Managing Coincidence Constraint

This task consists of applying a coincidence constraint between two faces and modifying the constraint specifications. See Coincidence Constraints reference.
Before constraining the desired components, make sure it belongs to a component defined as active (the active component is blue-framed and underlined).
Open the Constraint1.CATProduct document.
  1. Click the Coincidence Constraint icon:

  1. Select the face to be constrained, that is the red face as shown.

The Assistant message box appears as shown below if it is the first time.

  1. Select the “Do not prompt in future checkbox" and click the Close button.

  1. Select the second face to be constrained, that is the blue circular face in the direction opposite to the red face.


Green arrows appear on the selected faces:

  • They appear only when the orientation of the selected elements is taken into account in the coincident constraint and indicate how the selected elements is designed during the assembly update.

  • The arrow on the first selected element is the reference arrow and its orientation cannot be modified.

  • Double-clicking of any of arrows changes the orientation of the arrow on the second selected element. See also constraint orientation in the Constraint Properties dialog box.

  • Arrow orientations are kept in the constraint and are displayed as they have been specified when editing the constraint.


The Constraint Definition dialog box appears.

  1. Click on the More button.

    The following dialog box appears.


The Constraint Properties dialog box displays the constraints properties:

  • The constraint type icon:

  • The status is represented by a traffic lights icon:

    • verified.

    • impossible.

    • not updated.

    • broken.

  • Name: the constraint name, here Concidence.8

  • Supporting Elements: the type of geometrical elements involved in the constraint, their related components, and their connection status are displayed.

  • Orientation: appear only when the orientation of the selected elements are taken into account in the coincident constraint:

    • Undefined: (the application computes the best solution)

    • Same: geometrical element orientations are the same.

    • Opposite: geometrical element orientations are opposite.

  1. Click OK to create the coincidence constraint.

  1. Update the assembly if needed.

  • The application chooses which component is to be moved to adopt its new position. As the assembly is not iso-constrained, any component can be moved. In other words, you cannot control which components can be moved.

  • Green graphic symbols are displayed in the geometry area to indicate that this constraint has been defined.

  • The constraint is added to the specification tree too.

Graphic symbols used for constraints can be customized. For more information, refer to Customizing Constraint Appearance.