N Grade
Overview
In Werk24, N Grades (Surface Roughness Grades) define the surface texture quality of a manufactured component. These grades indicate how smooth or rough a surface is, measured in Ra (Roughness Average, µm or µin).
As a software developer, understanding N Grades is essential for correctly processing and integrating surface finish requirements into CAD, CAM, and quality control systems.
What Are N Grades?
N Grades are internationally standardized surface roughness classifications that help manufacturers control the finish quality of machined parts. The grades range from N1 (super smooth) to N12 (very rough) and are defined by ISO 1302.
- Lower N numbers (N1 - N3) → Smoother surfaces (used in high-precision components like bearings).
- Higher N numbers (N8 - N12) → Rougher surfaces (used in castings or rough machining).
- N Grades are usually accompanied by Ra values, which specify the maximum allowable surface roughness in micrometers (µm).
N Grade Table
| N Grade | Roughness (Ra, µm) | Typical Application |
|---|---|---|
| N1 | 0.025 | Optical lenses, precision mirrors |
| N2 | 0.05 | High-precision instruments |
| N3 | 0.1 | Bearings, hydraulics |
| N4 | 0.2 | Precision machine components |
| N5 | 0.4 | Fine machining, aerospace |
| N6 | 0.8 | General engineering components |
| N7 | 1.6 | Standard machining |
| N8 | 3.2 | Castings, welds, general tolerances |
| N9 | 6.3 | Rough machining, sheet metal parts |
| N10 | 12.5 | Forged and rough milled parts |
| N11 | 25.0 | Unfinished castings |
| N12 | 50.0 | Very rough surfaces, raw materials |