Wire EDM is a type of CNC machining technology capable of unique results. The nature of the Wire EDM process means that you can achieve shapes and structures that are next to impossible with other CNC methods — and can give you incredible results.
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What is Wire EDM?
The theory on which Electrical Discharge Machining (EDM) is based is centuries old. Eighteenth century British Chemist Joseph Priestley observed how electrical charges had removed material from the metal electrodes in his experiments as early as 1770.
With the first functioning EDM machines being developed in the war-torn Soviet Union by physicist brothers the Lazarenkos in 1943, Wire EDM was not far behind.
EDM works by creating an electrical charge that emits sparks. These sparks are incredibly hot, between 8,000°C and 12,000°C. The heat is carefully targeted to melt away metal from a larger metal block and carefully construct the intended design.
The whole process takes place within a bath of deionized water that cools the machine — increasing the water’s resistivity. It also washes away the waste material, a process called flushing.
Wire EDM, also known as Wire-Cut EDM, works in a very similar way, using a rapidly charged conductive metal wire to melt the material. No actual contact is made between the wire and the material, which prevents distorting the path of the wire or damaging the part. Sparks jump the gap and melt away excess metal.
The wire can be highly charged in order to cut away large pieces of material. You can also reduce the machine’s voltage to engineer surface finish. At certain voltage levels, a pass of the wire can remove as little as 0.0001 inches of metal from the surface, removing the rough outer layer creating a smooth and shiny finish.
Wire EDM machines can also move along five axes, including being inclined, to create tapered effects on the metal and offering more degrees of freedom. Wire EDM machines can be rotated on these axes to create tapered indentations and very precise machined cuts.
The remarkable thing about Wire EDM technology is that using this method, it is possible to create certain geometrical features on your piece that are next to impossible with other types of CNC machine. You can create small slots, square corners, and complex shapes and designs within the metal that are impossible with, for instance, CNC milling.
Wire EDM Applications: What is Wire EDM Used For?
While 3D printing is often considered the foremost prototyping technology nowadays, Wire EDM is no slouch in that department. Wire EDM’s production speed makes it incredibly useful for prototyping.
- See also: our guide to CNC prototyping (and how it compared vs 3D printing)
CA Models, a leading prototyping company based in Stirling, Scotland, uses Wire EDM technology as a supplement to other forms of manufacturing to fulfill increasing demands for metal prototypes. Company owner and managing director, Clark Campbell, has publicly stated how, without the Wire EDM technology provided by Sodi-Tech EDM, he would be lost.
These prototypes are highly valuable as few companies offer Wire EDM prototyping. Noting the benefits of wire EDM, cutting-edge industries such as Formula 1 are beginning to use CA Models to produce rapid prototypes with extremely short turnaround times.
Wire EDM is a particularly useful CNC technique for producing parts quickly without any contaminating materials. When producing both medical implants and molds, this is essential.
This needs to be achieved while maintaining a high production speed, as many medical devices and implants are needed in vast quantities, such as orthopedic screws and bolts, joint supports, and implanted splints.
On top of this, tools such as surgical cathodes for syringes, valves for oxygen masks and hand tools are need replacing regularly.
Companies such as California-based Milco Wire EDM are renowned for producing these items using advanced Wire EDM machines, as well as supplying for various other industries too.
Another area in which Wire EDM is used is in the military. Companies like Milco Wire EDM, as well as Owens Industries Inc. are supporting the military through CNC manufacturing, specifically Wire EDM.
Every branch of the military requires a constant stream of high-quality components for both new equipment, and replacement parts for frequently used items and vehicles. Owens Industries Inc. list components for missiles, fighter jets and artillery among their main products.
Wire EDM is capable of producing the best quality parts for these uses, and each must be manufactured with the expectation that it will be used in a life and death scenario. With that in mind, quality and finish is paramount, making Wire EDM ideal.
The Pros and Cons of Wire EDM
Benefits of Wire EDM
Wire EDM has advanced to reach microscopic level cut and indentation accuracy. The technology can be programmed to make cuts mere micrometers thick.
These cuts are also highly repeatable, reducing the risk of deformation or distortion, making Wire EDM one of the most precise CNC manufacturing methods in use.
Similarly, Wire EDM can produce parts with a range of complex shapes and structures. Its five axes and therefore different cutting dimensions mean that it can produce tall, curved, straight and edged parts alike.
This vastly increases the application range of the technology and gives it uses in wide-ranging industries from medicine to high-performance transport and beyond.
Versatility of Production
Wire EDM is versatile in the hardness and conductivity of the metals it is able to cut, giving it applications in a wide array of industries.
Ranging from brass to tungsten, different materials have different compositions and are therefore more adept at producing different products. By switching out different wires, Wire EDM can create a range of finishes with the same machine.
Wire EDM Limitations
Slow for CNC
While Wire EDM is a fast production method when compared to alternative methods like 3D printing, it is not the quickest within the world of CNC.
For anything other than the smallest parts in mass quantities, other methods such as thin-wheel abrasive cutting are recommended for speed.
