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Charmilles EDM Finishes

Here is a chart of Charmilles EDM finish definitions for your convenience.

Charmilles EDM Finish Definitions
Charmilles Ra
Micro-meter
Ra
Micro-inch
Rrms
Micro-inch
-2 .08 3.14 3.9
-1 .09 3.54 4.4
0 .10 3.94 4.9
1 .11 4.33 5.4
2 .12 4.72 5.9
3 .14 5.51 6.9
4 .16 6.29 7.9
5 .18 7.09 8.9
6 .20 7.87 9.9
7 .22 8.66 10.8
8 .25 9.84 12.3
9 .28 11.02 13.8
10 .32 12.60 15.8
11 .35 13.78 17.2
12 .40 15.60 19.5
13 .45 17.60 22.0
14 .50 19.60 24.5
15 .56 21.60 27.0
16 .64 25.00 31.3
17 .72 28.10 35.2
18 .80 31.20 39.0
19 .91 35.50 44.4
20 1.01 39.40 49.3
21 1.12 43.70 54.6
22 1.28 49.90 62.4
23 1.44 56.20 70.3
24 1.60 62.40 78.0
25 1.81 70.60 88.2
26 2.03 79.10 98.9
27 2.24 87.40 109.2
28 2.54 99.10 123.9
29 2.84 110.80 138.5
30 3.15 122.90 153.7
31 3.60 140.40 175.5
32 4.05 158.00 197.5
33 4.50 175.50 218.8
34 5.10 198.90 248.6
35 5.70 222.30 277.9
36 6.30 245.70 306.2
37 7.20 280.80 351.0