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Copper EDM Electrodes
An EDM electrode is a machined copper part with one extra rule: whoever machines it has to know whether the spark gap is already in the model. Electrodes are scrapped more often over that one question than over any tolerance.
We match electrode work with shops that cut copper regularly and ask about the gap before they quote.
What the part needs
- Grade
- C10100 oxygen free is the standard for burn consistency. C14500 is used when electrode geometry is complex and machining time dominates.
- Gap offset
- Stated on the drawing: dimensions are nominal cavity size, or already offset for the gap.
- Working face finish
- Per the burn you are running. Finishing electrodes need a finer face than roughing ones.
- Shank and location
- Holder system named so the shank is machined to fit it.
- Quantity
- Roughing and finishing electrodes, and how many of each. Electrodes wear.
- Detail
- Internal corner radii as generous as the cavity allows. A sharp electrode corner is a small cutter and a slow feed.
Grades that fit
Published typical values for the alloy, never a promise from a shop. Each grade has its own reference page.
- C10100
Oxygen free electronic copperStructural uniformity gives consistent discharge across the face. The default electrode copper. - C11000
Electrolytic tough pitch copperWhere burn consistency is less demanding and cost matters more. - C14500
Tellurium copperWhen the electrode is complicated enough that machining time dominates. Ask the EDM shop before choosing it for them.
What drives the price
If a quote looks high, one of these is usually the reason, and most of them can be changed on the drawing.
- DetailFine ribs, sharp corners and deep slots are exactly the geometry copper machines slowest.
- Working face finishA mirror finish electrode is a finishing operation on top of the machining.
- Electrode countA cavity usually needs more than one electrode. Order the set, not one.
- Gap mistakesAn electrode cut to the wrong offset is scrap. Write the offset on the drawing.
What to put on the drawing
Send these and the quotes you receive will be comparable. The RFQ builder writes the material lines for you.
- Electrode grade, or the workpiece material and finish so a shop can advise
- Whether the gap offset is already applied, and how much
- Finish on working faces only
- Holder or shank standard
- Roughing and finishing split, and quantities of each
- Whether repeat sets will be ordered
Send the drawing
Short version here, or the full RFQ form with tolerance, finish and plating fields. Your files go only to the shops we match. Ask for an NDA and nothing moves until it is signed.
We are a matching service, not a machine shop. How matching works.
Questions buyers ask
Something else? Email .
Copper or graphite for my electrode?
Copper for fine detail, better finish and carbide workpieces. Graphite for complex shapes where machining time dominates and the finish requirement is ordinary. The total time to make the electrode usually decides it.
Which copper grade should the electrode be?
C10100 oxygen free by default, for burn consistency. C14500 tellurium copper when the electrode is complex and machining time is the cost, accepting a small trade in burn behaviour.
Do I need to apply the spark gap myself?
Either is fine, but the drawing must say which. Most scrapped electrodes are the result of that line being missing.
Can I get copper tungsten electrodes?
For fine detail, deep ribs and low wear, yes. It is a specialist material, more expensive and harder to machine. Say so in the RFQ and we match accordingly.