The three commonly used surface roughness parameters and their values (Surface Roughness Parameters and their Values) are:
Profile arithmetic mean deviation (Ra)--arithmetical mean deviation of the profile;
Ten-point height of microscopic irregularities (Rz)--the point height of irregularities;
Profile maximum height (Ry)--maximum height of the profile.
Ra--the arithmetic mean of the absolute value of the profile deviation within the sampling length L.
Rz--The sum of the average value of the five largest profile peak heights and the average value of the five largest profile valley depths within the sampling length.
Ry - the distance between the top line of the profile peak and the bottom line of the profile valley within the sampling length L.
If the roughness is not marked on the drawing, Ra/Rz/Ry is selected as Ra by default. Comparison table of surface roughness (finish) between CHINA and the United States
Chinese old standard (finish finish) | CHINA's new standard (Roughness)Ra | American standard (micron)Ra | American standard (microinch) Ra |
▽ 4 | 6.3 | 8.00 | 320 |
6.30 | 250 | ||
▽ 5 | 3.2 | 5.00 | 200 |
4.00 | 160 | ||
3.20 | 125 | ||
▽ 6 | 1.6 | 2.50 | 100 |
2.00 | 80 | ||
1.60 | 63 | ||
▽ 7 | 0.8 | 1.25 | 50 |
1.00 | 40 | ||
0.80 | 32 | ||
▽ 8 | 0.4 | 0.63 | 25 |
0.50 | 20 | ||
0.40 | 16 |
