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Designing for Manufacture in Sheetmetal


In this Tip & Trick are some simple guidelines for designing sheetmetal parts which are both accurate and cost-effective to produce.


General Tips

  • Use consistent bend radii for all bends per part where possible – it helps minimise setup changes.
  • Use standard vee-dies for press brake forming
  • Dimension from a feature to an edge. Avoid feature-to-feature dimensions over two more planes.
  • Dimension to outside dimensions, unless with inside dimension is critical.
  • As a minimum, inside bend radius should be equal to the material thickness. For highly loaded parts use 2-3x the thickness depending on the material.

Minimum Hole-to-Bend Distance

When a bend is too close to a hole, the hole may become deformed and oval-shaped. Use the figures shown to avoid the extra cost of cleaning up holes after bending.holes

Minimum Flange Widths

To determine the minimum flange width, use the following formula. This width can be less but will require secondary operations and is far more costly.
A good rule of thumb if size isn’t an issue is 4xT. This will help minimise issues with v-blocks etc.

Stretch Flanges

widthstretch

Edge Distortion

For thicker materials, edge distortion at the bend can become an issue. In situations where an overhang is unacceptable, add bend relief as shown.Edge1

Design to Reduce Spring Back

Spring back occurs due to the changing stress pattern across the bend, and the material tends to return to its original shape.

Bottoming or coining can help alleviate these issues, however changing the geometry across the bend can also help.

springback
One example which will reduce the amount of spring back is: Adding a bead across the bend, as shown opposite.bead2
If you would like to find out more about our design services, see our Sheet Metal Modelling brochure here or check out our full range of services.
References:
Quality Tool Sheet Metal Design Handbook
Sheet Metal Guidelines

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