Designing parts that bend well
Bend radius, flange length, hole spacing and reliefs: five simple rules for bent parts that come out right the first time.
How bending works.
A press brake pushes a flat part into a V-shaped die to fold it. The tooling needs some room to grip the metal, and the metal stretches on the outside of the bend. Design with that in mind and your part comes out exactly as drawn.
Five rules of thumb.
- Flanges long enough to grip: make each bent leg at least about 4× the metal thickness. Shorter legs slip in the tooling.
- Inside bend radius about equal to the thickness: tighter bends can crack the outside, especially in aluminum 6061.
- Keep holes away from bends: about 2.5× the thickness plus the bend radius, or they stretch into ovals.
- Add bend reliefs: where a bend ends inside the part, cut a small notch at least as wide as the thickness so the corner doesn't tear.
- Same direction is cheaper: bends that all go the same way, with the same radius, mean fewer tool changes.
These are starting points. The shop's tooling sets the real limits, and our size check uses them when you order.
Drawing your bends.
- Draw the part flat, with bend lines on their own layer, and give each bend's angle and direction (up or down).
- Dimension to the outside of the bends unless you say otherwise.
- Not sure how to flatten a 3D part? Send the 3D model or a sketch and order the CAD service: we draw it for you.
Not sure your design works? Upload it. Our size check flags anything too small or too close before you pay, and a person looks at every custom job.
Keep reading.
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