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)
सूत्र
## 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.
हल किया गया उदाहरण
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
अक्सर पूछे जाने वाले प्रश्न
What Ra values do common processes achieve?
Grinding: 0.1-1.6 Ra. Turning: 0.8-6.3 Ra. Milling: 0.8-6.3 Ra. Lapping: 0.012-0.1 Ra. Polishing: 0.006-0.05 Ra. Sand casting: 12-25 Ra.
Why specify surface roughness?
Roughness affects friction, wear, fatigue life, sealing ability, appearance, and coating adhesion. Tighter roughness requirements increase machining cost and time, so specify only what the function requires.
How is surface roughness measured?
The most common method uses a stylus profilometer that drags a diamond tip across the surface and records height variations. Non-contact methods include optical interferometry and confocal microscopy.
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