What is Electrical Discharge Machining (EDM)?


Electrical discharge machining (EDM) is a kind of machining operation employed for shaping conductive workpieces into geometrically complex parts. Electrical discharge machines are particularly well suited for machining components which have complicated contours or subtle cavities that would be difficult to produce with other conventional machining equipment. The process involves supplying electricity to both the shaping tool as well as the workpiece and then bringing the tool into close proximity using the workpiece, that is completely immersed inside a dielectric fluid bath. This proximity causes the electrical field intensity between the oral appliance workpiece to beat the strength of the dielectric fluid, and produces a series of electrical discharges together. These electrical discharges remove material from the workpiece, and the pattern or shape of material removed relies upon the form of the tooling electrode. After the machining operation, the dielectric fluid is replaced between your electrodes. Apart from serving as a dielectric between the two electrodes, the fluid also plays a key role in the machining process, as it is accustomed to eliminate the removed material and funky the machined area. The character from the process is such that, while materials are being taken off the workpiece; the tooling electrode is also gradually eroded, making periodic replacement necessary.

The electrical discharge machining process is extremely precise and usually used in producing components which are typically complex and need extreme accuracy. Additionally, another area of application that EDMs perform above par is incorporated in the machining and shaping of hard or exotic materials for example titanium, Hastelloy, Kovar, Inconel, Taiwan EDM as well as hardened steel. However, the only real caveat with the electrical discharge machining process is it could be only be combined with conductive materials.

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You will find essentially two kinds of electrical discharge machines, which differ in the kind of tooling electrode that they’re outfitted with. They’re sinker EDMs and wire EDMs. The sinker EDM, also known as a ram EDM uses a shaped tooling electrode to facilitate the machining process. This tooling electrode is formed by conventional machining right into a shape that is specific to the application it is used for as well as an exact reverse from the contour around be machined into the workpiece. The tooling, typically machined from graphite, is used with an insulating fluid such as oil or any other dielectric fluids. This shaped tooling is linked to a power supply making to approach the workpiece electrode, creating electrical discharges between them, which cause erosion in the desired shape. This type of EDM is usually used for precise machining of complex 3D parts, such as injection molding, die tooling, and other components that require exceptional accuracy.

The wire EDM, on the other hand, is an electrical discharge machine that uses an excellent metallic wire, usually produced from brass, which acts as a cutting electrode to accurately shape intricate, complex aspects of thick metal plates. The wire and workpiece are generally provided with electricity so when the wire approaches the workpiece, electrical discharges occur between them. These discharges remove material in the workpiece inside a shape that resembles a cutting or slicing action. Because the wire electrode is eroding along with the workpiece, it’s continuously fed into the workpiece from the spool to ensure uninterrupted cutting operation. The wire is fed through two guides, typically made from diamonds, each placed above and below the workpiece electrode. These guides are movable on a 2-axis x-y plane and therefore are CNC controlled for cutting. The cutting operation occurs on the workpiece that’s completely immersed inside a dielectric fluid bath, normally de-ionized water, which is used like a coolant and also to eliminate the removed material. This machining process can be used to cut complex and complicated 2D shapes on thick metal parts, especially components from hard and exotic metals for example Inconel and titanium. Some components commonly machined using wire EDMs are stripper plates, custom gears, along with other parts that need to be intricately cut out. However, the arrival of upper guides and multi-axis freedom of movement in the newer wire EDMs, allows they to chop intricate tapers and transitional shapes too.