cutting wire and raw material. A typical Wire EDM process will consist of a minimum of three passes, moving at various speeds. The first passes are typically fast moving, lower accuracy to remove large amounts of material. Later, skim passes, will retrace the cuts at lower speeds, removing less material but improving the surface quality and accuracy of the cut. If complex cut outs are required, a pre-drilled hole through a raw material can be threaded and the machine can begin cutting from there. Applications for Wire EDM include the creation of extrusion dies, blanking punches and metal and tool fabrication.