Not a measurement standard?

[[Aa...]]

On many occasions, I've seen comments on this forum to the effect "Y14.5 is not a measurement standard. It's a product definition standard," as an excuse to not be precise in the application of Y14.5. But to me this seems like a distinction without a difference. What is the point of giving a definition of a product if it's not to determine the difference between a conforming and nonconforming product? And what is the point of metrology if it is not to determine to which of those categories it belongs? If, then, one's approach to metrology does not apply the correct interpretation of the product definition according to the standard, how can one claim to be effectively measuring the product to determine its conformity to the product definition and tolerances?

[[Cl...]]

Found this statement on-line.

"The Y14.5 standard is considered the authoritative guideline for the
design language of geometric dimensioning and tolerancing (GD&T.)"

Is the key word here "Guideline"? So, guide or standard?

[[Aa...]]

So are we to treat it like the "Pirate Code"? Is a dictionary, then, only a guideline for what meanings to apply to words and not a standard? But the point of a dictionary is to have something we can all agree on. To give a ridiculous illustration, if our customer described the assembly they wanted as containing a gauge pin, and by "gauge pin", they actually meant "machine gun", we would have some trouble in final inspection determining whether we were sending them what they ordered.

[[Cl...]]

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I was just playing devils advocate with that response. I believe it is and should be treated as a measurement standard.

[[Aa...]]

The cover page says it's "An International Standard".

[[Ja...]]

I think the intention of the statement "Y14.5 is not a measurement standard" is that it does not tell you how to measure, it tells you what to measure. Caliper, Micrometer, CMM, Vision machine, number of points taken, is all up to you to determine the best measurement method that will conform to Y14.5.

[[Aa...]]

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If that is all that is meant, then I have to agree. CMM is often the best method because it is so flexible in that a virtually limitless amount of data can be collected, and if it is used correctly, it can be used to accurately assess conformity.

[[Ch...]]

Some people on here love it when I get on here and remind them(just fun and games here folks) that Y14.5 is not intended to define measurement methods and that in fact, a measurement method can never "conform" to Y14.5.

See attached for explanation.

CMM-GDT_Measurement_Planning_Hand-Out.pdf

[[Aa...]]

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I don't disagree with you, there. I only want to contend that when the question is whether or not a measurand complies with a specification defined in the language of Y14.5, correctly interpreting the specification in the language of Y14.5 is critical. This is what is meant by "Specification Uncertainty" in ISO/TS 17450-2.

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