Surface Roughness Chart
Surface Roughness Table - Shows the roughness average for different manufacturing processes in micrometers and microinches. The values are shown with a typical range and a less frequent range for each manufacturing process.
| |
Average Range |
| |
Less Frequent Range |
Manufacturing
Process |
Roughness Average
Top Number - Micrometers
Bottom Number - (Microinches)
|
| |
50 (2000) |
25 (1000) |
12.5 (500) |
6.3 (250) |
3.2 (125) |
1.6 (63) |
0.80 (32) |
0.40 (16) |
0.20 (8) |
0.10 (4) |
0.05 (2) |
0.025 (1) |
0.012 (.5) |
| Flame Cutting |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Snagging |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Sawing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Planing, Shaping |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Drilling |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Chemical Milling |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| EDM Elect Discharge Machining |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Milling |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Broaching |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Reaming |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Electron Beam |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Laser |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Electro-Chemical |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Boring, Turning |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Barrel Finishing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
50 (2000) |
25 (1000) |
12.5 (500) |
6.3 (250) |
3.2 (125) |
1.6 (63) |
0.80 (32) |
0.40 (16) |
0.20 (8) |
0.10 (4) |
0.05 (2) |
0.025 (1) |
0.012 (.5) |
| Electrolytic Grinding |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Roller Burnishing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Grinding |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Honing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Electro-Polish |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Polishing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Lapping |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Super Finishing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Sand Casting |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Hot Rolling |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Forging |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Permanent Mold Casting |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Investment Casting |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Extruding |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Cold Rolling, Drawing |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Die Casting |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
50 (2000) |
25 (1000) |
12.5 (500) |
6.3 (250) |
3.2 (125) |
1.6 (63) |
0.80 (32) |
0.40 (16) |
0.20 (8) |
0.10 (4) |
0.05 (2) |
0.025 (1) |
0.012 (.5) |
Ra = Roughness, average in micro-meters & micro-inches
| China's old standard (finish) |
China New standard (roughness) Ra |
American Standard(microns), Ra |
American Standard (Micro-inch), 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 |
| China Old Grade |
China New
Ra |
China New
Rz |
USA micron
Ra |
USA microinch
Ra |
| ▽ 1 |
50 |
200 |
|
|
| ▽ 2 |
25 |
100 |
|
|
| ▽ 3 |
12.5 |
50 |
|
|
| ▽ 4 |
6.3 |
25 |
8.00 |
320 |
| 6.30 |
250 |
| ▽ 5 |
3.2 |
12.5 |
5.00 |
200 |
| 4.00 |
160 |
| 3.20 |
125 |
| ▽ 6 |
1.6 |
6.3 |
2.50 |
100 |
| 2.00 |
80 |
| 1.60 |
63 |
| ▽ 7 |
0.8 |
6.3 |
1.25 |
50 |
| 1.00 |
40 |
| 0.80 |
32 |
| ▽ 8 |
0.4 |
3.2 |
0.63 |
25 |
| 0.50 |
20 |
| 0.40 |
16 |
| ▽ 9 |
0.2 |
1.6 |
0.20 |
12.5 |
| 10 |
| 8 |
| ▽ 10 |
0.1 |
0.8 |
0.10 |
|
| RMS (microinch) |
RMS
(µm) |
Ra (microinch) |
Ra
(µm) |
Grit Size |
80 58
47
34
17
14 |
2.03 1.47
1.2
0.6
0.43
0.36 |
71 52
42
30
15
12 |
1.32-1.90
0.46-0.64
0.3-0.4
0.18-0.38
≤0.15
≤0.08 |
80 120
150
180
240
320
400 |
Machining surface finish chart: Ra vs RMS
| USA Ra(µm) |
USA Ra (Micro inch) |
USA RMS (Micro inch) |
Machining Finish Method |
| 50.0 |
2000 |
2200 |
The most coarse machining or good rough casting surfaces |
| 25.0 |
1000 |
1100 |
Machining marks very obvious. Rough turning, boring, planning, drilling |
| 12.5 |
500 |
550 |
Machining marks obvious. Normal turning, boring, planning, drilling, grinding |
| 8.00 |
320 |
352 |
Machining marks visible. Normal turning, boring, planning, drilling , grinding |
| 6.30 |
250 |
275 |
Machining marks visible. Normal turning, boring, planning, drilling , grinding |
| 5.00 |
200 |
220 |
Machining marks not obvious. But still visible. Normal turning, boring, planning, drilling, grinding. |
| 4.00 |
160 |
176 |
Machining marks not obvious. But still visible. Normal turning, boring, planning, drilling, grinding. |
| 3.20 |
125 |
137.5 |
Machining marks not obvious. But still visible. Normal turning, boring, planning, drilling, grinding. |
| 2.50 |
100 |
110 |
Machining marks blur, but direction obvious. Number controlled turning, boring, planning, drilling, grinding. |
| 2.00 |
80 |
88 |
Machining marks blur, but direction obvious. Number controlled turning, boring, planning, drilling, grinding. |
| 1.60 |
63 |
69.3 |
Machining marks blur, but direction obvious. Number controlled turning, boring, planning, drilling, grinding. |
| 1.25 |
50 |
55 |
Machining marks direction blur, but still visible. Number controlled turning, boring, planing, drilling, grinding. |
| 1.00 |
40 |
44 |
Machining marks direction blur, but still visible. Number controlled turning, boring, planing, drilling, grinding. |
| 0.80 |
32 |
35.2 |
Machining marks direction blur, but still visible. Number controlled turning, boring, planing, drilling, grinding. |
| 0.63 |
25 |
27.5 |
Machining marks direction blur. Reaming, grinding, boring, rolling. |
| 0.50 |
20 |
22 |
Machining marks direction blur. Reaming, grinding, boring, rolling. |
| 0.40 |
16 |
17.6 |
Machining marks direction blur. Reaming, grinding, boring, rolling. |
| 0.20 |
12.5 |
13.75 |
Machining marks direction invisible. Grinding, super machining |
| 0.20 |
10 |
11 |
Machining marks direction invisible. Grinding, super machining |
| 0.20 |
8 |
8.8 |
Machining marks direction invisible. Grinding, super machining |
| 0.10 |
4 |
4.4 |
Surface dark gloss. Surper machining |
Ra is the arithmetic average of surface heights measured across a surface. Simply average the height across the microscopic peaks and valleys.
Ra and RMS are both representations of surface roughness, but each is calculated differently.
Ra is calculated as the Roughness Average of a surfaces measured microscopic peaks and valleys.
RMS is calculated as the Root Mean Square of a surfaces measured microscopic peaks and valleys. Each value uses the same individual height measurements of the surfaces peaks and valleys, but uses the measurements in a different formula.
Related References:
1. ISO 1302 DIN 4768 Comparison of Surface Roughness Values
2. Electrical Discharge Machining EDM Roughness Comparator
3. Polishing Polished Seamless Stainless Steel Pipe Tube
4. Stainless Steel Tubes Surface Roughness Review
5. Stainless Steel Bright Annealing/Annealed Tubes
6. China USA Surface Roughness Standard Comparison
7. Surface Roughness Conversion Chart of Stainless Steel Tube
8. Stainless Steel Tube Surface Finish Types
9. Cleaning of Stainless Steel Tubes
10. Post weld cleaning and finishing of stainless steels
11. Care and maintenance of stainless steel
12. British and American standards for tolerances, surface finish and testing of stainless steel
13. Surface Finish Degree Comparison Table between Rz Ra RMS
14. Surface Roughness Table
|
