Electrical Discharge Machining

Electrical discharge machining erodes conductive material with controlled sparks, producing sharp internal corners, fine slots and precise shapes in hardened steels and other hard-to-cut metals.

Process overview

Electrical discharge machining removes material through controlled electrical discharges rather than conventional cutting forces. Wire EDM and sinker EDM can produce intricate geometries, narrow features and precision details in hardened or difficult-to-machine conductive materials. Projects may specify material, geometry, tolerance, surface finish, electrode requirements and inspection criteria.

Wire EDM cuts through the workpiece with a thin, continuously fed brass or coated wire that follows a programmed path — well suited to punches, dies, extrusion dies and precision profiles. Sinker (ram) EDM plunges a shaped graphite or copper electrode into the workpiece to create cavities, ribs and blind features, which is common in mold making. Small-hole EDM drills fine holes, for example start holes or cooling holes.

Because there is no cutting force, EDM can machine hardened material and delicate features without distortion. It is slower than milling, so it is typically chosen where conventional machining cannot produce the feature or would need several extra steps. The thin recast layer left by EDM may need to be limited or removed on fatigue-critical parts, depending on the application.

Typical capabilities & what manufacturers can produce

What manufacturers can produce

Punches, dies and stripper plates
Mold cavities, ribs and sharp internal corners
Extrusion dies and precision profiles
Narrow slots, keyways and gear profiles in hardened parts
Small holes and start holes

Capabilities under this process

Suitable materials

Materials commonly used with this process — an editorial reference, not a statement about facilities in the Metraxio network. Suitability always depends on the part and its application.

Tool Steel
Hardened die and mold steels.
Stainless Steel
Precision parts and hardened stainless components.
Titanium
Fine features without cutting forces.
Nickel Alloys
Superalloys that are difficult to cut conventionally.
Copper
Electrodes and conductive parts.
Graphite
Common electrode material for sinker EDM.

Relevant industries

Industries whose Metraxio industry guides list Electrical Discharge Machining as a common process, with the typical use in each.

Medical Devices
Fine features and hard materials.
Semiconductor
Fine features and hardened parts.
Packaging Machinery & Equipment
Cutting tools and dies.

What buyers should specify

The details that make Electrical Discharge Machining quotes comparable and let facilities be assessed on the right criteria.

Geometry: 2D profile (DXF) for wire EDM, 3D model for sinker work.
Material and hardness: EDM is often done after hardening, so state the final condition.
Tolerances and corner radii: Critical dimensions and the smallest acceptable internal radius.
Surface finish: Ra requirement — the number of finishing passes can be adjusted to it.
Electrodes: Whether the supplier should design and make the electrodes for sinker work.
Recast layer: Limits for fatigue-critical parts, if any.

On Metraxio these details become a structured manufacturing requirement. Processes, capabilities, materials, certifications and part size are checked against facility profiles; tolerances, finishes and inspection details travel with your drawings and are reviewed during quoting rather than used as automatic filters.

Frequently asked questions

Wire EDM or milling?

Milling is faster for most features. Wire EDM is chosen for through profiles in hardened material, sharp internal corners, very fine slots, or where cutting forces would distort the part.

Can EDM machine plastics or ceramics?

Conventional EDM needs an electrically conductive workpiece, so most plastics and ceramics cannot be machined this way.

Does EDM affect the surface?

EDM leaves a thin recast layer. For most parts this is acceptable, but fatigue-critical parts may need additional finishing.

Start a Manufacturing Project

Upload a drawing or describe what you need. Process context from this page can be reviewed before it becomes a structured requirement.