What Is Electrical Discharge Machining (EDM) and How Does It Work?
Taming electricity is one of humanity's most fruitful accomplishments. It illuminates cities, animates household appliances, and gives us an under-appreciated but irreplaceable fabrication tool.
What is Electrical Discharge Machining and Why is it So Valuable?
Sometimes, an exceptionally sturdy metal disagrees with engineers' attempts to alter its form. On these occasions, we pull a hidden trick from our sleeve: electrical discharge machining. EDM is a non-conventional machining modality that utilizes a unique form of action, electrical erosion. Discovered more than 300 years ago by one of chemistry's most influential historical dabblers, Joseph Priestley, EDM shapes workpieces with the curbed power of electricity.
How Does Electrical Discharge Machining Work?
The theory of electrical erosion is simple enough—we gradually remove material from a tough (but conducive) metal workpiece by zapping it with electricity.
And that's why EDM is called an unconventional machining process since it doesn't work through mechanical means. In fact, it doesn't even make physical contact with the piece it's shaping. Instead, the EDM machine discharges electrical energy from an electrode into the workpiece, which itself becomes the second electrode.
Each spark only removes a tiny amount of material. But this individually imperceptible subtractive method quickly becomes perceptible with frequency, as the EDM machine delivers 100,000 sparks per second.
To optimize and safeguard the zapping process, both the electrode and workpiece are submerged in dielectric fluid. Deionized water or hydrocarbon oils are excellent dielectric fluids and perform multiple duties. They wash away debris, cool things down, and act as insulators to avert abnormal electrical discharges.
How Does an EDM Machine Work?
The traditional form of EDM technology is known as sinker EDM and dates to the 1940s. As it electrically erodes material, it creates a plasma channel in the workpiece. The electrode then sinks into this channel to complete the shaping process, explaining the "sinker" in sinker EDM.
The second type of electrical machining, wire EDM, differs in the style of electrode used. As per its name, the electrode is a skinny strand of wire continually spooled through the machine. Electrical energy erodes the wire and the workpiece, so the wire is continuously renewed to provide the cleanest, most precise cut.
For small apertures, deep depressions, and other tricky forms that fall into the "hole" category, hole drilling EDM is a top choice. Engineers fit the machine with a tubular electrode through which the dielectric fluid flows. These specialized features allow unmatched size and depth for drilling purposes without necessitating post-treatment processes like deburring.
Electrify your output with Beltim!
With an extensive array of EDM equipment and decades of experience, Beltim achieves the tight tolerances and delicate small-scale accuracy needed to craft parts for the aerospace, automotive, medical industries, and many more. Contact us or get a free quote today to explore our capabilities and gain a competitive edge, electric or otherwise!