Manufacturing services · Chapter C · Method 17

Wire EDM

A thin charged wire cuts conductive metal by spark erosion, without cutting force. Produces sharp internal corners and very accurate profiles.

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Wire EDM machine with work tank and wire guides. Representative process photo · Ricard Polls · Public domain · Wikimedia Commons

How it works

Wire EDM, step by step.

A labelled schematic of the process (not to scale), and the four steps every job goes through.

Labelled diagram showing how wire edm works — Schematic · not to scale. Drawn by TCI Group.

STEP 01

Start hole

Drill a start hole, or start from an edge.

STEP 02

Thread wire

Thread brass wire through upper and lower guides.

STEP 03

Erode

Sparks remove metal in deionised water.

STEP 04

Skim passes

Further skim cuts refine size and finish.

Reference figures

What to expect.

Typical industry values to help you plan. We agree the figures for your part on the drawing.

AccuracyVery highMicron-level with skims

CornersSharp insideLimited by wire radius

ForceNoneNo distortion of thin parts

MaterialConductive onlyAny hardness

Materials	Hardened tool steel, carbide, stainless, titanium, copper and aluminium.
Finishes	Fine matte EDM finish; improved with extra skim passes.
Design guidance	Use where sharp internal corners or hard materials are needed. Through profiles only; it cannot make blind pockets. Allow for a start hole.
Best suited to	Punches, dies, extrusion dies, mould inserts and precision gears.
Watch-outs	Slow and costly for thick sections; conductive materials only.

Other methods in CNC machining

Previous: Drilling & tapping Next: Sinker EDM

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Reference figures are typical published industry values for planning, not a guarantee; final tolerances, materials and finishes are agreed in writing for each project.