Surface Roughness Calculator — Formula
## Surface Roughness Parameters
Surface roughness describes the fine irregularities on a machined surface.
### Key Parameters
**Ra** (arithmetic average roughness) is the most common measure - the average deviation from the mean line.
**Rz** (ten-point height) is the average difference between the 5 highest peaks and 5 deepest valleys. Rz is typically 4-7 times Ra depending on the machining process.
### ISO Roughness Grades
N1 (Ra 0.025) through N12 (Ra 50), each step doubling the roughness.
Surface roughness describes the fine irregularities on a machined surface.
### Key Parameters
**Ra** (arithmetic average roughness) is the most common measure - the average deviation from the mean line.
**Rz** (ten-point height) is the average difference between the 5 highest peaks and 5 deepest valleys. Rz is typically 4-7 times Ra depending on the machining process.
### ISO Roughness Grades
N1 (Ra 0.025) through N12 (Ra 50), each step doubling the roughness.
Exemplo Resolvido
A machined surface with Ra = 1.6 micrometres.
- Rz = 1.6 x 5 = 8.0 micrometres
- Ra in micro-inches = 1.6 x 39.37 = 63 micro-in
- ISO grade: Ra 1.6 corresponds to N7