ACTA 4000 User Guide Printouts from ACTA
9836 4171 01 2008-12 119 (136)
Figure 6 X-bar control chart
If X-bars fall outside the control limits, the process should be investigated further.
For further information, please contact your local Atlas Copco representative.
Individual observations outside the control interval may not indicate a problem.
Do not mistake control interval for tolerance.
The tolerance limits are based on the feasibility of the manufactured part, while the control limits are
based on the inevitable randomness scattering data. The control limits need to be tighter than the tolerance
limits.
Index j
0 2 4 6 8 10 12 14 16 18 20
70
71
72
73
74
75
76
77
78
79
80
X-bar
UCL
X-bar
=76.19
Centre Line =75.09
LCL
X-bar
=73.98
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