Gauge R&R on Vernier Calipers used to Measure 5 CTQ Features

[validationeng]

Hi all,

I have a question which relates to a variable data gauge R&R on a vernier calipers. The unit (it is a titanium knee) that the calipers will routinely measure has 5 seperate features / profiles that need measuring. These are all CTQ features as called out on the drawing.

The question is do I need to do an R&R study on all 5 of those CTQ features seperately or can I rationalize and maybe check one feature as part of the gauge R&R ....perhaps the feature with the smallest tolerance. Would the successful gauge R&R completion of this one feature (% tolerance) then cover the other 4 features as well ??

Appreciate any input /advice here.

Thanks

[dickgent]

You can use pennies, quarters, dimes or nickels (diameter; thickness, etc) for all that matters. It is about the gage, operator and the process -- not the part. What does a GR&R tell you ?..... How much of the tolerance the gage system consumes. A percentage of total tolerance.

Regards,

[Ninja]

In Reply to Parent Post by dickgent

You can use pennies, quarters, dimes or nickels (diameter; thickness, etc) for all that matters. It is about the gage, operator and the process -- not the part. What does a GR&R tell you ?..... How much of the tolerance the gage system consumes. A percentage of total tolerance.

...but with the perspective of the range of use of the gage.

If the features are all nearly identical (all OD's for example) run the GRR on the largest and the smallest. Pass both and you have a good case for not GRR'ing the in-betweens.

If two features are OD's, one is an ID and two are lengths...GRR each type separately since it is a different use of the gage.

You aren't showing just how much tolerance the gage consumes...but how much that particular way of using the gage consumes.
If you spec the diameter of the pennies, and the thickness, I would want to see two separate GRR's.

One big thing to take into account: What does your customer or regulatory board require?

[Jim Wynne]

In Reply to Parent Post by dickgent

You can use pennies, quarters, dimes or nickels (diameter; thickness, etc) for all that matters. It is about the gage, operator and the process -- not the part. What does a GR&R tell you ?..... How much of the tolerance the gage system consumes. A percentage of total tolerance.

Regards,

The purpose of any sort of MSA, including GR&R, is to determine whether or not the measurement system is appropriate for the task at hand, and the task at hand is almost always measurement of product. The fact that a gage might be perfectly acceptable for measuring one part characteristic doesn't mean that it will be appropriate for all part characteristics, even if intuition makes it seem so.

[Jim Wynne]

In Reply to Parent Post by validationeng

Hi all,

I have a question which relates to a variable data gauge R&R on a vernier calipers. The unit (it is a titanium knee) that the calipers will routinely measure has 5 seperate features / profiles that need measuring. These are all CTQ features as called out on the drawing.

The question is do I need to do an R&R study on all 5 of those CTQ features seperately or can I rationalize and maybe check one feature as part of the gauge R&R ....perhaps the feature with the smallest tolerance. Would the successful gauge R&R completion of this one feature (% tolerance) then cover the other 4 features as well ??

Appreciate any input /advice here.

Thanks

One of our resident MSA experts, Miner, has a great series of Cove blog posts on the subject, including Creating Gauge Families. Have a look--it's the good stuff.

[validationeng]

Guys, thanks for the posts, plenty of food for thought.