Refining Note

[SeasonLee]

If the planar surface is a sealing surface and has been designated as a primary datum feature, in order to prevent the distortion direction, we may add a refining note underneath the FCF, may I ask which note is reasonable and will meet the functional requirement? Please ref to the figure below for details.

Season

 

[Tarator]

SeasonLee,

Typically, "SHALL NOT BE CONVEX" is used to prevent a "rocking chair" condition. However, in your case, either option may not prevent that. You may want to add some restraining or consider using datum targets.

 

[SeasonLee]

Thanks for your input, Tarator.
For ISO standard, we can see this term very often NC(Not Convex).

Season

 

[greenimi]

Season,

For ISO standard, we can see this term very often NC(Not Convex).

Wasn't NC term removed from the latest ISO standard?

 

[greenimi]

A.3 Former practice from ISO 1101:2012
The following drawing indications were described in ISO 1101:2012. Their use in practice has shown that their interpretation was ambiguous. Therefore, these drawing indications should no longer be used.
A.3.1 It was a former practice to use the NC specification element to indicate that the toleranced feature should be “non-convex”, see Figure A.4. This specification element is no longer used, because it is ambiguous what exactly constitutes a non-convex feature, i.e. how close to the edge of the feature should a plane contact the feature for it to be considered non-convex. There is no replacement for this indication in this document, since it is a qualitative concept. If needed, it can be added as a note on the drawing.

 

[SeasonLee]

Wasn't NC term removed from the latest ISO standard?

That's I really don't know, and I noticed this was changed at 2017 edition. Thanks for the information, but the figure I posted is per ASME standard.

Season