The consumed wire spools are purchased on pre-wound reels that can vary in capacity, but 11- and 22-pound spools are the most common. 1 Schematic representation of the basic working principle of EDM process. The wire travels through the workpiece (where EDM machining occurs) being guided by two precision alignment wire guides and is then routed into a collection basket in the rear of the machine. Reliable operation of Wire EDM machines is strictly dependent on several operational maintenance items. There is a physical limit to how much power can be applied to and sustained by any given wire size before the wire (think of it as a small filament) melts, breaks, or fractures. “If you tried to mill them, have you to have it held tight enough that your machining process won’t pick it up or bend it. However, the solutions to the material issues in these cases lie in variations of electrode materials and slower EDM cycle times. Work material to be machined by EDM has to be electrically conductive. Both the wire and workpiece sit beneath a layer of dielectric fluid. ), Cabin brackets for the Airbus A350 XWB with support structure. Hole popper EDM can also be used to create the pilot hole necessary for wire threading. The dielectric fluid acts as an electrical insulator unless enough voltage is applied to bring it to its ionization point, when it becomes an electrical conductor. The most common size range is from 0.004” to 0.012” Ø (0.100~0.300mm), and the most widely used wire size is 0.010”Ø (0.250mm), but there are some machines that are capable of operating with wires as small as 0.0006”Ø (0.015mm). ), EDM accessories and consumables (Image courtesy of MC Machinery.). A 1-pass process typically achieves a tolerance of ±0.001 (±0.025mm) and a surface roughness of 120µinRa (3.0µmRa), a 2-pass process achieves tolerances of ±0.0005” (±0.012mm) and a surface roughness of 70µinRa (1.8µmRa), and a 3-pass process achieves tolerances of ±0.0002” (±0.005mm) and a surface roughness of 25µinRa (0.6µmRa). Like a chain being only as strong as its weakest link, Wire EDM machines are only reliable as the amount of maintenance that is performed. Most machines support taper angles up to 15 degrees, but there are special wire guides that allow angles up to 45 degrees. If you’ve enjoyed this third lesson in our 6-part Back to Basics series, be sure to stay tuned for future segments as we reflect on our industry and celebrate the building blocks that have led us to the fascinating EDM advancements that we encounter each day. Older or less-efficient machines will consume over 1 lbs. Conventional wisdom suggests that wire EDM is only competitive when dealing with expensive and difficult-to-machine parts. For example, EDM is typically slower than other machining methods, but it also tends to be more predictable, accurate and repeatable. 82 oete EDM andoo oients o eiaeEDMco Wire Path A. Wire EDM machines also entail other consumable wear items that require periodic replacement and care such as filters, DI resin, wire guides, energizer contacts, rollers and bearings, as well as additional items. Wire EDM machines use a small, traveling wire electrode to machine complex shapes, which are always through cavities (the wire must pass completely through the workpiece). The resulting spark discharge erodes the workpiece to form a desired final shape. In practical terms, electrical discharge machining overcomes a major issue found in contact machining: hardness. Privacy Policy. Wire EDM machines are capable of operating with a range of different wire diameter sizes. of wire per hour running 0.010” Ø. That’s where the similarity with conventional machining ends, however, because in EDM processing, the wire never touches the workpiece. All. Deionized water serves as the dielectric in a Wire EDM just as oil serves as the dielectric in a Sinker EDM. Wire cut EDM (or WCEDM) discharges the electrified current by means of a taut thin wire, which acts as the cathode and is guided alongside the desired cutting path, or kerf. See Figure 1:1. As workpiece materials become harder to machine by conventional methods or the detail size becomes small with higher L:D (length to diameter) ratios, Wire EDM becomes a more attractive method of machining. “Generally, workpieces are mounted on a pallet system and the automation changes the pallets in and out of a chuck on the machine,” said Langenhorst. The more conductive particles in the fluid, the more difficult it is for the machine to maintain stable electrical thresholds inside the sparking gap. If you need to do die tryouts on a form die, you can actually cut the sheet metal blanks to test the form die.”