Center of Mass Points in Assemblies

You can add a Center of Mass (COM) point to an assembly. COM points added in component files also appear in the assembly.

The position of the COM point updates when the model's center of mass changes. For example, the position of the COM point updates as you add, modify, delete, or suppress components or add or delete assembly features. The COM point can be useful when you are designing assemblies requiring balanced mass (for example, to avoid excessive vibration).

In an active assembly, operations for the center of mass and equations linked to mass properties are updated only when they take 0.5 seconds or less. If the update takes more than 0.5 seconds, the center of mass and equations are marked with , and are not updated until you initiate a rebuild manually.

The calculation of the center of mass includes:
  • Hidden components
  • Lightweight components. However, COM and COMR points created in the component files of lightweight components are not visible in the parent assembly.
To exclude a component from the calculation of center of mass, make it an envelope component.

You can mate to the COM points of an assembly’s components in distance, coincident, and concentric mates. You cannot mate to the COM point of the assembly itself.

If you add COM points or Center of Mass Reference (COMR) points in component files, the points appear in the parent assembly:
center_of_mass_feature_component_part.png Center of Mass, part Indicates the center of mass of a component that is a part. Defined in the part document.
center_of_mass_feature_component_subassembly.png Center of Mass, subassembly Indicates the center of mass of a component that is a subassembly. Defined in the subassembly document.
center_of_mass_part_overridden.gif Center of Mass, part, user-defined In an assembly, indicates a user-defined center of mass of a component that is a part. Defined in the part document, in the Override Mass Properties dialog box.
center_of_mass_subassy_overridden.gif Center of Mass, subassembly, user-defined In an assembly, indicates a user-defined center of mass of a component that is a subassembly. Defined in the subassembly document, in the Override Mass Properties dialog box.
COM_reference_point_feature_GA.gif Center of Mass Reference Point Indicates the center of mass of the features above the point in the FeatureManager design tree of the part.

For example, in this assembly, center_of_mass_feature.png indicates the center of mass of the assembly, and center_of_mass_feature_component_part.png indicates the centers of mass of three component parts:

center_of_mass_assembly_components.png

If the COM and COMR points are not visible, click View Center of Mass Tool_View_Center_of_Mass (View toolbar) or View > Hide/Show > Center of Mass.