Everything You Need to Know About EDM?

Electrical Discharge Machining, EDM, Beltim & Associates

When a material is too tough to cut using physical tools, who are you gonna call? Electrical Discharge Machining! EDM is a machining method that works through electrical erosion, a process detailed by scientist extraordinaire Joseph Priestly in 1770. Nearly two centuries later, in the 1940s, two teams (one American, one Russian) simultaneously developed the sparking technologies that birthed today’s various industrial EDM disciplines. 

How Does EDM Work?

EDM shapes workpieces through electrical erosion, using electro-thermal energy to gradually remove material from a hunk of conductive metal. This electro-thermal energy is delivered in the form of sparks. Each spark only removes a tiny bit of material, but an EDM machine worth its salt can deliver 100,000 of them every second. 

All this is made possible by the electrical potential between two electrodes. The first electrode is part of the electric discharge machine: a small point, rod, or wire generally composed of copper, graphite, brass, or a tungsten alloy. The second electrode is the workpiece itself, which must be electrically conducive. As such, EDM has become an invaluable tool when dealing with exotic metals or those that resist other machining methods. Commonly worked metals include aluminum, various steel variants, cobalt, titanium, and many more. 

To facilitate fabrication, both electrodes must be submerged in dielectric fluid. This fluid is often deionized water or a hydrocarbon oil, and it helps reduce unwanted sparking while offering thermal control. The flowing dielectric fluid also washes away debris, as the EDM machine’s electrode and the workpiece are eroded by rapid-spark electrical action. 

What Makes EDM So Irreplaceable?

EDM is an exceptionally reliable process that provides excellent precision, reproducibility, and minimizes error rates. The finished pieces also profit from electrical erosion because, vitally, there’s no physical contact between the machine and the workpiece since a space, or spark gap, separates the two.

It’s a great advantage: the lack of contact means that no physical stress is added to the equation. Eliminating the traditional stresses and tooling wear that are unavoidable through other machining modes spares the workpiece from distortion or warping. 

It also offers better quality, longer-lasting end-product parts that may not require further finishing. The resultant time, labor, and cost savings are passed on to both the manufacturers and the clients. In addition, the exceptionally polished finishes made possible through EDM make it a go-to process for producing precision dies and molds. 

What Are The Two Main Types of Electrical Discharge Machining?

Multiple EDM disciplines have been developed since its inception around 80 years ago, though the primary two types are wire EDM and sinker EDM. True to its name, wire EDM utilizes a wire as an electrode. The wire is constantly spooled through the machine since electrical erosion whittles the wire as well as the workpiece. Continually refreshing the wire yields the cleanest, most accurate electrical cuts. This EDM variant is generally used to cut all the way through a workpiece.

Another ubiquitously used format is sinker EDM, considered the conventional EDM process and named “sinker” because the electrode sinks into the workpiece as the desired cut is made. 

Sinker EDM excels at achieving apertures, holes, odd angles, and tiny features like no other fabrication process, making it indispensable for crafting highly accurate parts with complex interior geometries. Its exceptional accuracy lends well to creating components for the aerospace, defense, medical, dental, automotive, and energy sectors. 

Electrical discharge machining has revolutionized modern production. Its precision and reliability have improved every field, including medicine, travel, energy production, and aerospace. 

Beltim & Associates works with all industries to provide the parts and processes that make modern advances possible. And you can add a little lightning to your next project by contacting us today or getting a free quote!

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