Free Surface Roughness Calculator
Convert between surface roughness parameters Ra and Rz using an approximate relationship.
Ten-Point Roughness (Rz)
8.00 micrometres
Ten-Point Roughness (Rz) vs Arithmetic Mean Roughness (Ra)
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.
Example Calculation
A machined surface with Ra = 1.6 micrometres.
- 01Rz = 1.6 x 5 = 8.0 micrometres
- 02Ra in micro-inches = 1.6 x 39.37 = 63 micro-in
- 03ISO grade: Ra 1.6 corresponds to N7
Frequently Asked Questions
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