Practical design for manufacturability guide for bent sheet metal parts. Learn about flange lengths, bend relief, hole placement, and features that simplify bending.
Introduction
Good design is the foundation of manufacturable bent parts. At Fulei Metal, we review hundreds of designs and help optimize them for bending.
Flange Design
Minimum Flange Length
Minimum: 4 times material thickness, or at least enough for back gauge and operator holding. Too-short flanges cannot be bent reliably.
Maximum Flange Length
Limited by machine throat depth and part handling capability. For very long flanges, consider alternative designs.
Bend Relief
Add relief at bend lines near cut edges: width at least 1 thickness, depth at least 1 thickness beyond bend. Prevents tearing and distortion.
Corner Relief
For boxes and enclosures: notch relief prevents overlap. Slot relief allows both flanges to bend. Design appropriate relief for the corner type.
Hole Placement Near Bends
Holes should be at least 2 times thickness plus bend radius from the bend center. Holes too close to bends deform during bending. Slots are more forgiving than round holes.
Bend Direction
Bend across grain for tight radii. If grain direction is unknown, specify across-grain bending. Consider nesting implications.
Consistent Bend Radii
Use the same radius for all bends on a part. This reduces tool changes and setup time. Standard radii: 0.5, 0.8, 1.0, 1.5, 2.0, 2.5, 3.0 mm.
Bend Direction Consistency
Design parts so bends are in the same direction where possible. This reduces part reorientations. Up-bends and down-bends require flipping.
Avoid Impossible Geometries
Ensure all bends can be made without tool interference. Verify with 3D simulation. Consider the tool access for each bend. Avoid bends that require impossibly narrow punches.
Tolerancing
Bend angle: plus or minus 0.5-1.0 degrees. Flange length: plus or minus 0.2-0.5 mm. Avoid over-tolerancing non-critical dimensions.
Assembly Considerations
Consider how bent parts fit with mating components. Design for assembly access. Account for tolerance accumulation. Provide adjustment features where needed.
Conclusion
Designing for bending avoids manufacturing problems and reduces cost. At Fulei Metal, our design review services help clients create parts that are easier to bend, higher quality, and more cost-effective.