CNC vs Wire EDM: which process is right for your part.
CNC machining and wire EDM do not compete: they solve different problems. CNC cuts 3D geometry fast; wire EDM reaches where the tool cannot, in material milling will not survive. Here is the difference, in one table and with no spin.
CNC milling and wire EDM, side by side.
| Factor | CNC milling | Wire EDM (0.13 mm) |
|---|---|---|
| Typical tolerance | ±0.01 to ±0.025 mm | ±0.005 to ±0.010 mm |
| Material hardness ceiling | Up to ~HRC 50 with cutting tools | HRC 65 and beyond, with no loss of hardness |
| Sharp internal corner (min. radius) | ~R0.4 mm, limited by tool diameter | R0.065 mm with 0.13 mm wire |
| Surface finish | Ra 0.4 to 1.6 µm depending on operation | Ra 0.4 to 0.8 µm, no secondary polishing |
| Contact with the part | Yes, there is cutting force | No, zero mechanical stress on the part |
| Best for | Complex 3D geometry and volume | 2D profiles, hardened steel, tight corners |
| Speed | Faster on complex 3D parts | Faster on profiles in hard material |
Milling solves it, and solves it fast.
- The part has three-dimensional geometry: faces, holes, pockets and surfaces across several planes.
- The material stays under HRC 50 and internal radii are larger than 1 mm.
- You need a repeatable production run, not a single piece.
- Lead time is critical and milling solves the part without risk.
The tool will not fit, or the material will not forgive.
- An internal corner has to be almost sharp: a radius no round tool can leave.
- The material is hardened above HRC 50 and you cannot risk distortion.
- The part is thin or fragile and will not take cutting force.
- The profile is through-cut and the finish has to come out fine with no secondary operation.
On most parts, you do not have to choose.
The question is not always CNC or EDM. Many parts need both: rough soft in CNC, heat treat, then finish the critical detail by wire EDM. The problem shows up when each process lives in a different shop: the part loses its measuring references every time it changes plants, and the tolerances stack up.
At RIC both processes sit under one roof, with the 2026 Saturno wire EDM (0.13 mm wire) next to the CNC centers. The part keeps the same references from bar stock to shipment, on a single purchase order. So before we quote, we review your drawing and tell you which process each feature needs. If milling reaches it, we mill it. If a corner needs EDM, we move it to EDM. No overselling.
What buyers ask before they decide.
Which is more precise, CNC or wire EDM?
Wire EDM. It reaches ±0.005 mm with no force on the part, against the ±0.01 mm typical of CNC milling. For very tight tolerances in hardened material, wire EDM is the correct technical choice.
Does wire EDM work on any material?
Only on electrically conductive materials: steels, special alloys, carbide. It does not cut plastics, ceramics or other non-conductive materials. For those, CNC machining is the right process.
Why can CNC not make sharp internal corners?
Because the cutting tool is round and leaves an internal radius equal to its own radius. A 1 mm end mill leaves at least a 0.5 mm radius. The 0.13 mm wire in EDM leaves an internal radius close to 0.065 mm.
Which process is cheaper?
For parts that milling can solve, with radii over 1 mm and material under HRC 50, CNC is usually faster and more economical. Wire EDM is justified when CNC cannot reach the geometry or would put the part at risk.
Can I combine both processes in one part?
Yes, and often that is the right call. We rough in CNC, apply heat treatment and finish the critical detail by EDM. It all happens in one plant, keeping the same measuring references from bar stock to final inspection.
How do I know which one my part needs?
Send us the drawing. If milling solves it, we tell you; if it needs wire EDM, we tell you that too. We do not sell you a process that does not solve your part.
Not sure which one your part needs? We are.
Send us the drawing or CAD file. We tell you which process solves each feature and quote within 24 business hours.