Wire EDM Services

Wire EDM services are not exactly new technology. The concept was originally discovered in the 1770′s by an English Scientist. It was not until the 1970′s that EDM was commercially developed, and in the 1980′s began to be distributed and utilized through the world of machine shops.

Wire EDM (Electrical Discharge Machining) is an electro thermal production process that removes metal in a very precise manner by harnessing the heat of an electrical spark. Precision wire (typically brass) is fed continuously from a spool through precision diamond guides, one above and one below the work piece. As the wire is fed it is energized with electricity. The work piece to be machined, which must be a conductive material, is grounded. The EDM machine moves the wire (or the table holding the work piece) in the path that is to be cut. As the wire nearly touches the work piece, sparks begin to jump between the wire and work piece in an extremely fast, very controlled manner. The sparks are microscopic and each spark removes a very microscopic piece of material. Millions of sparks per second are constantly removing material so that the wire appears to be cutting through the work piece material, leaving a gap or cut path behind it slightly larger than the wire and in whatever path the wire is programmed to move through the work piece material. Dielectric water is fed constantly over the wire and into the gap which cools and flushes out the microscopic melted particles. The used wire, which appears microscopically pitted, is taken up on a spool or chopped into short pieces to be sold to a metal recycling facility.

The most common wire size used in EDM is.010″ diameter. The sparks themselves actually take up space, causing the curf or cut of the wire to be larger than the wire itself. A.010″ diameter wire might leave a cut anywhere from.0106 to.014 wide, depending on the amount of energy used to make the cut. The more energy used to make the cut, the faster the wire travels, and the less precise the cut path is.

Companies offering wire EDM services have a variety of equipment and options to choose from. Mitsubishi, Agie, Charmilles, and Sodik are all major brands of wire EDM machines. Many of these machines will run multiple wire sizes ranging from.0012″ diameter to.012″ diameter. The smaller wire sizes allow companies to do micro machining and very small and complex parts. Wire EDM is capable of producing a wide range of surface finishes. At the rough end of the scale the finishes start around 250 Ra microinch ( μ” ) and by use of multiple trim passes can go down to 4 Ra microinch ( μ” ). Many EDM machines can tilt the wire, allowing them to make parts that have a tapered shape. Wire EDM machines are also capable of cutting and threading the wire automatically, allowing the machines to be programmed to make multiple cuts in a part without operator intervention. A hollow stream of water is shot at high pressure from the top wire guide to the bottom, and the wire is fed down through this stream until the rollers in the bottom head pick up the wire and beginning pulling it. With all of these automatic features built into the machines, companies offering wire EDM services often run their machines at night unattended on long cuts.

Many industries benefit from wire EDM services. The medical and electronics industries both often have applications for micro wire EDM services. EDM machines are often used in the production of extrusion dies, punch dies, and even plastic injection mold work. The automotive, aerospace, defense, textiles, and many other industries all use parts that must be built on wire EDM machines. Wire EDM today has truly become a main stream production process.