Wire EDM’s method of cutting using the high temperatures of electrical conductivity means that it can only be used to cut materials that are themselves conductive.
It is incapable of effectively working on materials like plastic or wood that other CNC manufacturing methods can.
Wire EDM’s effectiveness is heavily affected by the environment in which it is working. Minute changes to the composition of the wire, the workpiece, and the ionization of the cooling water will affect its ability to work.
This means that perfect conditions are paramount, and any change in these factors will cause unwanted alterations to the final result, and potentially damage the product.
What is EDM Wire Made From?
There are a wide variety of different conductive metals that are used for making EDM wire nowadays, each with their own benefits, drawbacks and applications.
Brass is an alloy of copper and zinc, and has quickly become the most common EDM wire material in use today. Zinc has a lower melting and vaporizing point than copper, so the higher the saturation of zinc in the alloy, the faster it cuts.
However, there is a balancing act to be had with brass. When approaching 40% saturation, the zinc begins to change state, and the wire becomes incredibly brittle.
What’s more, saturate too much and you reduce threading reliability, so the wire does not feed into the machine as efficiently. Saturate too little, and you not only lose the strength, but the wire is less capable of making tapering cuts.
Coated wires are made using process called electro-galvanization, where a brass or copper wire is coated in a very thin layer of pure zinc or zinc oxide. These wires cut much faster than their pure counterparts and break less often.
They are mostly recommended for fast finishing of products and give a better surface finish with greater integrity. However, they are more expensive than the pure brass or copper wires.
Diffusion-annealing is a way to reduce the harm of zinc oversaturation in the wires. A heavy coating of pure zinc is applied to the wire, which is then annealed in a furnace so the zinc diffuses into the mixture, resulting in a wire that is 50% brass and 50% pure zinc.
These wires have a more reliably high tensile strength compared to brass wires, and are recommended for cutting tall products faster. They also work well where poor flushing conditions are present, and waste material cannot be efficiently removed by the water, and are especially strong when cutting tool steels, aluminum and graphite.
Steel core wires, unsurprisingly, are made of a high-carbon steel core, coated in zinc-rich, diffusion-annealed brass. The steel provides high tensile strength and fracture resistance, while the highly conductive brass provides a high cutting speed.
Steel core wires can have tensile strengths as high as 290,000 psi, herculean compared to brass-based wires which can be as low as 54,000 psi, and are particularly useful in the manufacturing of extremely tall parts, or parts that require perfect straightness.
Tungsten or Molybdenum
Both tungsten and molybdenum wires are not widely used, but provide a number of crucial uses for the Wire EDM industry. Both are extremely strong, with tungsten being the strongest wire material around.
However, they are poor conductors and suffer from slower cutting speeds. Their high melting points also reduce flushing efficiency, which is a vital consideration for industrial Wire EDM operations.
Where they come into their own is in their applications. When brass and zinc wires cut, microscopic amounts of material are left behind on the finished product. In areas such as medicine and the military, this is unacceptable.
The strength of tungsten and molybdenum wires means that virtually no metal breaks off to pollute the part, and makes them the only choice in these sectors.
How Much Does Wire EDM Cost?
The Wire EDM production process is very costly. Alloying copper and zinc for brass and coating or diffusion-annealing takes a lot of investment in equipment, materials and energy. Even then, there is the process of turning the metal into wire.
There are too many variables affecting the price to come up with a solid number, but it is by far the biggest cost associated with the Wire EDM process.
Brass wires are the cheapest at about $1 per kilogram, whereas molybdenum wires cost upwards of $5 per kilogram.
But the amount of wire required means that these costs rack up very quickly. If you decide that Wire EDM is the best choice for you, shop around to find the best price you can.
What is wire EDM used for? ›
Wire EDM is most commonly used in mold and die manufacturing processes, particularly for extrusion dies and blanking punches. EDM can be used in everything from prototypes to full production runs, and is most often used to manufacture metal components and tools.How does a CNC wire EDM work? ›
CNC Wire EDM utilizes a fine, electrically charged metal wire usually made of brass, to cut through the work piece while submerged in a tank of deionized water. The moving wire erodes any conductive material that is within . 0005” of its path, while the deionized water cools and flushes away debris from the cut.How does EDM electro discharge machine work? ›
5.2 Principles of the EDM process. EDM is a thermoelectric process used to remove metal via a series of discrete sparks between the metal and workpiece. In EDM an electric spark is used as the cutting tool to cut (erode) the workpiece and produce the finished part to the required shape.Which wire is used in wire EDM? ›
There are two main types of wire used for the main wire for EDM machine, brass wire and coated wire.What voltage is used for EDM? ›
In EDM, the voltage supplied is approximately 50 to 300 volts because higher voltage is not suitable for high precision machining.Can wire EDM cut holes? ›
If your parts or components require extremely small-diameter holes popped with high precision and accuracy, you need American Wire EDM. With the capabilities to drill blind or through holes as small as 0.010″ in diameter, we offer EDM hole popping services to meet the needs of any industry or application.What materials can wire EDM cut? ›
What materials can be cut using EDM wire? Any conductive material such as steel, titanium, aluminium, brass, alloys and superalloys can be cut using the EDM wire method. With its accuracy, the EDM wire cut technique has become a convention cutting method in all industries.Can wire EDM cut plastic? ›
Virtually any material that is conductive is a perfect one for wire EDM, and it includes all the metals. DEK's wire-cut EDM equipment also can machine plastic, metal alloys, exotic and precious metals. Below are some most common options.What are the two types of EDM machines? ›
- Conventional EDM Machines. Conventional EDM also goes by several other names, such as sinker EDM, die sinking, cavity-type EDM, volume EDM and ram EDM. ...
