Creating Remove Face Features

When parts are far too complex for finite elements analyses, there is a way of making them more simple. This task shows you how to simplify a part by removing some of its faces.
Open the Update.CATPart document. As the Remove Face capability only deals with the geometry of the part, not the history of its design, you can use it for imported parts, like in the following scenario, or Version 4 parts.

  1. Click Remove Face  .
    The Remove Face Definition dialog box appears.

  2. Select the inner face as the face to be removed.
    The face turns purple indicating that it will be removed.


    The following contextual commands are available from the Faces to remove field:

    • Clear Selection: removes all selected faces from the selection.
    • Tangency Propagation: includes all faces tangent to selected faces in the selection
    • Fillet Propagation: includes all tangent continuous filleted faces of the selected face in the selection.
      • Fillet propagation stops at sharp edges.
      • The fillet propagation cannot be performed on variable radius fillet.

  3. Click the Faces to keep field and select both faces as shown.
    The faces turn blue, indicating that they will not be removed.

  4. Check the Show all faces to remove option to preview all the faces adjacent to the purple face that will be removed.

  5. Click OK to confirm.
    All of the faces have been removed. The new feature identified as RemoveFace.XXX is added to the specification tree.

  • If the remove face feature fails at the time of creation, the faces causing the issue get highlighted in red and are labeled. An error message is displayed. In this case, you have following options:

    • Edit the feature to provide valid inputs

    • Click the labels of the error causing faces, to remove them from the Faces to remove box.

    • Deactivate the feature.

  • You can edit the deactivated feature to provide the valid input element.

 
 
If the operation takes longer than five seconds to complete, the Update in Progress dialog box appears. In this case, do one of the following:
  • Wait for the operation to complete.
  • Click Cancel to interrupt the operation.
You can change inputs in the Remove Face Definition dialog box, to restart the remove face operation.

 

Create a Remove Face Feature Using Limiting Elements
  You can partially remove some faces using limiting elements. This particularly helps you to locally modify a fillet.

  1. Click Remove Face again and select the face as shown to remove it, in the Remove Face Definition dialog box.

  2. Click More>> to define limiting elements for the removal of the face.
    The Remove Face Definition dialog box dialog box is expanded:

  3. Right-click in the Faces to limit box and select Create to determine a face to limit.
    A new Faces to Limit dialog box appears.

     

  4. In the Faces to limit box, select the face (shown in blue color) and in the Limiting element box, select the plane as shown.


    The arrow indicates the side of the face to be removed.
     
    • You can click Reverse Direction or orange arrow to reverse the direction of the face to be removed.
    • The face to limit cannot be a removed face (Select the Show all faces to remove check box to see which faces are the removed faces).

  5. Click OK to confirm the first limiting element.
    The orange arrow remains available on the limiting element. Thus, you can change the orientation of the limiting element without editing it.

  6. Repeat step 3 to 5 to create another limiting face as shown.

      The Faces to limit box displays the following contextual commands:
    • Edit: edits the limiting face created.
    • Remove: deletes the selected face to limit.
    • Clear all: clears all the selections made.
    • In this command, you can select only one face to limit.
    • The face to limit can only be split once.

  7. Click OK to confirm the second limiting element.
    The face is partially removed up to the limiting elements depending on the defined direction. The new feature identified as RemoveFace.XXX is added to the tree.

 

More About Remove Face Features

Remove Face  does not create any new face. The capability is valid for existing topology extrapolation. This is why the following pink face cannot be removed.

However, this one can be removed because there is a possible trimming face that can be used by the application.

           
 

Self-Intersecting Volumes

The Remove Face capability may produce self-intersecting volumes as illustrated in the following example:

Initial geometry

The 3D shape is composed of a shelled pad. Two fillets (in lavender) were created on two of its edges.

Resulting remove face feature

Removing the internal fillet feature generates an inconsistent shape.
To analyze self-intersecting volumes, we recommend you use the Split capability which most of the time provides a better view of the problems:
 

Removing the appropriate face

By removing the external fillet first there is no self-intersecting volumes, the resulting geometry is satisfactory.