Hole EDM

Hole EDM (also called EDM drilling or fast-hole EDM) uses a thin, rotating tubular electrode with a flow of dielectric fluid through its center to erode small, deep holes in electrically conductive material with controlled sparks, rather than cutting mechanically.¹ It is commonly used for small-diameter, high-aspect-ratio holes in hardened materials, such as cooling holes in turbine components.

What drives hole EDM cycle time

Cycle time scales strongly with hole depth-to-diameter ratio and required straightness, since a very deep, narrow hole pushes the practical limits of electrode rigidity and dielectric flow, not unlike deflection risk in conventional drilling.

Where it appears on the drawing

Implied by a small-diameter, deep hole in a hardened conductive material, often with a tight straightness requirement that conventional drilling in that material cannot reliably achieve.

Common mistakes

Assuming hole EDM is simply 'EDM but for holes' with the same considerations as wire or sinker EDM; its practical limits are governed by electrode diameter, depth-to-diameter ratio and dielectric flushing, distinct concerns from either other EDM branch.

Why use hole EDM instead of drilling?

Because it can reach small, deep, precise holes in hardened conductive materials that a conventional twist drill would struggle to cut or would wear out quickly on.

What limits how deep a hole EDM hole can go?

Electrode rigidity and the ability to flush eroded material out through the dielectric fluid; very deep, narrow holes push both to their limits.

Is hole EDM the same as sinker or wire EDM?

No, it is a distinct branch using a rotating tubular electrode specifically for small, deep holes, rather than a formed cavity electrode or a profile-cutting wire.