Tech Focus Complex, fast and fully automated: The art of wire erosion
Wire erosion is a very versatile method. As long as a material is conductive, it can be machined with EDM. The downside of the process, like its speed, are compensated by its accuracy, low running costs and minimal requirements for human intervention.
The UK manufacturing industry is under more pressure than ever to meet demanding sales targets, streamline operations and increase productivity to compete in the global marketplace. To do this successfully, manufacturers need to be sure their machines and tools are up to the task.
While traditional machine methods such as milling, lathing and grinding remain popular for certain processes, wire EDM, or Electronic Discharge Machining, has built a reputation as a more precise, efficient and cost-effective machining method. Initially used in the 1960s as a means of making tools from hardened steel, wire EDM has since developed into a highly reliable and accurate process for the manufacture of complex and durable components.
Andrew Spence, Robocut Product Manager at Fanuc UK, says: “The principle of wire EDM is a spark that is generated between the workpiece and the electrode, similar to the spark that you see in films when the main character hotwires a car. With EDM, you control this spark, which melts the material and creates the shape you need.”
“Wire EDM involves a thin piece of wire, which is pulled between two guides to act like a high-precision bandsaw. Pre-determined computer numerical controlled (CNC) drive systems guide the wire into making complex shapes.”
The CNC aspect of the machine allows manufacturers to specify the shape and boundaries of the cut with minute precision. As Andrew explains, this helps them to produce the same result every time.
“EDM is accurate down to +/- 3 µ on tolerance and +/- 1.5 µ on positioning,” he says. “You can only achieve that with milling if the shape is relatively simple. With an EDM process, once you’ve proven the first one, the repeatability is the same for each one.”
The accuracy of wire EDM, guided by the CNC drive systems, has led to the introduction of such machines across a variety of sectors.
Andrew says: “EDM has been a very big part of the manufacturing process for toolmakers, but you can now also see wire EDM in motorsport, aerospace, university R&D and general engineering. Medical is also a major sector for wire EDM, which is used to manufacture medical devices such as stents or implants. This is because EDM doesn’t use a cutting force like traditional machines, so you can cut very thin and accurate components.”
“Wire EDM can also cut a different form for the top and bottom of a piece of material, which allows you to create extrusion dies for door seals on cars, for example.”