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Using "Particle Size Standard" templates as gauges - How to avoid giving a gauge # while using for process control?


We use a "particle size standard," which is a transparent template with different particle sizes denoted on it (0.25 mm to 2.00 mm in 0.25 mm increments). It is held over a defect to determine its size. Maximum defect sizes are called out on control plans/standards and these particle size standards are used like gauges to verify if the defect size is acceptable.

I'm looking to understand if, per IATF16949, each one of these gauges would need a gauge ID and annual calibrations if used in process control. I can see the argument that ink from the template could be worn off (or dirt/paint could be marked on), making one of the readings inaccurate, but see this as a very unlikely risk and not worth consuming Metrology resources for.

Has anyone had something similar to this addressed in an IATF audit?

Any opinions or perspectives would be appreciated.


My experience with these templates is that they do require a gauge ID and are subject to an initial calibration. It is then documented that due to the stability of the materials used that they do not require scheduled calibrations, Typically they are placed on a visual inspection program to verify that the template is not damaged and the condition is adequate to be used in your process.

For traceability purposes, whenever this template is replaced it should receive a final calibration to assure that it is still within the original tolerances.


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I agree with dw. Another consideration is the transparent material used. Is it thermally stable, or does it expand with increased temperature? Does it swell in high humidity? This could be addressed by an initial stability study.
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