Quality Magazine

Other Dimensions: Changing the Rules

December 2, 2010
Cal labs provide a bunch of numbers. What is done with those numbers is up to the customer.

Most of the world seems to function quite well using ISO 17025 as a standard for calibration laboratories. Unfortunately, some people are not content with this and have to get their fingerprints all over it with interpretations or special requirements to get it to suit their industry. The fact that similar industries around the world don’t feel the need to do so just doesn’t seem to register.

To make matters worse, the basic functions of a calibration laboratory don’t seem to be understood by many who want to download processes and conditions on them. Often these additional requirements are attempts to make up for lack of knowledge by users of the reports.

For the record, I should explain my understanding of what a calibration laboratory is all about-without getting too technical, of course. Basically, it is a place where you send your stuff to get calibrated and they issue a report with their measurements and a qualifier as to how good they think those measurements are-the uncertainty statement.

That’s it. Their service provides you with a whole bunch of numbers. Sorry about that technical term there. What is done with those numbers is up to the customer. Now, if you want some sort of analysis, quality processes done with the data or reverse engineering, most labs will be pleased to accommodate you for an additional fee.

But all too often, everyone expects this additional service to be included in the calibration cost. It is not uncommon for the $50 calibration job to consume $200 worth of consulting, teaching, training, analyzing, reviewing and making decisions the customer alone should be making.

On a less dramatic scale, many requests that cal labs deal with are of little value to anyone so they can be just as problematic. In some cases these gems are written into a version of ISO 17025 or are requested because an auditor says they should be on a report. Here are some examples:

Traceability numbers. Usually they want to see a NIST number, which on its own means nothing and may not directly relate to anything in the lab issuing the report. Word on the street is that NIST is becoming increasingly fed up with its numbers decorating reports, often implying something that doesn’t exist. A properly accredited ISO 17025 lab cannot be accredited without the actual documents being checked. The standard makes it clear that reports do not have to show these numbers.

Compliance statements. The lab is asked to state whether the item calibrated meets certain criteria, some of which may be values from the customer rather than a published standard. If the lab has provided the data and the customer knows the criteria, why is the lab’s opinion required?

Acceptance criteria. Labs are frequently asked to provide acceptance criteria when that information is more reliably provided by the customer who knows how the equipment will be used. Too often numbers are lifted from published standards whose numbers are for new, not used, items.

Re-cal dates. This type of information may be requested so the report reader can see when the equipment used to do the calibration is due for calibration. I’m not sure what benefit will be derived from this information without knowing a lot more about the equipment and conditions of use.

Other requests in this regard relate to having the report show when the item that has been calibrated should be calibrated again. Because the standard forbids labs from doing so unless the customer has advised the frequency, the whole process seems redundant.

Equipment used. To comply with this request, the lab is supposed to list the principal equipment used for the calibration. The brevity of such listings often makes them useless. For example, for thread gage pitch diameter it might show “bench mike and wires.” I don’t know about you, but such a listing would not prove to me that they had the right hardware.

Massaging the data from the calibration report to make decisions has some of my colleagues concerned. Why? It looks like the customer is downloading decision-making to the lab to avoid responsibility. When the wheels fall off, all fingers will point to the lab that said the gage was “good.”

As can be expected, only the lawyers will win.