ISO 9001:2008 Calibration of Measurement Equipment Requirements

[BradM]

My company has approximately 28 scales that are used to measure products that are at design stage. In other words, our scales are not used for pass/fail. We are ISO 9001:2008 certified, and we decided to calibrate/validate them in-house using different set of weights. Is Statement of Accuracy (that goes along with the set of weight) valid enough to show to our external auditors?
I beleive we are in compliance to the standard. Don't you think?

Please help me.

Thanks,
Chance

Chance, have you performed an uncertainty analysis/accuracy ratio/ etc. to assure you have sufficient standards? There are all kinds of different classes of weights. Too, there are different ways to verify a balance, including corner loads, repeatability, etc.

As far as calibrating your standards, do you have a competent vendor calibrating them? Are you having a lot of failures with your standards? Are you having a lot of failures with the instruments you are calibrating?

So saying, I would be interested to know that your calibration process is in order, effective, and working. That to me, the calibration process being effective, is what your external auditor would be interested about.

 

[Chance]

Chance, have you performed an uncertainty analysis/accuracy ratio/ etc. to assure you have sufficient standards? There are all kinds of different classes of weights. Too, there are different ways to verify a balance, including corner loads, repeatability, etc.

As far as calibrating your standards, do you have a competent vendor calibrating them? Are you having a lot of failures with your standards? Are you having a lot of failures with the instruments you are calibrating?

So saying, I would be interested to know that your calibration process is in order, effective, and working. That to me, the calibration process being effective, is what your external auditor would be interested about.

Thanks for your reply.
We have decided to use +/- 1 accuracy specified in our calibration procedure since it is only used for research purposes not for high precisions. I decided to use Class 6 set of weight that comes with statement of accuracy as proof that we are using set of weight that is traceable to NIST.

We wanted to stop the external calibration to save company money. We don't have any failures that I am aware of.

 

[Al Rosen]

I disagree.

Essentially, if the steel rule/tape measure is used to measure a critical parameter then it will need to be VARIFIED as accurate against a known standard. You will not 'calibrate' it.

That's splitting hairs. Comparing it to a known standard is calibration.

 

[Phil Fields]

I disagree.

Essentially, if the steel rule/tape measure is used to measure a critical parameter then it will need to be VARIFIED as accurate against a known standard. You will not 'calibrate' it.

The statement in the example you give above is also ambiguous and misinforming.
Either it IS or IS NOT critical and will be controlled/verified as required; simple as that!

The TAPE MEASURE Question:
This seems to come up every now and then. Measuring critical dimensions, what is critical ±.0005, ±.005, ±1/32, ±1/2? What accuracy does a Tape measure have, 1/32”? How accurate can the tape measure be read?

In a metal shop environment I would use a tape measure as a reference only tool and not to accept product (most tolerances<.020”). If I was working in an industry where ±1/2” was the norm, than a tape measure might be ok to use to accept final product (that why molding was invented)

Phil

 

[Chance]

Thanks for your reply.
We have decided to use +/- 1 accuracy specified in our calibration procedure since it is only used for research purposes not for high precisions. I decided to use Class 6 set of weight that comes with statement of accuracy as proof that we are using set of weight that is traceable to NIST.

We wanted to stop the external calibration to save company money. We don't have any failures that I am aware of.

I am hoping I would get a reply from a consultant who is kind enough to share his/her expertise.


Chance

 

[Mark Cost]

My previous employer is ISO 9001:2008 certfied. I wrote up the procedure for our scales using NIST traceable weights and this seemed to be okay with the auditor (no findings). I did work into the job instructions (for all units being weighed) the acceptable scale unit numbers to be used. However, another auditor here may be able to be more enlightening than I

 

[Chance]

Mark,

Thanks for your help. In my case I just bought Statement of Accuracy traceable to NIST for my test weights. I built my own internal procedure on how to the calibration.
Can you share with my how did you design your job instructions? I need one.
Thanks,
Chance

 

[Mark Cost]

Sadly, when I left my last employer, the brilliance of my quality prose remained. However, I will do my best at recollecting and get you something ASAP. In the meantime, maybe someone (MARC!!!) might be able to steer you to another document.

 

[Jim Wynne]

What do you use to measure the product you manufacture? Those measuring instruments are what is telling you that the product you fabricated conforms to the requirements. Those instruments need to be calibrated and traceable.

Any measuring instrument used to verify/accept product must be calibrated and records must be available to support the calibration.

I like to know where you see a requirement for (or any mention of) measuring instruments used to verify/accept product in 7.6 of ISO 9001:2008, quoted here with my emphasis:

The organization shall determine the monitoring and measurement to be undertaken and the monitoring and
measuring equipment needed to provide evidence of conformity of product to determined requirements.

The organization shall establish processes to ensure that monitoring and measurement can be carried out and are carried out in a manner that is consistent with the monitoring and measurement requirements.

Where necessary to ensure valid results, measuring equipment shall
a) be calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards; where no such standards exist, the basis used for calibration or verification shall be recorded (see 4.2.4);
b) be adjusted or re-adjusted as necessary;
c) have identification in order to determine its calibration status;
d) be safeguarded from adjustments that would invalidate the measurement result;
e) be protected from damage and deterioration during handling, maintenance and storage

If I use a measurement device to "verify/accept product" that doesn't need calibration "to ensure valid results," there's no requirement in the standard to calibrate. If anyone disagrees with this, please show me the requirement.

 

[Mark Cost]

Jim,
Although I agree with you in theory, I would disagree with using it as a calling card for your argument with an auditor. The statement "Where necessary to ensure valid results" is the real sticker here. It's vague. In my experience (especially when being audited by a customer), the idea of having any measurement equipment near product that is not calibrated sends up red flags. I guess the question is, "Is it better to have a procedure that allows for these non-calibrated/non-validated tools or to have all measurement equipment calibrated/validated?" I would go with the latter for two reasons: It eliminates the question "How do you ensure these items are not used to verify product?" and; Auditors see it as good practice.
Thanks,
Mark