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Posted on Nov 9, 2020
Electrical Discharge Machining or EDM is a process that uses electricity to vaporize metal in a localized area. There are several different types of EDM machines available on the market, and knowing as much about them as possible is the key to choosing the right machine for your needs.
The electrode is electrically charged by servo-controlled generators to produce the spark while the water-based dielectric flows around and through the electrode to create a controlled environment in which the spark can move and enter the workpiece.
The spark erodes the surface of the workpiece, creating very small pockets, millions in number, eventually turning into a tiny hole. Today we are going to tell you a little bit about EDM drillers, their advantages and applications.
EDM drilling works just like any other EDM process, except that the EDM drill is optimized for making semi-accurate holes in tough materials at high speeds - regardless of the hardness of the material. As with other EDM processes, a rinse fluid is required when using EDM drillers to wash the eroded particles off the cut.
To achieve this, it is necessary to bring the flushing liquid to the very bottom of the hole to be cut. This in turn requires a drill electrode that has a through hole - sometimes called a tube - to allow the fluid to continuously and easily pass through the electrode.:: Read more : Drilling EDM & Discharging Process
The main advantage of using EDM drillers is that, unlike regular drills which use physical force to push the tool through the workpiece, it doesn't matter how hard the material is drilled. Whether the material is as hard as diamond or as soft as paper, drilling will be handled almost as easily.
With physical drills, the tool can wear out quickly when drilling into harder materials - which can be less than ideal when you need to quickly drill holes in high hardness workpieces one by one. Drill pipes used in EDM drillers are usually low-cost, high conductivity material such as brass or copper.
This helps keep the cost of replacing worn EDM drill pipes to a minimum. The depth at which the hole can be drilled can be greatly affected by the size of the drill pipe.
Typically, the effective drilling depth of an EDM drill is about 200-250 times the pipe hole size. There are several EDM drillers that can perform 5-axis machining to create holes at different angles for specialized applications.
Typical applications of EDM drillers include removing a broken tap / drill / reamer, wire EDM starting holes, and creating cooling holes in aero engine components - in addition to simply drilling holes for other applications. Some industries that may benefit from using EDM include aerospace, energy, general manufacturing, tools and dies, mold making / repair, and the medical / medical industry.
EDM drilling is in many respects similar to conventional drilling operations, but has the advantages of EDM and workpiece hardness, and very low machining does not limit productivity.
Some of the applications where this component can be used include: adding wire EDM start holes after heat treatment; removal of damaged drills; placing holes that are either too small or difficult for conventional drilling; and coolant holes found in hardened tool tips in machines.
The main criterion for EDM drillers is speed. Common hole sizes range from 0.125 to 0.020 diameter using a single roughing process and typically tolerances of plus/minus 0.002 inch. EDM drillers can be simple handheld or CNC machines that include electrode tool changers and automation.
In EDM drillers, pressurized water flows through the electrode via an additional external water supply hose to remove contaminants. Most machines operate without immersion and use external rinsing lines. However, more advanced machines provide fully submerged operations that improve cycle times, part stability and electrode machining.
There is a specialized category of EDM drillers called fine hole EDM drillers which provide high accuracy in hole size, surface finish and roundness. Hole diameters can range from 0.125 inch to less than 0.001 inch, achieving accuracy of plus/minus 0.0001 inch.
The treatment is performed with high pressure rinsing through the rotating electrode and is usually completely immersed in an oil dielectric. The machining speed is slower than that of water-based EDM drillers, but the accuracy and metallurgical properties have been greatly improved.
These machines often have the ability to perform both EDM drillers and standard downhole EDM operations on a single machine platform.
High Speed Hole Drilling EDM drillers are built for fast and highly accurate EDM drilling applications. Small holes, once nearly impossible to drill with traditional machine tools, are now made with ease. Thanks to the ability to dig into almost any conductive object, the application of this technology is rapidly expanding.
Initially, shops used this technology primarily to create holes in the EDM wire machine. With this technology, workpiece materials are sent for heat treatment before the starting hole is drilled.
This removes two major problems: the need to program, find and drill holes by traditional machine methods in a "soft" workpiece before heat treatment, and by heat treatment of the workpiece before drilling, all stresses are eliminated before drilling. As this process became more widely known, the test firings were not only carried out in hardened tool steel; Tungsten carbide, aluminum, stainless steel, titanium, brass and inconel were tested.
Many EDM drillers use deionized water as an insulating dielectric fluid because it is ten times faster than dielectric fluid. However, the efficiency of electrode drilling for small oil holes is ten times higher. EDM bits with small holes can be operated without immersion, but processing in dielectric fluid is much faster, especially during electrode failure.
You can find many EDM driller manufacturers on imts-exhibition.com. Just head to our product section or check out our search function to find hundreds of suppliers in our product database. If you want to learn more about EDM drilling related questions and applications make sure to check out our other blog entries.
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