What is EDM? EDM is an acronym for Electrical Discharge Machining. It’s a manufacturing process sometimes referred to as spark machining, burning or die sinking. In this process, a desired shape is created by using electrical discharges or sparks.
EDM is a machining method primarily used for pre-hardened steel and alloys such as Hastelloy, Titanium, Kovar and Inconel. EDM typically works with materials that are electrically conductive. EDM can cut very detailed contours or cavities in pre-hardened steel without the need for heat treatment to soften and re-harden them.
There are two types of EDM. First is Sinker EDM, also called cavity type EDM or volume EDM. This is often used in the making of Dies and Molds. This EDM consists of an electrode that has been configured to a specific geometry. Two metal parts are submerged in an insulating liquid such as oil and are connected to current. The power supply generates an electrical potential between the two parts. As the electrode comes near the work material, electrical breakdown or dielectric breakdown occurs in the fluid. Numerous small sparks occur sequentially causing eroding of the material into the pre-configured geometrical shape.
Second is Wire EDM, sometimes referred to as Spark EDM. This type of machining is an electro thermal production process which creates an electrical discharge between a single strand of thin wire using, again, a dielectric fluid (commonly de-ionized water) allowing the wire to cut through metal material by using the heat from the electrical sparks. The water also flushes away debris from the cutting area. Wire EDM allows the operator to work with harder material while maintaining precision and exactness in the cutting.
Although EDM is primarily used in the Mold and Die Industry, in the past several decades it has expanded to the automobile, electrical and aerospace industries to name a few. It is commonly used in prototyping and has great benefits due to its ability to create complex shapes, work with hard material and hold close tolerance.