Wire EDM & Sinker EDM — design guidelines
Wire EDM erodes material with a spark, so hardness is irrelevant and cutting forces are essentially zero. What matters instead is that the material conducts electricity, that the wire can be threaded, and that the profile is a constant cross-section.
Constraints specific to this process
These are the limits that come from this process in particular. The general rules on wall thickness, corner radii and hole depth apply on top of them.
| Parameter | Design to thisNo surcharge, no discussion needed | We can reachAchievable, but affects price or lead time | Where the limit comes from |
|---|---|---|---|
| Internal corner radius | 0.15 mm | 0.08 mm | The minimum radius is the wire radius plus the spark gap. With 0.25 mm wire that is about 0.15 mm; a 0.1 mm wire reaches 0.08 mm but cuts far more slowly. |
| Start hole for closed profiles | Ø 2 mm, we drill it | Ø 0.5 mm | The wire has to pass through the part before an internal profile can be cut. If you do not show a start hole we put one in the scrap area — tell us if its position matters. |
| Workpiece thickness | ≤ 150 mm | ≤ 300 mm | Cutting time scales with thickness. Beyond 150 mm flushing gets difficult and we need more skim passes to hold the profile straight through the full height. |
| Achievable tolerance | ±0.01 mm | ±0.003 mm | With no cutting force there is no deflection, so accuracy comes down to how many skim passes we run. ±0.003 mm needs four passes and about three times the cutting time. |
What we see go wrong most often
Recurring issues on the drawings that reach us. None of them are hard to avoid once you know to look for them.
- Sending an aluminium or titanium part with a varying cross-section. Wire EDM only produces constant-section profiles (or tapers) — a shape that changes along the wire axis needs milling.
- Specifying wire EDM for a non-conductive material. Ceramics, plastics and composites cannot be spark-eroded at all.
General machining rules
The numbers that apply across every cutting process — wall thickness, radii, holes, threads, tolerances and cost drivers.
- Wall thickness
- Internal corner radii
- Holes and threads
- Pockets, cavities and undercuts
- Tolerances, text and surface callouts
- What actually drives the price
Every quotation includes a manufacturability review against these rules. If something in your model falls outside them, we tell you before you commit, not after the first article fails.
Not sure whether your part clears these limits?
Send the STEP file. A manufacturing engineer marks up anything that will be difficult and returns it with the quotation — no charge, no obligation.