Validity of previous inspections when equipment is found out of calibration


elva noriega

I was reviewing point 4.11.2.f and I would like any comment about what steps can be indicated in our working instructions in order to meet it, maybe we need to indicate that we will any kind statistical analysis, but then... what kind ?..

Dan Larsen

Gotta be QS...what to do when a gage is found out of calibration.

This requirement is effectively a risk assessment. The out of calibration condition means that all measurements you've made since the last calibration are suspect and may contain error.

Generally, I suggest an analysis that consists of defining the error, determine how much the error affects you're measurements within the tolerances that you apply, then statistically sample inspection results from production during the period to demonstrate (hopefully) that the process was operating at or near the mean and that the error would have no significance on parts that were produced. Then I suggest a review of previous calibration information to determine if a revision to the calibration frequency is required.

If the analysis suggests that nonconforming product has been shipped, then you have a potential recall issue and the system should require notification of the customer.

I think this single clause is the biggest driver to have companies critically evaluate their calibration frequencies and ensure that their gaging systems have capability well within the tolerances that they measure.

As for handling it in a system, I suggest it be included at the procedural level with responsibility assigned to invoke a corrective action in the event an out of calibration condition is reported. Try to use the systems you already have in place instead of designing a new one.
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