Is NIST traceability required if a Refractometer calibration is done in-house?

#1
I have a refractometer which we use for measuring the quench tank solution in our Forging process.

We measure forging hardness which is the quality check on the forging however we also measure the quench solution % with the refractometer.

The refractometer is scheduled for a yearly calibration where it is sent out to a calibration lab, but I want to bring this internal and have the calibration done in house.

We are ISO 9001 certified and this is a process check not a quality check.

Considering ISO 9001 and the process, do I need the refractometer to be NIST trace-able?

Thanks for reading and replying!
Jen
:magic:
 

Ajit Basrur

Staff member
Admin
#2
Re: If NIST traceability required if Refractometer calibration is done inhouse ?

All calibrations should have traceability to NIST even if the calibration is done inhouse.
 
#3
Re: If NIST traceability required if Refractometer calibration is done inhouse ?

We are ISO 9001 certified and this is a process check not a quality check.

Considering ISO 9001 and the process, do I need the refractometer to be NIST trace-able? :
Why do it, if it's NOT a quality check? What are you doing with the measurement data? If it's the equivalent of sticking your finger under a tap to test how cold/hot the water is then it probably doesn't need a calibration - if you are relying on the hardness value achieved (ultimately) to show "quality". If you can correlate the bath temp to effectively achieving hardness, then it SHOULD be a formal check and, hence defined as a quality activity for process control.
 

Jen Kirley

Quality and Auditing Expert
Staff member
Admin
#4
Re: If NIST traceability required if Refractometer calibration is done inhouse ?

Aside from 7.5.1 asking us to carry out production under controlled conditions, if your instrument is used to help keep a process in control do you still want to have faith in the instrument's readings?
 
#5
Re: If NIST traceability required if Refractometer calibration is done inhouse ?

:thanx:

I will purchase NIST refractometer calibration standards. This way I can do calibration in house.

Thanks,

Jen
 
#6
Re: If NIST traceability required if Refractometer calibration is done inhouse ?

:thanx:

I will purchase NIST refractometer calibration standards. This way I can do calibration in house.

Thanks,

Jen
Do you have the people with the competency to perform such a calibration. You MAY find that it's still more (cost) effective to have it done by a lab. Alternatively, if you're checking just a few data points why not have a lab simply verify it against a master (comparitor type check). Maybe talk with the lab you use rather than (potentially) open a can of worms which actually ends up costing more than you intended to save...
 

Jen Kirley

Quality and Auditing Expert
Staff member
Admin
#7
Andy is right that the matter of controlling a quench bath may not be so simple as controlling quenchant and water ratios with a refractometer, calibration for which could be similar to that of pH meters in that it is zeroed when immersed in a standard solution, in this case possibly distilled water. A paper titled IMPORTANCE OF QUENCH BATH MAINTENANCE discusses impurities and their effects on forging quality. Error can also be introduced into the Refractive Index by contamination like salts and scales in the system.
 

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