Changing calibration frequency

[Ninja]

FWIW, I extended the calibration of our etched glass calibration grid (used to verify/calibrate a CMM) to 10yrs...the only way to change the thing was to break the glass or scratch it so bad it wouldn't work anyway.
Even after 10yrs, we had the CMM calibrated by an outside source then used that etched glass to re-verify and it came out clean...and then used that data to justify calling the glass "recalibrated" for another 10yrs.
As long as you have a justified route, and are at least remotely reasonable...you should be clean.
Our auto customers didn't complain...they adopted that approach.

 

[Jim Wynne]

Jim

After reviewing the system as it is now I am comfortable with the justification for the extension. I am curious as to what trouble you think may be ahead with this?

For starters, have you, or will you, review the as-found calibration data for all 1100 devices? Sampling doesn't count.

 

[qcman]

We have intervals from monthly up to 3 years depending on intended use, environment and risk of damage. The bulk of and the ones in question carry low risk. I ran this by the auditor conducting our surveillance 2 ISO audit this week ( 1 minor ) and he felt a written directive would be ok for him in a future audit but did say other auditors may have issues with it. As always very good points you make and why I love the Cove.

 

[dwperron]

I hate to be a wet blanket, but I see audit problems.

You don't say what flavor of "ISO" that you will be audited to, so I will go with basic ISO 9001.
As mentioned by Tagin, the following section addresses this problem:

7.1.5.2 Measurement traceability
When measurement traceability is a requirement, or is considered by the organization to be an essential
part of providing confidence in the validity of measurement results, measuring equipment shall be:
a) calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards
traceable to international or national measurement standards; when no such standards exist, the
basis used for calibration or verification shall be retained as documented information;
b) identified in order to determine their status;

b) is the reason why most organizations use calibration labels - they identify the calibrated items and determine their calibration status.
If you have a label that says calibration is valid to 06/01/2021 and it gets used on 08/01/2021 the label says it is not valid to use. An auditor will not take kindly to seeing inaccurate information on a label meant to "determine their status". Face it, you should change the labels so that they are correct. I know you would like an instant fix, but this will be best done as a 2 year process as they come due for calibration.

Yes, you can change calibration intervals. That will open up questions for Section 6.1: Actions to address risks and opportunities
Extending the calibration intervals will increase risk of using an out of tolerance tool, so you will need to address this risk and justify that you have taken the additional risk into account with your products and processes. This risk assessment will need to be documented and evaluated for effectiveness.

 

[Mikey324]

Speaking for myself, I see a lot of risk in potentially producing up to 2 years of nonconforming product, and with 1100 gages, well, that sounds like a big volume of potentially nonconforming product. The costs, the impact to customers, damage to reputation could be enormous.

An auditor may well query you on your process for the last part of 7.1.5.2:

I can't imagine verifying 7.1.5.2 at stated after 2 years.

 

[Mike S.]

How much additional risk is it, really? Worst-case you could be using a gage out of calibration for a year under the current system, or 2 years under the new system. If either happened, it would be a bad deal, so I don't see a huge risk increase.

I always try to have some way to mitigate that kinda risk -- like a quick verification step whenever possible. That way, if my gage goes nuts and out of cal the day after it is calibrated, I could catch it in a day or a week, not a year. A daily or weekly quick check of a micrometer on a gage block, or a standard weight on a scale, or a measure of a "gold unit" on a tester, etc.

 

[Ninja]

FWIW, I've found that most gages I've used tend to fail catastrophically (though I'm sure there are some that simply 'drift').
A drop gage that you know should be about 200um reading 2550um and on remeasure reads -65um because the etched glass cracked.
A CMM measuring 25 inches when the stage is only 8".
In that regard, I agree with Mike S. re risk increase.

FWIW, I've never had an issue with being audited to 7.1.5.2 with cal periods all over the place (up to 10yrs as described above).

 

[dwperron]

My history in the calibration world is an overall 95 to 97% pass rate on calibrations. You are correct, the overall risk is low.
I've also seen the dogs (O2 and moisture sensors) that struggle to meet 50% pass rates, even with reduced intervals.
But I know that through years of collecting the data. I have facts to prove the risk is normally very low.
This string started with a guy who just wanted to double all of his calibration intervals.
Nobody has any idea what risk is involved in this case unless it gets analyzed.
That's a red flag for an audit.

 

[Ninja]

Fair enough. Jim called that out right up front that each individual gage had to be justified for extension.

For 'normal' gages (mics, drop gages, CMM, etc.) I've never seen one fail other than catastrophically (meaning too obvious to not notice).
You are spot on with the chemical gages...we had LEL sensors that drifted weekly and were reset/recalibrated/re-whatevered about once a month. Weren't going to extend them, no-how, no-way.

If "all intervals are hereby doubled", I can see that being problematic in an audit...defensible, but with individual gage data.
If each 'worthy' gage is doubled based on data, and it just so happens to be all of them...I don't see that even being a red flag.