Measurment Discrimination

[rvjones]

I am looking for information on what the insdutry standard is with regard to the accuracy (discrimination) of measurment and test equipment. I am told that generally for tolerances of less than .001 in. measuring instruments should discriminate within 10 %? Any information is greatly appreciated.

[Belanger]

Yes, I think the 10% rule has been around for a long time. If you are talking about physical gages (functional go/no-go gages, etc.) the standard to look to would be ASME Y14.43. In there I know for sure that the 10% rule is discussed, but they are careful to use the word "recommended" rather than the more stringent "shall."

But if you're not talking about functional gages, there are several other ASME standards that intersect with the 10% idea. Check out the follow ASME brochure:

http://fileS.asme.org/Catalog/Codes/PrintBook/25586.pdf

It's a promotional thing for their actual standards regarding measurement uncertainty, and those will cost some $, but hopefully reading the brochure will steer you in the right direction.

[Kelly_Bramble]

10% for inch units, 5% for mm units.....

[rvjones]

Thank you for the information it was very helpful!