Tube Forming

Tube forming reshapes metal tube into controlled profiles or expanded sections using dies and pressure, enabling lightweight, high-strength hollow parts with minimal joints.

Overview

Tube forming reshapes round or pre-shaped tube into a new cross-section or localized features (expansions, reductions, beads, flares) using dies, mechanical force, and sometimes internal pressure (hydroforming). It keeps the part hollow while creating geometry that would otherwise require welded assemblies.

Choose tube forming when you need high stiffness-to-weight, smooth load paths, and repeatable geometry in medium to high volumes. It’s common for structural members, fluid-carrying parts, and crash/impact structures where seams and brackets add cost, weight, and failure risk.

Tradeoffs: tooling is the big driver—die cost and lead time can outweigh savings at low volume. Geometry is limited by formability, wrinkling, thinning, and springback, so material selection and bend/feature radii matter. Dimensional control is good along formed features, but end conditions and secondary ops (piercing, trimming, welding, finishing) often define the final tolerance stack.

Common Materials

  • Low-carbon steel
  • Stainless steel 304
  • Stainless steel 316
  • Aluminum 6061
  • Aluminum 5052
  • Copper

Tolerances

±0.010"

Applications

  • Automotive hydroformed frame rails
  • Motorcycle and bicycle frame members
  • Exhaust and intake tubing with end forms
  • Roll cage and chassis tubes with beads/expansions
  • Heat exchanger and fluid manifold tubes
  • Furniture and equipment tubular frames

When to Choose Tube Forming

Tube forming fits parts that need a hollow structure with shaped sections, localized features, or transitions that must be strong and repeatable. It makes sense when you can amortize tooling across production volume or when eliminating weldments offsets tooling cost. It’s a strong choice for weight-sensitive designs where stiffness and fatigue life matter.

vs Tube Cutting

Choose tube forming when you need geometry beyond straight cut-to-length—expanded ends, beads, swages, or section changes that add stiffness or provide assembly features. Cutting is typically a prep step; forming creates functional features that reduce added brackets, inserts, or welds.

vs Tube Bending

Choose tube forming when the primary requirement is changing cross-section or adding local features rather than just changing the tube path. Bending controls centerline shape, but it won’t create expansions, complex section transitions, or die-defined profiles the way forming (including hydroforming) can.

vs Sheet Metal Forming

Choose tube forming when you need a closed-section part with high torsional stiffness and fewer seams. Sheet forming often requires hemming or welding to close the section; tube forming keeps a continuous tube wall and can consolidate multiple stampings into one part.

vs CNC Machining

Choose tube forming when the geometry can be die-formed and production volume favors cycle time over per-part material removal. Machining is flexible for low volume and tight feature tolerances, but it’s usually inefficient for long hollow structures and can’t match formed strength from continuous grain flow.

Design Considerations

  • Specify starting tube OD/ID and wall thickness with realistic tolerances; formed results depend heavily on incoming tube variation
  • Use generous radii and gradual transitions to reduce thinning, splitting, and wrinkling in expansions and section changes
  • Define which datums matter (end faces, holes, formed features) and allow secondary trim/pierce operations to set critical locations
  • Avoid tight feature spacing near tube ends unless you plan for dedicated end-support tooling or post-forming machining
  • Call out allowable ovality, thinning, and surface marks if they matter; cosmetic and sealing requirements drive process choices
  • Provide expected annual volume and material condition (annealed/T6, welded vs seamless) so shops can choose tooling and forming method accurately