All About Wire EDM Machining: Definition, Application, and Materials

The wire used in an EDM machine comes in various grades and purposes. Among the choices are: copper, brass, tungsten, molybdenum, coated (zinc-coated and diffusion-annealed), and steel-core wires. The wire acts as the EDM device’s cutting tool. Each type of wire affects the machining process in different ways. 

Whatever the wire type, it can only be used once and has only scrap value after use. The material breaks down during the electrical discharge process. EDM wire is sold by weight and classification. Its handling makes the difference between an optimized setup and one that is disrupted by breakages, poor precision, or other production interruptions. 

What Kind of Materials Can Wire EDM Cut?

Wire EDM can cut all metals. In particular, it is used for cutting: pre-hardened die steels, titanium, austenitic stainless steels, tungsten, and molybdenum. Though functional, it is generally not cost-effective to cut soft materials such as: copper, bronze, brass, and non-hardened steel, all of which can be easily machined by cheaper conventional means. However, if the part must be manufactured in a single stage or with no added heat, EDM is the only practical option.

What Is the Cutting Method Used by Wire EDM?

Electrical discharge as a machining process uses a discharge (spark) between a tool electrode and a material billet to be cut. The spark energy is dissipated as heat at a microscopic point, reaching as high as 12,000°C and vaporizing both parts. However, since the point of contact is so small, the part does not absorb much of that heat. Wire EDM preserves the electrode by moving the wire through the cut area so the cut is always facing fresh wire. The wire is moved across the workpiece – usually in the X-Y plane – following a CNC-controlled path that is programmed in G-code.