There are two basic processes used EDM or electrical discharge machining. One is sinker EDM and the other is wire EDM. Both use the same general principles to create a shape in a material, but there are also differences to consider as well.
In all EDM machining, there are three components including the tool-electrode and the workpiece-electrode and dielectric liquid on the material. Between these two electrodes, there is a recurring discharge of current that builds until it builds an electric field that is capable of removing and shaping the material. The liquid, which is used to both cool as well as to remove the micron sized particles of the material, is an essential part of the process.
Wire-Cut EDM History
Wire EDM, which may also be called wire-cut EDM, is a relatively new technology first developed in the 1960s for NC (Numerically Controlled) machines. Originally used for making dies from very hard steel, today it is used for hard and soft materials and is often used because of its ability to create a complex shape with relative ease compared to other types of machining options.
In the early designs of wire-cut EDM the wire was wound on two spools and was constantly wound between the two, preventing areas of extreme wear that would cause the wire to break. With the advancement of technology to CNC machine, the first wire-cut EDM was developed and used in 1976 by David H. Dulebohn and his team working at Andrew Engineering Company.
The sophistication of both the CAD systems as well as the wire-cut EDM machines today allows for an amazing amount of detail and complexity with the system. The material, which is conductive, is placed in a tank of deionized water, which is the most commonly used dielectric fluid.
The most common wire used with most wire EDM machines is brass. As with the original models it is fed in a continual manner during the shaping process and guides that can move across and through the plane keep the wire following the precise shape.
With this full range of movement on both the upper and lower guides across all planes means there is unrestricted movement to develop incredibly complex shapes, multiple shapes on a single piece and complete it all to tolerances that are incredibly tight. Contour tolerances of plus or minus 0.0002″ and hole tolerances of plus or minus 0.0001″ makes this process a choice for many different industries and applications.