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Electrical Discharge Machining (EDM)

Traditional machining methods are not without their limitations. The technology found in electrical discharge machining, or EDM, has proven to be an effective alternative for manufacturing parts that are otherwise seemingly impossible or at least very difficult to machine.

Unlike commonly utilized processes such as casting, forming and other conventional machining processes, EDM achieves high levels of accuracy using digital inputs. The EDM method has applications across several industries such as automotive, electronics, aerospace, medical devices, defense and more.

At its core, EDM is a nontraditional manufacturing process that uses heat from electrical discharge to shape and remove material. It converts an electrical discharge into thermal energy that basically vaporizes material to create a desired shape or outcome. It harnesses the erosion that accompanies electrical discharge to make shapes out of the raw material. It has also been referred to as spark machining.

Also unlike traditional machining methods, EDM is not dependent on the material’s hardness or softness. The only important variable is that the two materials must have good electrical conductivity. Extremely hard materials such as tungsten carbide can be manipulated with ease, and features like sharp internal edges or deep cavities are especially effective with EDM. The entire EDM process is automated with no human involvement.

There are two main parts of the process including the electrode and the material. Each part is connected to one end of the power supply. The material is fitted with the anode electrode, and the other with the cathode electrode. When they become close, a hot electrical spark jumps from the electrode to the material. This will generate temperatures of 8,000-12,000° C in the spark gap. The material melts and erodes. These extremely high temperatures (hotter than the surface of the sun) require the need for a dielectric fluid that controls the spark. It acts as a coolant and cleans away tiny particles eroded during the EDM process.

EDM is a safe custom machining method for producing components with critical tolerances. The EDM process does not vibrate or apply pressure to the material used. There are other advantages and limitations to consider before choosing EDM.

Advantages of EDM include the ability to machine virtually any material that conducts electricity without worrying about toughness, hardness or microstructure. EDM is perfect for cutting extremely hard electronically conductive materials not successfully achieved through conventional methods. EMD provides a good surface finish and touts superior accuracy, tolerance and reproducibility. The process also does not leave any burrs that need removing or toolmarks on the finish product.

Limitations to EDM include the inability to use the process for materials that do not conduct electricity. The material removal rate (MVV) of EDM is very slow, so limiting it to materials that cannot be machined by other conventional processes is necessary. EDM is a highly sought-after process in aerospace and high tech industries.

For state-of-the-art machining and plastics injection molding, The Toolroom is your global source for superior outcomes. Let our expert team of engineers and technicians spark your interest with professional guidance from conception to completion.

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