Unfolding Surfaces

This task shows you how to unfold a surface as another surface or a trim line.
Open Unfold01.CATPart from the samples directory.

  1. Click Unfold in the Process Part Separation  toolbar.

  2. Select an axis system (stamping direction).
    The unfold orientation and angle are computed from the Z-Axis.
    The mean line or the folding line from axis is projected on its XY plane.
    The XY plane is used to compute a support surface, when none is selected.

  3. Select the Surface to Unfold.

  4. Select a Fixed Area.
    It is a surface or 3D curve that intersects the surface to unfold.
    The actual fixed area is specified by all the edges of the surface
    to unfold that lie entirely on the fixed area.
    These edges form the folding line.

  5. Optional: Go to the Settings tab and select a Support Surface.
    The unfold is projected
    • On the support surface, if selected
    • On an extrude of the folding line in the reference XY plane otherwise.

  6. Select the type of unfold to create:
    • Unfold as Planar Surface: Unfolds the selected surface as a planar surface, possiblbly on a support.
    • Unfold as Trim Line: Unfolds the selected surface as a trim line, possibly on a support.
    • Partial Unfold: Unfolds the selected surface by keeping the inital geometry and recomputing a fillet.

  7. Still in the Settings tab, set parameters as necessary:
    • Angle between the unfolded surface and the Z-Direction of the selected axis system.
    • Reverse direction
    • Computation options for the folding line:
      • Mean Line: The folding line is a line computed between the first and the last points of the folding line.
      • Mean Line From Axis: The folding line is the computed mean line projected on the reference XY plane.
      • Folding Line: The folding line is the intersection between the fixed area and the surface to unfold.
      • Folding Line From Axis: The folding line is the intersection between the fixed area and the surface to unfold,
        projected on the reference XY plane.
    • Fillet Computation Options:
      • No Fillet. This option is not available when unfolding as spec.
      • Automatic Fillet: Computes the fillet radius automatically from the bend angle
        • with the specified maximum chord where the angle between the tangent
          of the surface to unfold and the Z-Direction is minimum
        • with the minimum chord where the angle is maximum.
          In this case, the radius for the other angles is computed by a linear interpolation.
      • Manual Fillet: Defines the fillet using local radiuses on the folding line.
        A list of default local radii computed from the current automatic options is proposed.
        Select a radius in the list or in the graphic area and modify its value in the dialog box.
        Alternatively, pick a vertex, select Add Target Radius   from the contextual toolbar and enter its value.
        Drag a local radius to move it.
      • Minimum Fillet Chord
      • Maximum Fillet Chord
      • Master Fillet Profile: The master fillet profile is the one used to compute the rotation of the surface.
        It is the only fillet profile kept as is.
        Other target fillet profiles are replaced by splines, that reach the rotated surface.
        If you do not select a master fillet profile, the target fillet radius closest to the mean radius is used.
    • Sheet Metal Properties:
      • Thickness
      • KFactor: Ratio of the neutral axis to the material thickness.
      • Automatic KFactor. Select this check box to compute the KFactor dynamically.
    • Faces to ignore: The selected faces are considered as a plugged holes when computing the unfold.

  8. Click OK.
    The unfold is created under an Unfold Set.
    Initial model

    Result as Planar Surface


    As Partial Unfold


    As Trim Line