Wire EDM machining is a process used in manufacturing where a desired shape is made by using an electrical spark. It is one of the most accurate processes available for the creation of simple shapes inside other parts. Excess material is removed by sending a rapidly occurring spark through a charged wire, thus making cuts. As the distance between two electrodes is made smaller, the electric field intensity becomes greater in strength, which causes the current to flow. The whole part is immersed into electrical conducting liquid which allows for the wired to react to the current thus cutting any material between the two conductors.
The main wire EDM process we use today was invented by two Russian scientists in the 1940’s. However the first CNC wire EDM machine was not developed until the early 70’s. This technique of machining was created for the purpose of dealing with extremely hard and dense metals where others methods are extremely difficult and damaging to equipment. EDM is often considered to be a non-conventional method of machining with the likes of electro chemical machining, waterjet cutting and laser cutting.
A single thread of brass wire is fed through the piece and submerged in a tank with de-ionized water. Wire EDM can be used to cut hard metals reaching a thickness of 300 milli meters. The water serves as a conduit for the electrical current and also helps flush left over material away from the cutting area. EDM is widely used in the mold, die and tool making industry. It has most recently become popular in the prototype and production part areas especially with the electronics and aerospace fields where production quantities are low.
The cutting pattern is computer controlled. Many wire EDM electrodes can rotate about 3 axis allowing internal cavities to be removed; this makes EDM an extremely diverse system. If a particular job calls for a ‘cutout’ a hole must first be drilled into the material to allow for the wire to enter and complete the machining. This type of machining is gaining popularity due to its effectiveness and ability to remain well inside tolerances. EDM can handle a wide variety of jobs dealing with the production of medical, surgical and dental equipment. EDM can also handle die components, mold, electrodes and large work pieces. If you have a job that requires the utmost respect for tolerance and deals with hard material you might want to investigate this fascinating and efficient technology.
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