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Design Considerations

The bend radius should be kept the same for all radii in the part to minimize set up changes. Bend radius guidelines are as follows:

  • For most materials, the minimum inner radius should be at least 1 material thickness.
  • As a general rule, bending perpendicular to the rolling direction is easier than bending parallel to the rolling direction. Bending parallel to the rolling direction can often lead to fracture in hard materials, thus bending parallel to rolling direction is not recommended for cold rolled steel > Rb 70, and no bending is acceptable for cold rolled steel > Rb 85. Hot rolled steel can be bent parallel to the rolling direction.
  • The minimum flange width should be at least 4 times the stock thickness plus the bending radius. Violating this rule could cause distortions in the part or damage to tooling or operator due to slippage.

  • Slots or holes too close to the bend can cause distortion of these holes. Holes or slots should be located a minimum of 3 times the stock thickness plus the bend radius. If it is necessary to have holes closer, then the hole or slot should de extended beyond the bend line.
  • Dimensioning of the part should take into account the stack up of dimensions that can happen and mounting holes that can be made oblong should be.
  • Parts should be inspected in a restrained position, so that the natural flexure of the parts does not affect measurements. Similarly, inside dimensions in an inside bend should be measured close to the bend.