Roll Bending

Roll bending forms long tubes, pipes, and sections into large, smooth curves or rings using multiple rollers, ideal for big radii and structural profiles.

Overview

Roll bending, also called section rolling, uses a set of powered rollers to gradually curve tube, pipe, and structural sections into large, smooth arcs or complete rings. The process excels at long parts, big bend radii, and heavy sections that are impractical to form with fixed-radius dies. It handles square and rectangular tube, angle, channel, beam, and pipe with relatively low tooling cost.

You should consider roll bending for architectural curves, circular frames, coils, and structural elements where a consistent, sweeping radius matters more than tight tolerance at each bend. Expect moderate dimensional accuracy and some cross-section distortion, especially on thin-walled or asymmetric profiles. Roll bending is efficient for low to high volumes once roller setups are dialed in, but it is not the right choice for sharp bends, tight radii near the minimum bend limit, or parts requiring very precise bend locations and profiles.

Common Materials

  • Carbon steel tube
  • Stainless steel tube
  • Aluminum 6061
  • Aluminum 5083
  • Copper tube
  • Structural steel sections

Tolerances

±0.060" on bend radius and chord length under typical job-shop conditions

Applications

  • Architectural curved tube and pipe railings
  • Structural rings and rolled beams for buildings
  • Tank and silo rings or shells
  • Large pipe coils and serpentines
  • Curved frames for canopies and façades
  • Rings and flanges from flat bar or sections

When to Choose Roll Bending

Choose roll bending for long tubes, pipes, or sections that need large, smooth curves or complete rings with reasonable, not ultra-tight, tolerances. It fits architectural work, structural members, and coils where tooling cost must stay low and the same radius repeats over long lengths. It is best when the bend radius is several times the section size and you can accept some ovality or deformation.

vs Mandrel Bending

Pick roll bending over mandrel bending when you need large-radius curves or full rings in longer parts and can accept some cross-section ovality. Mandrel bending is overkill for big, gentle sweeps where internal support of the tube isn’t critical and you want lower tooling cost.

vs Rotary Draw Bending

Use roll bending instead of rotary draw bending when the bend radius is very large relative to the tube size or the part is too long for standard draw-bend tooling. Roll bending lets you form continuous arcs and rings without multiple discrete bends or expensive, large-radius draw dies.

vs Compression Bending

Choose roll bending over compression bending when you need smooth, continuous curves over long lengths rather than one or two localized bends. Roll bending also handles heavier sections and structural profiles that are difficult to clamp and bend cleanly in a compression setup.

vs CNC Tube Bending

Select roll bending instead of CNC tube bending when the geometry is essentially a constant large-radius arc or ring and high positional accuracy between multiple bends is not required. Roll bending reduces tooling and programming cost for simple swept curves, especially on large or heavy profiles.

vs Stretch Forming

Use roll bending instead of stretch forming when you want lower tooling cost and don’t need aerospace-level contour precision or surface quality. Roll bending is more economical for general structural and architectural curves where some springback and radius variation are acceptable.

Design Considerations

  • Specify realistic bend radii several times the section depth; very tight radii in roll bending increase distortion and setup time dramatically
  • Allow generous tolerances on bend radius and chord length, and state what features are critical so the shop can fixture and measure appropriately
  • Provide extra straight length at both ends for gripping and setup, with allowance for trimming off any distorted regions after rolling
  • Clearly define orientation of asymmetric sections (angle, channel, I-beams) relative to the bend plane to avoid incorrect rolling direction
  • Avoid abrupt cross-section changes, holes, or welds near the bend zone, or clearly call them out so the shop can plan tooling and sequence
  • Include desired final shape definition (target radius, chord, and rise or template) in the RFQ so the shop can evaluate feasibility and inspection method