Engineering
Surface Finish Converter & Selector
Convert a surface roughness between µm and µin, see which operations actually reach it, and get a target when you are starting from what the surface has to do.
Result
Ra 1.600 µm
63.0 µin. 6 operations in this list has a typical band that includes it.
Reaches it
- Turning Ra 1.6–6.3 µm
A normal turning pass. The feed rate sets the finish more than the speed does - halving the feed roughly halves the Ra.
- Milling Ra 1.6–6.3 µm
A normal milling pass. A right-angle face is usually worse than a profile, because of the tool marks crossing the surface.
- Fine turning / finish milling Ra 0.8–1.6 µm
A finishing pass with a sharp tool, a light feed and a rigid setup. Reached on the faces that were aimed at, not across the whole part.
- Die-sinking EDM Ra 0.4–3.2 µm
Leaves a recast layer. The finish is set by the electrode and the spark settings, and a finer finish takes disproportionately longer.
- Wire EDM Ra 0.4–1.6 µm
Through-profiles and fine sharp corners. Multiple skim passes each refine the finish and each add a full pass around the profile.
- Bead blasting Ra 0.8–3.2 µm
A texture, not a refinement: it hides tool marks instead of removing them, and it usually raises the Ra compared with what went in.
What this means for the part
- A seal has to be compressed against the surface without a scratch for the fluid to follow. Ra is only half of it: the surface also has to be free of gouges, and Rz is the parameter that shows those.
Typical bands for sealing face (o-ring, gasket, hydraulic)
- Fine turning / finish milling Ra 0.8–1.6 µm
- Precision milling / turning Ra 0.4–0.8 µm
- Surface grinding Ra 0.2–0.8 µm
Every operation in the list
Unit conversion is exact; the achievable ranges are typical process bands from machining practice, not a guarantee for your part, machine or setup. Confirm the finish against the drawing before relying on it.
What you provide
- Roughness value
- Unit
- Parameter (Ra / Rz / Rq)
- What the surface has to do
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