. Electrodes are typically manufactured by milling, but can be also be machined with Wire EDM depending on geometry detail. From a maintenance standpoint, the key difference with Wire EDM Maintenance is that it is performed as a proactive and preventive measure before the machine encounters a failure. Wire EDM machines are capable of operating with a range of different wire diameter sizes. Stark, Harding and Beaver continued to refine their process, which eventually became the basis for the vacuum-tube EDM, which made it possible to increase spark frequency from 60 times per second to well over 1,000. At nearly the same time, an American engineering team—consisting of Harold Stark, Victor Harding and Jack Beaver—was working on a way to remove broken drills and taps. Machines are capable of cutting and re-threading the wire automatically, which greatly extends unattended machining time. But this is not the case. Wire EDM produces a smooth finish because the wire electrode goes through the entire part, and spark erosion occurs along the entire wire electrode. The workpiece setup in a Wire EDM requires that the part be suspended out within the confines of the work zone. Generally speaking, however, the principle characteristics of electrical discharge machining should give you a sense of whether EDM is a good fit for your application. Known by many other names, including spark machining, arc machining and (inaccurately) burning, the EDM process is conceptually very simple: an electrical current passes between an electrode and a workpiece which are separated by a dielectric liquid. “The biggest bottleneck to overcome with EDM processing is managing part throughput by maximizing the unattended operation and overall machine utilization,” he said. Of course, some electrically conductive materials still don’t play well with EDM. If you need to rough cut a lot of parts quickly, electrical discharge machining probably isn’t the right process for you. (It should be noted that Langenhorst did point out that you can use wire EDM to cut shims by stacking the stock, sandwiching it between two pieces of quarter-inch steel, and cutting off a stack.) It is probably the most exciting and diversified machine tool developed for this industry in the last fifty years, and has numerous advantages to offer. By design, Wire EDM machines are electro-mechanical systems that require precise function of all components to be productive. The most popular machine size provide a 14” x 10” X/Y stroke with an 8”~10” Z-stroke capacity, and support part weights in the range of 1,000~1,500 lbs. The maximum part size that can be machined by Wire EDM is dictated by the capacity of the X/Y/Z strokes, the size of the work tank, and the weight capacity specifications of a particular machine. The Most Effective Methods for Holding and Retaining Slugs. Once a workpiece is physically setup in the machine, operators commonly check and verify the part alignment and flatness within the machine using a dial test indicator. Anyone who’s been paying attention to manufacturing technology over the last decade or so knows there are some big changes coming. Best Match; Time: ending soonest. Wire EDM machines do require a significant amount more maintenance and continuous TLC than other conventional machines such as lathes or mills. Machine … Wire EDM revolutionized this industry in how these tooling components were made, as prior to Wire EDM, many complex hardened tool steel components required very time consuming and difficult segmenting and grinding to be made. Control electronics can compensate to a certain extent, but the only real solution is to continually pump clean dielectric fluid through the cutting zone to flush it. “We’re even trying to figure out how to create a less-expensive wire EDM machine to be used specifically for separating additively built workpieces from their baseplates, so basically an electric bandsaw,” Langenhorst added. People have tried bandsaws, grinding, slitting wheels and all different kinds of things, and we’ve done quite well cutting the parts off the base plates using wire EDM. Many high-end machines are capable of achieving finer surface finishes down to 4µinRa (0.100µmRa) or finer and can produce accuracies at or below 1 micron (0.00004” or 0.001mm). As with any manufacturing technology, EDM faces certain hurdles that must be overcome to ensure that you’re getting the most from your machines. Registration on or use of this site constitutes acceptance of our This can include disassembly and cleaning of many components and re-calibration of the machine before being put back into production. But the experts agree that more customers are inquiring about ways to automate the process. Wire EDM has some built-in limitations and machine variables that make it challenging to automate, which is why robotic automation has never been a common trend with this technology. 