Roll Bending

Roll bending (plate rolling) forms sheet or plate into large-radius cylinders, cones, or arcs using rollers, optimized for long curved profiles and repeatable radii.

Overview

Roll bending (plate rolling) forms sheet or plate by feeding it through two- or three-roll machines to create arcs, cylinders, or cones. It’s best for long, continuous curves and large radii where a smooth profile matters more than sharp bend lines. Shops can pre-bend ends, roll to a target radius, and deliver parts as open arcs or as welded cylinders.

Choose roll bending for tanks, shells, ducts, rings, and curved panels in low to medium volumes, especially when the part length is long and the radius is consistent. Cost is driven by material thickness, width, radius tightness, and setup time for dialing in springback.

Tradeoffs: radius accuracy depends on material variability and springback; expect iteration and verification. Tight radii relative to thickness may be impossible or cause wrinkling/flat spots. Ends often have a short unrolled “flat” unless pre-bent, and true circularity typically requires a seam weld and post-weld truing.

Common Materials

  • Mild steel
  • Stainless steel 304
  • Stainless steel 316
  • Aluminum 5052
  • Aluminum 6061
  • A36 plate

Tolerances

±0.030" on radius/diameter (typical, varies with size/thickness)

Applications

  • Rolled cylinder shells for tanks and vessels
  • Conical transitions for hoppers and reducers
  • Large-radius architectural cladding panels
  • Rolled rings and bands for structural assemblies
  • Duct and stack sections for HVAC/industrial exhaust
  • Pipe saddles and curved stiffeners

When to Choose Roll Bending

Pick roll bending when the defining feature is a long, smooth constant radius (or cone) in sheet or plate. It fits prototypes through medium production where setup can be reused and parts are verified against a target radius/diameter. It’s most efficient when the rolled feature runs the full length of the part and doesn’t require crisp bend lines.

vs Press Brake Bending

Choose roll bending when you need a continuous curve (large radius) instead of discrete straight segments between bend lines. It produces smoother arcs on long parts and avoids multi-hit “polygon” faceting. It’s a better fit when the radius is the primary feature and repeatability matters across many parts.

vs Hemming

Choose roll bending when the goal is forming the overall part curvature, not closing an edge for safety, stiffness, or cosmetics. Hemming addresses edge treatment and typically relies on a prior bend; it won’t create a large-radius cylindrical or conical form. Roll bending can be combined with hemming later if you also need a safe finished edge.

vs Slip Rolling (Section/Roll Forming for Profiles)

Choose roll bending when you’re rolling sheet/plate into shells, arcs, or cones rather than bending extrusions, angles, or tubes with section rollers. Plate rolling uses different tooling and supports wider material with controlled radii over large areas. It’s the right choice when surface continuity and large diameter control dominate the requirements.

vs Stretch Forming

Choose roll bending when the part can be formed primarily by curvature without needing the material stretched tightly over a form block. Roll bending typically has lower tooling cost and faster setup for standard radii and cylinders. Stretch forming is better when you need highly controlled, compound curvature with minimal springback variation.

Design Considerations

  • Call out inside or neutral-axis radius/diameter and the measurement method (ID/OD/centerline), plus the allowed ovality if the part is a cylinder
  • Avoid specifying very tight radii relative to thickness; provide minimum radius guidance or accept a larger radius to prevent wrinkling and flat spots
  • Account for end effects: specify allowable unrolled flat length at the ends or require pre-bending if full-length curvature is critical
  • If the part will be a closed cylinder, define seam location/orientation and whether welding, grinding, or post-weld truing is required
  • Provide material spec and grain direction when relevant; springback and achievable radius shift with alloy, temper, and thickness tolerance
  • Include blank size assumptions or request the shop to develop the blank; trimming after rolling is common for accurate length and fit-up