Design information for bending

Bending is a forming process used to create three-dimensional products from flat sheet metal. Various bending processes allow classically welded or bolted assemblies to be combined into a more cost-effective single part. In industry, bending has become established for both small and large parts.

Minimum leg length

The smallest possible leg length is a tool-related minimum dimension that must be observed in the part design. If a leg length is too short, the workpiece cannot be bent according to the design.

For a 90° bend, the width W can be used to determine the smallest leg length Smin:

Smin = √2/2 * W

The following table lists the respective guide values for a 90° bend. As the material thickness increases, the minimum leg length Smin changes as a result of the tools used.

Minimum distances to the bending edge

Workpieces that have a hole or a cut-out near the bending line in the uncoiled state must maintain a minimum distance Lmin. If the distance falls below Lmin, the cut-outs will be deformed during the bending process.

The minimum distance Lmin is calculated with the die width W as follows:

Lmin = 0.75 * W

A quick, workshop-friendly method for determining the minimum distance is to use the smallest leg length. Cut-outs and holes that have a distance to the bending line that is greater than the smallest leg length can be produced without deformations.

Z-bends

In the case of two successive bends, so-called Z-bends, a minimum step dimension Xmin must be maintained due to the bending tool used.

Bend reliefs

The run-out of the bending lines should not pass directly into the material, otherwise the compression and expansion at the bending zone will be impeded and cause cracks. Attached relief slots minimize the notch effect and thus ensure the desired bending result.

Sloping edges

Free bore for bending bead

For process reliability and to avoid unsightly corners when bending edges meet, a corner notch D should be provided at the intersection of the crossing bending lines. Corresponding minimum dimensions are listed in the following table depending on the material thickness.

Closed corners

The bending manufacturing process can only be used if the entire sheet metal part can be unwound.