ROLL FORMING DESIGN CONSIDERATIONS Symmetry Try to incorporate as much symmetry in profile designs as possible. This will minimize twist. Leg length Keep the flat portion of legs at least 3 times material thickness to allow for proper forming. avoid use Ribs for flatness Avoid large flat areas which are subject to waviness. Incorporate ribs for flatness and stiffness. avoid use Short parts Very short parts can slow down a line or require secondary cutting. Holes Holes should be repetitive if possible to allow efficient pre-punching. Holes and notches Holes and notches close to or on a bend line will be subject to distortion if pre-punched. Keep at least 3 x material thickness distance away. Holes and notches Holes and notches should be at least 3 times material thickness from part edges to avoid breakout. Deep parts Deep parts require larger rolls and larger machines all which add to cost. Design shallower parts when possible. Minimum bend radii Minimum bend radii vary with material specifications. 1 times material thickness is the minimum for mild steel. Avoid narrow slots Avoid narrow slots which require narrow rolls and are subject to breakage. avoid use Avoid wide, sweeping radii. Avoid wide, sweeping radii. Use sharper bends which form beyond the elastic limit of the material and cause a permanent set. avoid use Blind corners Blind corners should be avoided if possible. avoid use Tolerances Tolerances should be no more restrictive than necessary. Tighter tolerances add to tool and part cost. Simplify parts Simplify parts as much as possible. Complex parts require more tooling passes which increases cost. ©Holland Binkley