Atlas Copco PowerMACS 4000 User Manual

SPC and Statistics
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7.2.4 SPC constants
The table below gives the constants to use in the mathematical formulas.
Sub-
group
size
Divisors for
estimate of
standard dev.
Factors for Control Limits
n
d2
c4
A2
D3
D4
A3
B3
B4
2
1.13
0.798
1.88
-
3.27
2.66
-
3.27
3
1.69
0.886
1.02
-
2.57
1.95
-
2.57
4
2.06
0.921
0.73
-
2.28
1.63
-
2.27
5
2.33
0.940
0.58
-
2.11
1.43
-
2.09
6
2.53
0.952
0.48
-
2.00
1.29
0.03
1.97
7
2.70
0.959
0.42
0.08
1.92
1.18
0.12
1.88
8
2.85
0.965
0.37
0.14
1.86
1.10
0.19
1.82
9
2.97
0.969
0.34
0.18
1.82
1.03
0.24
1.76
10
3.08
0.973
0.31
0.22
1.78
0.98
0.28
1.72
11
3.17
0.975
0.29
0.26
1.74
0.93
0.32
1.68
12
3.26
0.978
0.27
0.28
1.72
0.89
0.35
1.65
13
3.34
0.979
0.25
0.31
1.69
0.85
0.38
1.62
14
3.41
0.981
0.24
0.33
1.67
0.82
0.41
1.59
15
3.47
0.982
0.22
0.35
1.65
0.79
0.43
1.57
16
3.53
0.984
0.21
0.36
1.63
0.76
0.45
1.55
17
3.59
0.985
0.20
0.38
1.62
0.74
0.47
1.53
18
3.64
0.985
0.19
0.39
1.61
0.72
0.48
1.52
19
3.69
0.986
0.19
0.40
1.60
0.69
0.50
1.50
20
3.74
0.987
0.18
0.42
1.59
0.68
0.51
1.49
21
3.78
0.988
0.17
0.42
1.58
0.66
0.52
1.48
22
3.82
0.988
0.17
0.43
1.57
0.65
0.53
1.47
23
3.86
0.989
0.16
0.44
1.56
0.63
0.55
1.46
24
3.90
0.989
0.16
0.45
1.55
0.62
0.56
1.45
25
3.93
0.990
0.15
0.46
1.54
0.61
0.57
1.44

Atlas Copco PowerMACS 4000 Specifications

General

Brand	Atlas Copco
Model	PowerMACS 4000
Category	Power Tool
Language	English