1 shows schematically the basic working principle of EDM process. Normal electrode sizes can range from under 1.0” square to 6.0” square, but can be larger. WEDM Dielectric Basics P rior to plunging into the details of deionizing resin and regeneration, let’s first examine the role of the deionized water dielectric in a Wire EDM. “All EDM machining is performed unattended, so the direct labor rate and manufacturing cost are typically lower for EDM than other methods,” said Pfluger. As the dielectric fluid breaks down—whether as the result of age or contamination—the risk of unstable discharge increases. In traditional processes, metal workpieces are made from special grades of hardenable tool steels machined in an anneal of soft state to facilitate cutting. The Basics to Wire Erosion EDM (Electro Discharge Machining) Wire Erosion is a precision engineering process where a work piece is cut through with a strand of wire, it creates electrical sparks between the wire and the work piece, and these electrical sparks cut the work piece. “That doesn’t work too well: it’s way too brittle and the spark energy just shatters it like glass. (Image courtesy of Makino. While there are many specialized forms of electrical discharge machining, industrial EDM machines are commonly grouped into three categories: All three types operate on the same principal of erosion by electrical discharge discovered by Joseph Priestley in 1770, but their history, methods and applications are notably different. That’s where sinker EDM is a must.”, The principle advantages of EDM are that the process is very predictable, accurate and repeatable. “I’ve been asked to cut silicon wafer material, which is almost glass-like,” said Greg Langenhorst, Technical Marketing Manager at MC Machinery. The areas you can’t do with hard milling are sharp inside corners or very deep, thin ribs. EDM-WIRE Basic Training. For one, certain materials, such as high-nickel alloys—like those found in the aerospace industry—and carbide materials can present a greater challenge for EDM compared to standard tool steels. "We are seeing more and more EDM cells with specialized automation," said Raucci. However, if particle suspension is too high, these impurities will not separate from the fluid during filtration. In contrast, wire EDM machines normally use deionized water, into which only the sparking area is immersed. However, if you’re looking for a machining process that’s accurate, precise and stress-free—at least on the workpiece—EDM could be just what you need. Heterogenous materials, especially those with impurities, can also present a problem for EDM, as Langenhorst explained: “With carbon fiber composites, even though they are electrically conductive, the adhesives in them create some problems because they’re non-conductive. Wire EDMs require an NC G-code program for the shaped geometry. “The biggest thing with metal additive manufacturing is that you have to build on a base plate and then separate the part from that,” he said. What Characteristics Should Be Examined When Comparing Two Different EDM Wire Types? FAST4AXES is a seamlessly in CATIA V5 NC integrated software solution for offline programming and simulation of wire EDM processes, for 2 up to 4 axis wire EDM machines. Some of these are the same bottlenecks the arise for other machining processes, as Pfluger explained. NORTH AMERICAN EDM SUPPLIES 1-800-270-2627 www.edmsupplies.com Nothing on the machine is more irritating or disrupting than wire problems. Similarly, there’s typically more than one way to cut parts. “Over the years, sinkers have become less and less utilized because of high-speed hard milling. All newer machines operate fully submerged under a filtered water dielectric fluid, and high-pressure flushing is … The result is often a reduced need for post-processing or surface treatment. This “cheese cutter” approach to EDM works well, but it has an important limitation: the wire must pass entirely through the workpiece, making an essentially two-dimensional cut in a three-dimensional part. The NC programmer is supported with: Programming of 3D contours ; Support of geometrical features ; Machining operations for contouring, pocketing and point strategies “The goal is to ensure flawless, unattended machine operation over long hours, as this is where the process gains its productivity and lower manufacturing costs.”. Creating wire EDM features. Obviously, any workpiece that’s going to be machined with EDM has to be electrically conductive, but there’s more to the material limitations of electrical discharge machining than that. (Right) Top-Clamp Vise. 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