Hi All,
First post, so go easy on me!
I have a part with six nominally co-planar mounting bosses over a total area of approximately 450mm x 450mm.
I have received feedback from the supplier that they can hold the "flatness" of these bosses (their terminology, not mine) to ±0.05mm per 100 x 100mm area. Thus they propose an overall "flatness" tolerance of ±0.2mm for the faces of these bosses. This (just about) acceptable to us, so we would like to capture this on our piece part drawing.
I would prefer to use Profile of a Surface in place of a flatness tolerance for a couple of reasons; the ability to control position (using a basic dimension) within the same tolerance and also, most importantly, the implicit inclusion of co-planarity provided by Profile of a Surface (Sec. 8.4.1.1 of ASME Y14.5)
I am proposing setting a datum plane (Z) to be co-planar with all six boss faces and then applying one of the attached geometric tolerances to the surfaces. (please see attached image)
The issue that I am having is that ProEngineer only offers "per unit length" as an option for Profile of a Surface, not "per unit area" (which is offered when creating a flatness tolerance, for example).
Is "per unit area" not an acceptable modifier to a Profile of a Surface tolerance?
Logically I think it should be allowed, but can find no explicit reference to it in ASME Y14.5 (which does mention per unit length in 8.3.2.2.).
I have seen it used in other places ( for example), but wanted to come here and solicit some other expert opinions.
Thanks in advance for any help you are able to provide!
First post, so go easy on me!
I have a part with six nominally co-planar mounting bosses over a total area of approximately 450mm x 450mm.
I have received feedback from the supplier that they can hold the "flatness" of these bosses (their terminology, not mine) to ±0.05mm per 100 x 100mm area. Thus they propose an overall "flatness" tolerance of ±0.2mm for the faces of these bosses. This (just about) acceptable to us, so we would like to capture this on our piece part drawing.
I would prefer to use Profile of a Surface in place of a flatness tolerance for a couple of reasons; the ability to control position (using a basic dimension) within the same tolerance and also, most importantly, the implicit inclusion of co-planarity provided by Profile of a Surface (Sec. 8.4.1.1 of ASME Y14.5)
I am proposing setting a datum plane (Z) to be co-planar with all six boss faces and then applying one of the attached geometric tolerances to the surfaces. (please see attached image)
The issue that I am having is that ProEngineer only offers "per unit length" as an option for Profile of a Surface, not "per unit area" (which is offered when creating a flatness tolerance, for example).
Is "per unit area" not an acceptable modifier to a Profile of a Surface tolerance?
Logically I think it should be allowed, but can find no explicit reference to it in ASME Y14.5 (which does mention per unit length in 8.3.2.2.).
I have seen it used in other places ( for example), but wanted to come here and solicit some other expert opinions.
Thanks in advance for any help you are able to provide!
