January 2012 - Calibration/verification: a new survey?

A paper (1) on our Website has pointed out some problems linked to calibration/verification.

The first one is about the words themselves: calibration and verification have difficult-to-grasp differences in meaning, in English as well as in French. We recommend you read again this paper.

Another point we underlined is the "quality" of successive internal "calibrations" made by users themselves. This paper gives an example based on three UV-A radiometers from the same company.

Therefore, we are very happy to see that the NADCAP meeting, held October 2009 in Pittsburgh, showed that some people were concerned with this "calibration-chain".

"A request was made to the Aerospace Quality Systems (AQS) Task Group:

- Is it necessary to review calibration certificates to ensure accuracy and verify that all equipment was within calibration when equipment is calibrated by an internal calibration source? Both AC7004 and AS9100 require that records of the results of calibrations and verifications be maintained. There is no written requirement however, in the AQS system requiring review of those results."

In fact, this point is VERY SENSITIVE, and auditors have almost no means to be sure that the measuring equipment for which they are shown a "certificate of calibration" has been calibrated the right way.

This should be more and more often a cause for worry, as the auditor auditing, say, a PT line, shall only check that the documents meet the requirements. How is he or she able to question the ability of the "laboratory", of the "services company" which performed the calibration to do it properly? Many “internal calibration services” have neither the needed technical means nor the qualified personnel to do it.
Another point is the word "accuracy". Once again, it would be a good idea that auditing bodies, auditors, calibration laboratories all use the same words with the same meaning. Too many certificates for UV-A radiometers, for instance, come with the everlasting "accuracy: 5%" … which, for people accustomed to tolerances in calibration, has NO MEANING AT ALL. Auditors are too prone to look for these "magic words" on a certificate, just only because they have been told that this is the “proof” that the calibration is within expectations.

We would be glad to get comments, returns about this editorial.

Reference

(1) Patrick DUBOSC and Pierre CHEMIN, Quality of some calibration services, DPCNewsletter N°029, October 2010, on our Website:
http://www.ressuage-magnetoscopie-penetranttesting-magnetictesting-dpc.info/site/en/dpc-news/2010/152-dpcnews-029-qualite-de-certaines-prestations-detalonnage