NX Mass Properties is reporting a negative value for top-level assembly

Mass Properties is reporting a negative value for top level assembly from Assembly Cut.

Please see NX video on Assembly Cut and Negative Mass along with the detailed steps provided below.

Mass Properties is Reporting a Negative Value for Top-Level; Assembly

Demonstrating Negative Mass Properties

1.       Open an Assembly.

2.       Choose the Assemblies tab -> Base group -> Assemble.

3.       In the Assemble window, select the desired part.

4.       Click OK.

5.       In the Top Border Bar, select Menu -> Insert -> Design Feature -> Sphere.

6.       In the Top Border Bar, change the Selection Scope to Entire Assembly.

7.       Select the desired point on the model.

8.       Click OK.

9.       Choose the Home tab -> Base group -> More -> Assembly Cut.

10.   Select the bodies as desired.

-          Note: The Hide Tool option is checked by default.

11.   Choose the Analysis tab -> Mass Properties group -> Show Mass Properties Panels.

12.   In the Assembly Navigator, select the Top-Level Assembly.

13.   In the Mass Properties panel, select Assembly Only.

14.   The negative mass can now be viewed in the Mass row.

Why Mass Properties Reports a Negative Value

Mass Properties takes its values from the Top-Level assembly. In the demonstration above, the Top-Level assembly is empty before the cut is applied, therefore the mass of the model isn’t factored into the calculations. Once the cut is applied, the data provided by the Assembly Cut is retrieved by the Mass Properties table. The negative value that appears in the table is the amount of the model that is removed by the Assembly cut.