Atlas Copco ACTA 4000 - Page 118

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Figure 5 Individual measurements in groups, N=100 and n=5, X-bar control limits
N
x...xxx
X
N
++++
=
321
Equation 7 Centre Line
RAXUCL
2
X
+= RAXLCL
2
X
−=
Equation 8 Upper Control Limit for X-bars Equation 9 Lower Control Limit for the X-bar chart
The coefficient A2 is found in section 9.2.2.
0 2 4 6 8
10 12 14 16 18 20
70
71
72
73
74
75
76
77
78
79
80
UCL
X-bar
=76.19
Centre Line = 75.09
LCL
X-bar
=73.98
Index j
Measured value