Hi all, I was wondering if anybody could help me out on a quick question regarding the laboratory requirements for a calibration house (7.6.3.2)

I have a thermocouple manufacturer and their calibration method is to provide a calibration based upon the batch calibration of the wire, done by a laboratory accredited to ISO 17025. These thermocouples will be shipped after an internal reference check with the standard reference thermocouple which is done by the OEM and who are not accredited to ISO 17025 laboratory. The equipment they use is tracable to national standards. The requirement from TS16949:2002 is that an external laboratory should be either:
- acceptable to the customer
- be accredited to ISO/IEC 17025 or national equivalent

The equipment in question is a thermocouple and qualified laboratories are available and as such the clause that allows the equipment manufacturer to perform the check does not apply.

Does anybody know if the batch wire calibration by an ISO/IEC 17025 accredited lab and internal reference check by the OEM would address the requirements of clause 7.6.3.2.

:thanks:

Hello there!:bigwave: I'm a little confused, so help me out a bit...

You state the lab performing the calibration on the spool is accredited:

Hi all, I was wondering if anybody could help me out on a quick question regarding the laboratory requirements for a calibration house (7.6.3.2)

I have a thermocouple manufacturer and their calibration method is to provide a calibration based upon the batch calibration of the wire, done by a laboratory accredited to ISO 17025.

But then after the T/C's are cut from the spool, another company (not accredited is checking them?):

These thermocouples will be shipped after an internal reference check with the standard reference thermocouple which is done by the OEM and who are not accredited to ISO 17025 laboratory. The equipment they use is tracable to national standards.

And then you are wondering if you satisfied a clause:

The equipment in question is a thermocouple and qualified laboratories are available and as such the clause that allows the equipment manufacturer to perform the check does not apply.



NOTE: I do not work in automotive, so discount anything here as such.

It is typical in other industries to calibrate both ends of thermocouple wire and apply those errors to the entire roll. Typically you want to get special limits of error wire, and keep in mind that they wires have a limited shelf life.

I don't understand why you are perfoming two verifications: the initial one on the roll, and then the subsequent verification. Too, what about performing the verifications yourself? You could pick up a small furnace calibrator and verify your probes prior to use? You could get a standard thermocouple for traceability if you would like.

Again, not sure about the clause, but it sounds like you are paying for double service on your thermocouples.

Hi Thanks for the reply. I will try to explain

The requirement in TS16949 is that any external laboratory must be accrediated to ISO IEC 17025 or if not approved by the customer. If an accrediated external lab isnt available then the OEM can be used. In this case there are many labs that can calibrate thermocouples so there cannot use this caveat.

Therefore to try and get around this the OEM is sending out a batch wire to be calibrated by an accrediated lab. Once this is OK these assemble the thermocouples and perform a reference check to make sure that the function OK. My worry is whether this reference check needs to be done by an accredited laboratory or if this check is OK at the OEM.

I would have to say it would satisfy it. I do internal calibrations for a company and never get calibrated wire from outside. The company is traceable to their required standards for manufacturing, and I do any necessary calibrations here with either T/C oven or multifunction calibrator, which both are traceable to NIST, which in this case is third party and traceable.

The OEM is acceptable should they perform calibration on their product.
Should it be commercial lab, it shall be an ISO17025 Accredited.

For your case of the thermocouples, the OEM certifies that their spool (thermocouple wires) was manufactured within the specifications. However, once the wire is cut and made into thermocouple sensors, then it requires individual calibration. Wherein a lot of ISO1705 commercial labs are accredited should you don't have your internal capability.

Therefore to try and get around this the OEM is sending out a batch wire to be calibrated by an accredited lab.

Here is my opinion :2cents:: Since the weld is a key factor in the thermocouple function, as well as a good termination in the connector, its hard to think one would be satisfied with calibrating the wire alone. Now, if you performed a calibration, documenting linearity, verifying to the accepted specification for that thermocouple, you may be OK - as long as it is a part of your scope of accreditation.

Again, that is my opinion...:cool:

Here is my opinion :2cents:: Since the weld is a key factor in the thermocouple function, as well as a good termination in the connector, its hard to think one would be satisfied with calibrating the wire alone. Now, if you performed a calibration, documenting linearity, verifying to the accepted specification for that thermocouple, you may be OK - as long as it is a part of your scope of accreditation.

Again, that is my opinion...:cool:

That's a good point, Bob. When I was in aerospace, the above procedure was acceptable (verifying both ends of the thermocouple roll). The theory being that the largest error would come from the inconsistency within the materials making up the wire.

I think it's fine to get a certified roll of wire. I would still buy a furnace/calibrator and a standard probe and check the loop. This way you have verified the system (with the weld like you mention) just prior to using it.

Given your test application, pick the best classification of wire. So many times people grab J wire, when a much more accurate class may meet their temp. ranges. Also, go ahead and pay for special limits of error wire.

A badly oxidized weld can give you very inconsistent results. Most of the T/C failures I have seen are in the weld, followed by the connector. So, I base it on my experience...and over/under cooked product....:cool: