Drawing Feature Question

[818_qualityguy]

I have a question regarding this drawing. My production guy is interpreting this completely different than our customer.

Our production guy is reading this as the ID should be maintain on average the required dimension of 9.474 - 9.478 with the roundness of .010" free state allowing the ID to move outside required tolerance.

 

[Jim Wynne]

I have a question regarding this drawing. My production guy is interpreting this completely different than our customer.

Our production guy is reading this as the ID should be maintain on average the required dimension of 9.474 - 9.478 with the roundness of .010" free state allowing the ID to move outside required tolerance.

The way I see it, the diameter requirement must be met within the roundness limit. In other words, I think your production guy is wrong. As an aside, the "free state" qualifier seems to indicate that the part is flexible, which might make measuring the roundness pretty difficult.

 

[818_qualityguy]

The way I see it, the diameter requirement must be met within the roundness limit. In other words, I think your production guy is wrong. As an aside, the "free state" qualifier seems to indicate that the part is flexible, which might make measuring the roundness pretty difficult.

I agree, however its strange that the roundness allowed is higher tolerance then the diameter requirement.

 

[Cari Spears]

The roundness and the diameter size must both be within tolerance. That said, if the tolerance on the size is only .003", then if the roundness is as far out as .010", the hole size would be out of tolerance. Form tolerances are a refinement of size tolerances.

edit: I posted a few seconds after your post ^. Maybe it's a typo - maybe it is supposed to be round within .001". I'd ask the customer if you're unable to convince your production guy that the hole must be within tolerance, not "on average".

 

[818_qualityguy]

The roundness and the diameter size must both be within tolerance. That said, if the tolerance on the size is only .003", then if the roundness is as far out as .010", the hole size would be out of tolerance. Form tolerances are a refinement of size tolerances.

edit: I posted a few seconds after your post ^. It is not only strange, it's not correct. I think it may even be a typo - maybe it is supposed to be round within .001". I'd ask the customer if you're unable to convince your production guy that the hole must be within tolerance, not "on average".

The way I see it, the diameter requirement must be met within the roundness limit. In other words, I think your production guy is wrong. As an aside, the "free state" qualifier seems to indicate that the part is flexible, which might make measuring the roundness pretty difficult.

From production manager: The fact that it specifically calls out "free state" means that the part can be outside of tolerance when it is in a free state. The part only needs to be within diameter tolerance once constrained. Generally they utilize this call out for non rigid parts, however with the stress from this part the material will move during internal stress created during machining. See:

Generally, geometric tolerance applies to rigid parts. For parts that deform beyond size tolerance or geometric tolerance in a free state, you will write after the geometric tolerance in the feature control frame to indicate that the part is a non-rigid target.
“F” stands for “free state,” and means to apply the tolerance under a free state.

 

[Miner]

I agree with the interpretation of the production manager. The diameter applies to the part in a constrained state while the roundness applies in a free state. Take an o-ring as an example: Diameter is critical in order to seat in the retention groove and seal. However, it can be out of round within limits and still be easily installed.

 

[Cari Spears]

Well, I learned something new today! I didn't even consider o-rings or other types of flexible products. I saw the anodize note and my mind went its own way. Is this a thin little stamping or something?

When we have wet noodle tools or parts, we are often directed by the drawing where to clamp down while we're measuring. However, if it says "free state", that means we have to measure it in its free state and everything has to be within tolerance.

 

[Miner]

Well, I learned something new today! I didn't even consider o-rings or other types of flexible products.

I spent 15 years dealing with rubber product (e.g., seals, gaskets, weatherstrips, vibration isolation products, etc.) for automotive.

 

[Cari Spears]

I'm interested in what the op's product is. Flexible, but anodized...