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What is Electrical Discharge Machining?

Advanced, precise machining methods to manufacture America’s future.

What is it?

Electrical Discharge Machining, commonly called EDM, is a precision manufacturing process used to cut, shape, or drill electrically conductive materials using controlled electrical sparks. Unlike traditional machining methods, EDM does not rely on physical contact between a cutting tool and the workpiece. Instead, material is removed through rapid electrical discharges that vaporize tiny amounts of metal with extreme accuracy.

The resulting product, is an exact, smooth, inverse replica of the electrode.

EDM excels where conventional machining struggles, especially with hard materials, complex geometries, and delicate features that would be difficult or impossible to produce with mills or lathes.

How does it work?

At its core, EDM works by creating a series of controlled electrical sparks between two conductive components:

  • The electrode (tool) — most often made from graphite or copper
  • The workpiece — the material being machined

Both are submerged in a dielectric fluid (typically deionized water or oil), which plays a critical role in the process.

The Basic Process

  1. A small voltage is applied between the electrode and the workpiece
  2. As the gap closes, the electric field becomes strong enough to create a spark
  3. The spark generates intense localized heat (thousands of degrees)
  4. A microscopic amount of material melts and vaporizes
  5. The dielectric fluid flushes away the debris
  6. The process repeats thousands of times per second
Placeholder image. Need diagram here

Because the electrode never physically touches the workpiece, there are no cutting forces, no tool chatter, and almost no mechanical stress on the part.

Common types of EDM

Ram (Sinker) EDM

Ram EDM uses a machined electrode that is “sunk” into the workpiece. The cavity created mirrors the shape of the electrode.

Best for:

  • Mold and die cavities
  • Sharp internal corners
  • Complex 3D shapes
Wire EDM

Wire EDM uses a continuously fed thin wire as the electrode, allowing it to cut intricate profiles through thick material.

Best for:

  • Precision contours
  • Tight tolerances
  • Bandsaw-like cutting

Read more about our types of Ram EDMs

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What Materials Can EDM Machine?

EDM works on any electrically conductive material, regardless of hardness:

  • Tool steel
  • Hardened steel
  • Stainless steel
  • Titanium
  • Carbide
  • Aluminum
  • Exotic alloys (Inconel, Hastelloy, etc.)

Material hardness has little effect on EDM performance—a major advantage over traditional machining.

How ArcForge Brings EDM to the Workshop

Until now, EDM machines have been expensive, complex, and out of reach for individuals and small shops. We’re here to bring the benefits of EDM technology to everyone.

Modern electronics, open knowledge, and DIY-friendly designs make it possible to build compact, affordable EDM systems capable of real, useful work.