Surface Finish Converter
Convert roughness between Ra, Rz, RMS and other parameters to align inspection readings with drawing notes. Remember: cross‑family conversions are approximate.
Units:
Typical Surface Finish by Process
Values are Ra (arithmetical average roughness). Actual results vary with tooling, parameters, and materials.
| Process | Typical Ra (µm) | Typical Ra (µin) |
|---|---|---|
| Milling | 0.8 – 6.3 | 32 – 250 |
| Turning | 0.4 – 6.3 | 16 – 250 |
| Drilling | 1.6 – 6.3 | 63 – 250 |
| Reaming | 0.8 – 3.2 | 32 – 125 |
| Boring | 0.4 – 6.3 | 16 – 250 |
| Grinding | 0.1 – 1.6 | 4 – 63 |
| Honing | 0.1 – 0.8 | 4 – 32 |
| Lapping | 0.05 – 0.4 | 2 – 16 |
| Broaching | 0.8 – 3.2 | 32 – 125 |
| Sawing | 1.6 – 25 | 63 – 1000 |
| EDM (wire/sinker) | 0.25 – 2.8 | 10 – 112 |
| Polishing | 0.05 – 0.4 | 2 – 16 |
| Shot blasting | 1 – 6.3 | 40 – 250 |
| Sand casting (as-cast) | 6 – 12 | 240 – 480 |
| Investment casting (as-cast) | 0.8 – 3.2 | 32 – 125 |