- Wire EDM Machines. Wire EDM, also known as spark EDM, wire burning and wire erosion, uses a thin heated wire as an electrode.
Some small-hole drilling EDMs are able to drill through 100 mm of soft or hardened steel in less than 10 seconds, averaging 50% to 80% wear rate. Holes of 0.3 mm to 6.1 mm can be achieved in this drilling operation.
What is the difference between EDM and wire EDM? ›
Conventional EDM cannot produce narrower angles or more complex patterns, while wire-cut EDM can be performed. A more precise cutting process allows for more complex cuts. The wire EDM machine is capable of cutting a metal thickness of about 0.004 inches.What are the functions of main elements of EDM process? ›
Principles of EDM
In this process an electric spark is used as the cutting tool to cut (erode) the workpiece to produce the finished part to the desired shape. The metal-removal process is performed by applying a pulsating (ON/OFF) electrical charge of high-frequency current through the electrode to the workpiece.
Remedy CNC Diamond Wire machine.
This machine can Cut carbon, Ceramic, Glass and many other hard to machine materials.
This electric spark produces intense heat with temperatures reaching 8000 to 12000 degrees Celsius, melting/vaporizing almost any conductive material.How do you maintain a spark gap in EDM? ›
The electrode and workpiece are immersed in a dielectric liquid, and a feed mechanism maintains a spark gap of from 0.0005 to 0.020 inch (0.013 to 0.5 millimetre) between the electrode and the workpiece.How thick can you wire EDM? ›
What is the minimum/maximum thickness of metal your wire EDM machines can work with? Our wire EDM machines can work with metal thicknesses anywhere from . 001 to 16 1/8”.Which oil is used in EDM? ›
Description: Idemitsu high quality Electro-Discharge Machine (EDM) oil is specially formulated with synthetic base oil to give unsurpassed performance. This clear transparent dielectric fluid is odourless and non-toxic. Its low viscosity and high flash point helps to promote a safe and pleasant working environment.How long does EDM wire last? ›
EDM wire is sold by the pound and typically comes in an 8-pound spool. Under normal cutting conditions, one spool will last eight to 10 hours of uninterrupted cutting.Can you wire EDM copper? ›
Wire cut EDM hole drilling is fast, effective, and can be used to machine virtually any electrically conductive or heat-treated metal material, including: Bronze. Copper.Is EDM wire reusable? ›
No, the wire breaks down and is not reusable but we do send it to recycling.
Can you wire EDM hardened steel? ›
Wire EDM can cut all metals. In particular, it is used for cutting: pre-hardened die steels, titanium, austenitic stainless steels, tungsten, and molybdenum.What material Cannot use for EDM? ›
2. Which of the following material cannot be machined using electronic discharge machine? Explanation: Wood is a bad conductor of electricity and hence cannot be machined using electronic discharge machine.What is the most common tool material in EDM? ›
Although any electrically good conductive material can serve as an electrode material, considering the essential factors and properties for better application in EDM, graphite has been the most used as a tool material.What material that Cannot be cut using EDM wire cut? ›
Due to the nature of wire EDM cutting — removing material by using rapidly repeating, controlled electrical charges along a strand of metal wire — the method is limited to electrically conductive materials. Therefore, any material that is a composite or coated with a dielectric is not feasible for EDM.How fast can a wire EDM cut? ›
When using standard 0.010" O brass wire you can expect a consistent, reliable wire EDM cutting speed of approximately eighteen to twenty inch}/hour. Unfortunately, the EDM process creates minute chips and debris that can adversely affect the reliability of this transport system.Can wire EDM cut graphite? ›
Can you wire-cut graphite? Yes, your EDM-wire cut machine can cut graphite, however, graphite being brittle needs careful handling and cutting is very slow; also, it will be better to do plain machining of graphite by milling and use your EDM-wire cut machine for machining the intricate profiles.What products are made from wire EDM? ›
- Aerospace Parts and Equipment. Another field of equipment that the wire EDM CNC precision machining process is ideal for is aerospace. ...
- Precision Military Components. ...
- Medical Equipment. ...
- Punch and Dies. ...
- Dental Equipment.
Advantages of Electrical Discharge Machining
Creates complex shapes that would otherwise be difficult to produce with conventional cutting tools. Cuts extremely hard, challenging and exotic materials to very close tolerances for high precision mechanical components.
Machining time is too long. Excessive tool wear. High specific power consumption.