"Internal Calibration" using other Calibrated Equipment

H

Haim Moshe

Hello Everyone!
I am new to this forum but had a the chance to sniff around lately.

We have a model shop in company which handles only R&D requests.
it is a wonderfull workshop with top edge equipment and a lot of measuring equipment

Until lately they never calibrated the TE saying it was for R&D purposes and as such it is not required.

Eventualy they understood the need for calibration and so we are now calibrating the majority of the stuff.

However; there are some TEs for which we are doing "Internal Calibrating" using other calibrated equipment.

we are keeping the reference equipment in a closet and the room is being air conditioned almost 24/7 (with measurments indicating RT and 50%RH)

My question is - it is allowed?

Haim
 
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S

SteveK

Re: "Internal Calibrating"

Hi Haim,

Welcome on board!

In answer to your question - I certainly hope so, this is what we do. We use calibrated 'Master' gauges to calibrate gauges on the shop floor - these are locked away. Not had any problems with this during audits. It is traceability that is the ultimate requirement IMO.

Steve
 
H

Haim Moshe

Re: "Internal Calibrating"

Thanks Steve

I felt it is OK but wanted something to confirm this
I reviewed the ISO9000 req. but it is worthless in this matter
ISO17025 is an killer

How often you are calibrating your masters? annually?

Haim
 

BradM

Leader
Admin
Hello Haim!:bigwave:

I do have some questions here in regards to your question.

As Steve said, "yes" it's OK to perform calibrations in in-house. Apart from that, you might want to answer some questions to assure you have an adequate process to do them.

  1. Do you have a valid procedure to do the work?
  2. Are the operators trained on the procedure and have the knowledge to do the work?
  3. You state you have environmental controls. Are they sufficient to assure there is no impact/effect from the environment on the calibrations and/or standards?
  4. Have you established some plan of remedial action if the standard is found out of tolerance? This may also involve risk assessment and such.
  5. Are all the results being adequately documented and reviewed?
  6. Are your standards of sufficient accuracy?
I know that's a lot of questions.:D I was just pulling some out of the air. There may be more.

You might consider getting ISO10012 and assuring your process meets those requirements:
http://www.iso.org/iso/catalogue_detail?csnumber=26033

17025 is a fairly stringent requirement, but is a great one to follow. You might consider reading it and verifying that your process satisfies its requirements.

Hope this helps.:)
 
S

SteveK

Hi again Haim,

All our master gauges are calibrated annually by a calibration/test house. Obviously we retain the certificates for the masters. The other things Brad asks for is spot on. After an audit I had a minor NC because I did not state what we would do in our procedure if a gauge came back and it was found out of calibration.

Steve
 
D

Duke Okes

Of course you need to ensure that your internal calibration devices have the appropriate accuracy/precision in order to accomplish the required accuracy/precision of the final device.
 
G

George Weiss

The original question of calibration did not reference an ISO STD, but 9001 is assumed.
There is not much help there, because you are in the ISO realm of "write what you do", and then "do as you write". There are some steps in the completeness and correctness of the process. Your comment about ISO-17025:2005 being an unwritten OMG is understandable. There is another group of guidance documents, which are old, but put you on a good course. MIL STD 45662, costs $0, and is easily reviewed, and puts out a good collection of methodologies. Referring to this standard might be a good first step in a circling of what to do. One of the draw-backs to doing a better job, and referencing more documents, is a mushrooming of technicalities. An evaluation of your over-all calibration plan level being: 1) a few calipers, 2) some small meters and power supplies, or 3) a developing variety of equipment and tools. Making a simple procedure and not involving all the MIL STD 45662, Z540.1, Z540.3, ISO-17025 requirements, might make the most sense. You might find that you have a measurement need well below the ability of the caliper’s abilities. Testing to your limited needs is another means of not over killing the "performance verification" of the caliper, or other item. Looking at, and reviewing the mentioned standards will give you a likely down-stream point depending how your business develops.
 

apestate

Quite Involved in Discussions
The metrology industry and regulations define traceability as an unbroken chain of measurements going back to national standards, each accompanied with a statement of uncertainty.

Measurement uncertainty is the key to traceability. If I calibrate my own gage blocks, I might create a calculation of measurement uncertainty. I might even be right... but what guarantee do you have that I'm not just some hack?

Therefore, ISO 17025 and laboratory accreditation gives you some universal assurance that the calibration and measurement uncertainty calculation has been done right.

Now, let's say you send your gage blocks to an accredited lab who have adequate capabilities. They are traceable to the standard inch as defined by NIST.

Now, we only really need to calibrate our tools so we can measure our products. We don't need to calibrate our products, so that THEY are traceable to national standards. We simply need to qualify them as good or bad. Therefore, it's OK to skip the measurement uncertainty when you calibrate your calipers, micrometers, bore gages, comparator, indicator, etc.

According to the definition of traceability, you can calibrate your hand tools as long as the masters you are using have been calibrated and accompanied with a statement of inaccuracy estimation.

You can't calibrate a micrometer "in-house" and then use that micrometer to calibrate a caliper's ID jaws. However, if you send that micrometer to an accredited laboratory first, you can use it to calibrate the ID jaws.

That's the rule as I understand it. :>
 
G

George Weiss

The previous post is a very good ISO-17025:2005 posture. All of the descriptions would be of full concern if you are attempting to comply with ISO-17025:2005. If you do go done this course, you might be over killing your needs unless you are willing to go the fully route and become accredited. Claiming 17025 compliance is a flag with no value, and lots of effort. You are claiming ISO 9001, and want a course to follow. Maybe just posting a thread asking for a procedure to verify you gages with your cabinet stored standard.
Have you thought of just marking the gages "reference only", and then just periodically checking them as a functional confidence check, with a date and test value checklist form?.
 
H

Haim Moshe

Thank you all :thanx: for the contributing information. I will summerize and prepare some doc on the matter. I will post it for review and comments. again thx
 
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