March 4, 2015

Posted on March 4th by Dave Breiner, Synergis Manufacturing Solutions Engineer
What can you expect from a sheet metal bend corner? How will it look and how can you adjust them? Today I will give you some examples of bend corners and how they appear in the flat pattern and the folded model.Sheet Metal 1
I will begin by addressing how to change the GAP between 2 Flanges. The Material I am using is Stainless Steel 11GA which generally measures .125 inches thick. The default setting in our Rule set the Gap at the thickness of the material.Sheet Metal 2
Sheet Metal 3If you would like to close this Gap to aid in welding, you only need to enter a distance under the Seam Gap spacing. In this case, I will enter .01 inches.Sheet Metal 4
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There are several options under the corner tab for 2 and 3 bend intersections. I will review a few from each and show the results.

2 Bend Transition

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Round – A corner relief defined by a circular cutout in the flat at left. The cutout has a center placed on the intersection of the bend lines. Below are two views of the folded corner.Sheet Metal 7
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Square – A relief shape with a square cutout and centered on the bend line intersection of the two bend lines. Sheet Metal 10
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Tear – A relief shape defined in flat by extending the flange edges to their intersection. Named due to material failure caused by tearing across the bend zone in the folded model.
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Corner Relief Size

For a 2 bend intersection such as a Square or Round. When any two flanges or Contour Flanges meet at a 2 Bend corner, a parameter called CornerReliefSize is applied. This parameter sets the space between the Flanges. CornerReliefSize is defined by the Sheet Metal Rule, of which the default setting is 4 X the Thickness at below first. 2 X the Thickness is shown after.
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3 Bend Intersection

Use this option to define the Default corner relief to display in the flat pattern when 3 bends intersect.
Note: The folded model does not display the selected relief option.
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No Replacement As indicated, no replacement of the “as modeled” geometry is made in the flat pattern.
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Intersection A corner relief shape defined in the flat by extending and intersecting the flange edges.
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Full Round A corner relief shape defined in the flat by extending the flange edges to their intersection and then placing a fillet tangent to the bend zone tangency lines. Radius will likely be larger than what would be produced using the Round with Radius option.
Sheet Metal 20Round with Radius A corner relief shape defined in the flat by extending the flange edges to their intersection, and then placing a tangent fillet of the size specified. Radius will likely be smaller than what would be produced by the Full Round option. When using the Round with Radius relief shape a size field is available. By default is set to the thickness.
You may need a little trial and error to achieve the corner bend you are looking for but there are a lot of choices to aid in your decision making. I hope you found this article informative and helpful.
Till next time!