The high electrical and thermal conductivity of copper is combined with the arc-resistant and non-welding properties of tungsten and molybdenum EDM electrodes consisting of highly conductive and / or arc-resistant materials such as graphite or copper. EDM is an acronym for electrical discharge machining, a process that uses controlled electric spark to erode metal. EDM electrodes contain elements made of brass, copper and copper alloys, graphite, molybdenum, silver and tungsten.
EDM enables machining of metal for which traditional machining techniques are ineffective. Works only (except for the specified design) with electrically conductive materials. With the help of repeated electrical discharge, you can cut small, odd angles and detailed contours or cavities in hardened steel, as well as in exotic metals such as titanium and carbide.
Materials for EDM electrodes must have properties that easily enable charge, and at the same time are resistant to erosion, which the EDM process encourages and stimulates in the metals it processes. The alloys have properties that provide different benefits depending on the needs of the application.
Brass is an alloy of copper and zinc. Brass materials are used to form EDM wire and small tubular electrodes. Brass is not wear resistant as well as copper or tungsten, but it is much easier to process and can be die cast or extruded for special applications. EDM wire does not have to provide resistance to wear or arc erosion, because new wire is fed continuously during the cutting process of EDM wires.
Copper and copper alloys have better EDM wear resistance than brass, but are more difficult to process than brass or graphite. It is also more expensive than graphite. However, copper is a common base material because it is highly conductive and strong. It is useful in the EDM machining of tungsten carbide, or in applications requiring a fine finish.
Copper as tungsten are composites of tungsten and copper. They are made using powder metallurgy processes. Copper tungsten is very expensive compared to other electrode materials, but it is useful for making deep gaps in poor flushing conditions and in tungsten carbide erosion machining. Tungsten copper materials are also used in resistance welding electrodes and some applications with circuit breakers.
Graphite provides a cleaning effect at low speeds. Carbon graphite was one of the first brush species developed and is found in many older engines and generators. Has an amorphous structure.
Molybdenum is used to produce EDM wire. It is the wire of choice for working in small gaps and for applications requiring extremely small corner radii. Molybdenum has high tensile strength and good conductivity, making it ideal for applications where small diameter wire is required for demanding applications.
Tungsten silver material is tungsten carbide particles dispersed in a silver matrix. Silver offers high electrical conductivity, and tungsten provides excellent erosion resistance and good anti-welding properties in high power applications. This composite is therefore an ideal choice for applications in ED electrodes where maximum conductivity is crucial.
Tellurium copper is useful in EDM requiring accurate finishing. Tellurium copper has machinability similar to brass and better than pure copper.
When choosing electrode erosion electrodes, the most important factors, in addition to their form and function, are material conductivity (or resistivity) and resistance to erosion.
Conductivity promotes cutting performance because electric current is a "cutting tool".
Resistance to erosion (melting point, hardness and structural integrity coefficient) provides the electrode with a longer life and reduces the frequency of replacement. These properties, which differ almost entirely depending on the type of alloy or material used, must determine the choice of electrode.
Wire EDM (EDM) can cut amazing shapes with precision and very fine finishes. There are many wires to choose from, each of which has its own advantages and disadvantages. Do you need two-tenths or do you want to drive as fast as possible?
Here is a simple explanation of the two basic types of wire.
If you're just looking for a flat speed to pull out some material to put it back on the shelf for another job, a large coated wire .012 ”-. 014 "is your choice. Coated wires have a copper or brass core that is highly conductive, and a thin coating of a combination of zinc and copper. This outer shell protects the inner core, allowing high power settings with increased "on" time for faster material removal.
Another advantage of using coated wires is less wire breakage compared to the same generator settings with a brass wire. The wires are coated in various "types" from A-D. Each type provides specific benefits for each application. Although the biggest advantage is coated wires compared to ordinary brass wire, some coated wires are better in accuracy, finish, poor flushing conditions and materials such as carbide.
Considering all this, the cost factor should also be considered. Although coated wires can achieve cutting speeds 20-30% faster than ordinary brass wire, you need to determine if a higher cost factor is justified.
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