Independency Principle Method - ISO_8015 – 2011

[[Ke...]]

I'm not too familiar with all of the ISO spec details. It has been asked whether an air gage is able to satisfy the Independency Principle Method requirement, or whether the measurement method must be a 2 point contact/diameter evaluation.

Any insight is appreciated

Thanks!

[[Ri...]]

This is the biggest difference between ISO and ASME (imo).

8015 states that "All requirements on the drawing have to be fulfilled independently from each other. The size tolerance does not limit the form deviation."

So if the Envelope requirement is not invoked, then only all the local sizes (2 point measurements) must lie between the the limits of size.

[[Da...]]

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Check ISO 14405-1:2016 paragraph 4 Specification modifiers and symbols and choose (modify) your destiny :)

[[Ke...]]

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Would you agree with this statement (Regarding the use of an air gage):
"An air gage would satisfy neither the Envelope requirement, nor the independence principle (using local 2pt measurements), as an air gage would rovide as average result, which is most similar to a LSQ evaluation, using a CMM."

[[Ri...]]

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Assuming it is a 3 port or more, that would be a correct statement.

[[Da...]]

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Those 2 are surely correct, 3rd one - I can't get my head around, but I'm not using them.

You are talking about https://www.qualitymag.com/articles/88856-quality-101--all-about-air-gages of course?

edit: thanks Richard