pc study
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RSloop.
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December 3, 2002 at 12:29 pm #30937
I would like to ask 2 dobts. The first one is
Is it necessary to draw control charts for non capable process?
What should be the time interval between 2 pc studies in the same process/machine?
Please answer0December 3, 2002 at 1:31 pm #81198Ganesh,
1) No, one purpose of a control chart is to detect if a process is in control. You dont have to wait for a stable process to begin charting or even to calculate control limits.
2) Sampling frequency basically depends on how fast the process changes. There are mathematical methods, but it all comes down to sampling often enough to catch process changes while also sampling in an economic manner. You dont want to burden the operators or increase cost by sampling too frequently.
3) Make sure that you have a rational sample group with an adequate sample quantity. The quantity may be anywhere from 1 sample up, but it should be rational to the process and give you the sensitivity that you need to detect shifts in the process.
I hope that this helps a little.
Rick0 -
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