mass properties discrepancy in Assemblies

[m3rd]

Hi all,

I am attempting to locate the CG of an assembly in SW 2011. It's essentially a box with a lid and 4 mounting brackets- lid and box are Al6061-T6, and brackets are plain carbon steel. When I call up the mass properties for the assembly it's mass and volume is about 1.7 times the respective values of the six individual parts combined. Any ideas on why this is? The box is hollow; is it including the volume and "mass" of the interior?

Also, why is density in the "mass properties" window showing 0 for all of the parts? Why does it not list the density for the materials defined for each part? It does show, "grayed out", the correct density value under the "options" window.

Thanks

 

[CorBlimeyLimey]

Check to make sure the Assigned mass properties has not been enabled in the Mass Properties dialogue box.

 

[m3rd]

I checked; Assigned mass properties has not been enabled in the Mass Properties dialogue box.

 

[CorBlimeyLimey]

Can you ZIP & post the files here for review?

 

[m3rd]

Never mind. I found the problem. I have inadvertently mirrored a part.

 

[gwubs]

We have found that assembly cuts can cause the mass of a model to INCREASE (yes that's right, increase). Suppressing the cut and umsuppressing has usually corrected the problem. Still it is a strange thing... As with your miirred part in the model, if you look long enough, you do find the culprit.