A minimum material envelope as a datum feature simulator 1

[Burunduk]

I noticed that para. 4.5.1 in Y14.5-2009 lists "(d) a minimum material envelope" as an example of a datum feature simulator. How is this specified on the drawing and what kind of applications is it useful for?
I thought that for datum features referenced RMB, the UAME (in case of primary) or RAME (in case of secondary/tertiary) is the datum feature simulator. For datum features referenced with material boundary modifiers, the simulator is the MMB or LMB boundary. Never have I seen how and when a UAMME/RAMME datum feature simulator is invoked...

 

[pmarc]

Dean,
As Evan said, the envelope is inside the material therefore cannot be considered "mating". See definitions 1.3.25 and 1.3.26 in Y14.5-2009.

 

[Dean Watts]

pmarc,

Your example might be interpreted/decoded by some to be for the UAMME, but I think that view would not be unanimous. For the examples shown in 4-35 do you know of any way to specify that the UAMME would be used to establish a datum? I don't know of any way to do this, so I think in every case, since Y14.5 does not give us a way to do this, we must have a note.

Dean

http://www.validate-3d.com

 

[Belanger]

Would the analogy of virtual condition vs. resultant condition be helpful in any way?
VC is for mating, while RC is for material preservation. Those two ideas don't seem to cause controversy (however, they are just terms, and never symbolized on a drawing, which seems to be the issue here).


John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[Dean Watts]

John-Paul,

Since VC is the in-material boundary when LMC is specified, I think we need another modifier or two instead. It might just be best to use the S+ and S- that Bill Tandler proposes.

Regarding our confusing set of boundary names, I think "Worst-case", "Inner", "Outer", "Virtual condition", and "Resultant condition" should all be deleted from Y14.5 and we should live on (enjoy actually) "Maximum material boundary" and "Least material boundary" instead of those 5 other terms.

Dean

http://www.validate-3d.com