EN
DE
Surface Roughness Chart
Achieve the perfect finish for every part — from precision-machined surfaces to ultra-mirror optical polish.
Our advanced CNC machining, grinding, and mold-polishing capabilities deliver consistent surface roughness from Ra 12.5 µm down to Ra 0.01 µm (SPI A1).
Whatever your application — cosmetic, functional, or high-performance — we ensure a finish that enhances durability, appearance, and product value.
Surface Roughness Table |
||||
Roughness Value (Ra, µm) |
Symbol (ISO N Grade) |
Microinch (µin) |
Typical Process |
Surface Appearance |
| 50–100 µm | N12–N11 | 2000–4000 | Heavy milling, rough turning | Very rough with deep tool marks |
| 25–50 µm | N10 | 1000–2000 | Rough machining | Clearly visible machining marks |
| 12.5–25 µm | N9 | 500–1000 | Semi-rough milling | Noticeable texture |
| 6.3–12.5 µm | N8 | 250–500 | Semi-finish machining | Visible tool marks |
| 3.2–6.3 µm | N7 | 125–250 | Precision machining | Smooth but slight tool marks |
| 1.6–3.2 µm | N6 | 63–125 | High-precision machining | Smooth surface |
| 0.8–1.6 µm | N5 | 32–63 | Fine grinding, precision CNC | High smoothness |
| 0.4–0.8 µm | N4 | 16–32 | Superfinishing, honing | Very fine, satin texture |
| 0.2–0.4 µm | N3 | 8–16 | Polishing | Shiny, near mirror |
| 0.1–0.2 µm | N2 | 4–8 | Fine polishing | Highly glossy |
| 0.05–0.1 µm | N1 | 2–4 | Mirror polishing (equivalent to SPI-A2) | High mirror clarity |
| < 0.05 µm | — | <2 | Ultra-mirror (SPI-A1) | Optical-grade mirror |
Get In Touch
Our senior sales and technical engineers will answer you questions fast and efficient.