Roll Bending

Roll bending (plate rolling) forms sheet and plate into smooth, consistent curves or cylinders using rotating rolls, ideal for large radii and tubular shells.

Overview

Roll bending, or plate rolling, forms sheet and plate into arcs, cones, and cylinders by passing the material through powered rolls. It excels at producing smooth, continuous curvature on medium to large parts, from thin sheet to heavy plate. Typical applications include tanks, pressure vessel shells, ductwork, and structural arches.

Choose roll bending when you need consistent radii, full cylinders, or long curved sections without the faceting you get from multiple discrete bends. It works well for low to medium volumes and is efficient for large parts that would be difficult or impossible to form in a press brake. Tradeoffs include looser tolerances than precision bending, setup sensitivity to material springback, and limitations forming tight radii or complex, localized features in the same operation.

Engineers should allow realistic bend radii, account for weld seams in rolled cylinders, and expect some trial to dial in exact curvature on new materials or thicknesses. Clear specifications for inside radius, seam gap, and acceptable out-of-round help shops quote and deliver predictable results.

Common Materials

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

Tolerances

±0.02" on diameter and width, ±1° on bend angle for typical shop plate rolling

Applications

  • Tank and pressure vessel shells
  • Cylindrical ductwork and chimneys
  • Truck and rail tanker barrels
  • Structural and architectural arches
  • Rolled shells for drums and housings
  • Cones and transition sections

When to Choose Roll Bending

Specify roll bending when you need long, smooth curves or full cylinders in sheet or plate, especially for medium to large diameters. It suits low to medium production where part length, diameter, or thickness makes press braking impractical. Use it for shells and arcs that will be welded, flanged, or machined after forming.

vs Press Brake Bending

Choose roll bending when you need smooth, continuous curvature or full cylinders instead of segmented, faceted bends. It handles longer parts and larger diameters more efficiently, especially for tanks, shells, and large arches where multiple brake hits would be slow, hard to align, and leave visible bend lines.

vs Hemming

Pick roll bending when you are forming global curvature into a part, not just folding over an edge. Hemming is for stiffening and safe edges on relatively flat parts; roll bending is for defining the overall cylindrical or curved shape of the part, often prior to welding and final finishing.

vs Stamping

Use roll bending for larger, lower-volume curved parts where dedicated stamping dies are not economical. Stamping can form curves and features in one hit but needs high tooling investment and presses sized to the blank; roll bending relies on adjustable rolls and is far more flexible for different diameters and lengths.

vs Stretch Forming

Select roll bending for standard cylindrical or conical shapes where you do not need highly precise, compound contours. Stretch forming offers tighter control and complex curves but requires dedicated tooling and higher setup costs, while roll bending adjusts quickly for different radii along straight lengths.

vs CNC Machining

Choose roll bending instead of machining when the part is fundamentally a thin-walled shell or large cylinder. Machining a curved shell from solid is slow and wasteful; rolling plate to shape and then welding or lightly machining critical interfaces is far more cost-effective for tanks, housings, and ductwork.

Design Considerations

  • Specify inside radius, target diameter, and allowable out-of-round or ovality so the shop can choose suitable roll settings and passes
  • Avoid very tight radii; as a rule of thumb, keep minimum inside radius at least 1–3 times material thickness unless you confirm capability with the shop
  • Call out weld seam location and required straight sections at ends to allow clamping, trimming, and welding after rolling
  • Account for springback by agreeing on functional measurements (finished diameter or chord height) rather than relying only on nominal roll settings
  • Keep thickness and material spec realistic for available roll capacity; very thick, high-strength plate may require multiple passes or larger machines
  • Provide flat patterns with developed lengths and edge prep details so the shop can cut, roll, and weld with minimal rework