Compression Bending

Compression bending forms tubes by pushing them around a fixed die without internal support, enabling simple bends quickly but risking ovality and wrinkling.

Overview

Compression bending (crush bending) forms tube by clamping it against a bend die and forcing it around the die with a pressure shoe—typically without a mandrel or wiper. Tooling is simple and cycle times are fast, making it a cost-effective choice for basic 1-plane bends and moderate cosmetic requirements.

Expect more cross-section distortion than mandrel-based methods: ovality, wall thinning on the outside radius, and wrinkling on the inside radius increase as the bend gets tighter and the tube gets thinner. Bend angle accuracy is often limited by springback and material variation, and tight bend radii can be inconsistent. It works best on thicker-wall tube, larger radii, and parts where minor flattening is acceptable or can be hidden/managed in assembly.

Common Materials

  • Mild steel
  • Stainless steel 304
  • Aluminum 6061
  • Copper
  • Brass

Tolerances

±0.030"

Applications

  • Handrails and guardrails
  • Furniture frames
  • Automotive seat frames
  • Appliance tubing brackets
  • General-purpose tubular supports

When to Choose Compression Bending

Compression bending fits prototypes to mid-volume runs needing straightforward bends with low tooling complexity and fast throughput. It’s a good match for thicker-wall tube and larger bend radii where some ovality or minor surface marking is acceptable. Choose it when cost and speed matter more than perfect roundness and tight angle/position control.

vs Mandrel Bending

Choose compression bending when you can tolerate more ovality and inside-radius wrinkling and you want lower tooling cost and quicker setup. It’s a practical option for thicker-wall tube and larger radii where maintaining full ID/OD roundness isn’t critical.

vs Rotary Draw Bending

Choose compression bending for simpler parts where bend precision and repeatability requirements are moderate and you want faster, less expensive tooling. For non-critical fit-up and cosmetics, it can meet needs without the tighter process control rotary draw typically targets.

vs Roll Bending

Choose compression bending when you need a defined bend location and angle rather than a long, sweeping radius. It’s better suited to discrete bends near features, cut lengths, or end forms where roll bending’s gradual curvature isn’t desired.

vs CNC Tube Bending

Choose compression bending when the part is simple enough that dedicated tooling and a basic bend station are the fastest path to parts. It can be more economical for short programs and single-plane bends where advanced multi-axis control and high repeatability aren’t required.

vs Stretch Forming

Choose compression bending when you don’t need large-radius bends with controlled springback and surface finish. It’s typically smaller footprint and lower cost for compact bends and general fabrication work.

Design Considerations

  • Keep bend radii generous; tight CLR on thin-wall tube drives wrinkling and excessive ovality
  • Specify acceptable ovality/flattening limits and whether minor die/shoe marks are allowed
  • Provide straight lengths before and after the bend for clamping and reliable location control
  • Avoid placing holes, slots, threads, or end forms too close to the bend tangent points
  • Call out tube OD, wall thickness, and temper/condition; small material changes significantly affect springback and quality
  • If the tube must pass a component or maintain flow area, design with extra clearance or allow secondary sizing/straightening