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The stability of our instrument is monitored by SPC chart. The shift of the instrument will be detected by both control limit and so-called “shutdown SPEC.”.
For the small shift, we control it by the control limit, which is calculated by 3-sigma. We do not shutdown the instrument if its shift is only out of control limit. We just give a warning.
But for the large shift, we gate it by so-called “shutdown SPEC.”; and the gauge will be shutdown whenever its shift is out of “shutdown SPEC”. The “shutdown SPEC ” is defined as one-tenth of product SPEC. (For example, the product SPEC is 4000 ang +/-400 ang, then we will give the gauge shutdown SPEC to be 4000ang +/40ang)
Here are my questions:
(1) If you, too, monitor the stability of your instrument by SPC chart, when do you shutdown the instrument? Out of control limit or SPEC.?
(2) If you shutdown the instrument when out of SPEC,, how do you define the SPEC.?
Your comments are welcom.
Best regards
For the small shift, we control it by the control limit, which is calculated by 3-sigma. We do not shutdown the instrument if its shift is only out of control limit. We just give a warning.
But for the large shift, we gate it by so-called “shutdown SPEC.”; and the gauge will be shutdown whenever its shift is out of “shutdown SPEC”. The “shutdown SPEC ” is defined as one-tenth of product SPEC. (For example, the product SPEC is 4000 ang +/-400 ang, then we will give the gauge shutdown SPEC to be 4000ang +/40ang)
Here are my questions:
(1) If you, too, monitor the stability of your instrument by SPC chart, when do you shutdown the instrument? Out of control limit or SPEC.?
(2) If you shutdown the instrument when out of SPEC,, how do you define the SPEC.?
Your comments are welcom.
Best regards