A tube bending machine bends tubes and pipes to set angles and radii without flattening or kinking them. Rotary draw benders pull the tube round a bend die; a mandrel inside the tube supports the wall on tight bends. CNC benders bend in three axes so complex parts like exhaust pipes and frames come out in one setup.
Quick facts
- Main types
- Rotary draw (with or without mandrel), roll bender, compression / ram bender
- Capacity
- From about 6 mm (0.236 inch) tube to 150 mm (5.91 inch) pipe and more
- Bend radius
- Down to about 1–1.5 × tube diameter with a mandrel
- Control
- Manual, NC (angle only), CNC (length, rotation and angle)
- Tooling
- Bend die, clamp die, pressure die, wiper die, mandrel for each size
- Used for
- Frames, furniture, exhausts, hydraulic lines, handrails
Types and what they suit
| Type | Suits |
|---|---|
| Rotary draw with mandrel | Tight bends in thin-wall tube, exhausts, furniture |
| Rotary draw without mandrel | Thick-wall pipe, larger radii |
| Roll (three-roll) bender | Large-radius curves, arches, coils |
| Ram / compression bender | Simple bends in pipe where some flattening is fine |
Main parts
- Bend die that sets the bend radius
- Clamp die that grips the tube against the bend die
- Pressure die that follows the tube along the bend
- Wiper die and mandrel that stop wrinkles and flattening on tight bends
- Carriage that feeds and rotates the tube between bends (CNC)
Good to know
- Each tube size and radius needs its own tooling set
- Thin walls and tight radii need a mandrel and wiper die
- Springback means the machine bends slightly past the angle
- Leave a straight length between bends for the clamp die
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Questions
- What is a mandrel in tube bending?
- A rod or a chain of balls placed inside the tube at the bend. It supports the wall so the tube does not flatten or wrinkle on tight bends.
- What is the smallest bend radius for a tube?
- With a mandrel and good tooling, about 1–1.5 times the tube outside diameter; without a mandrel, usually about 3 times or more, depending on wall thickness.
- What is the difference between a tube and a pipe for bending?
- Tubes are sized by outside diameter and wall thickness and are usually thinner; pipes are sized by nominal bore and schedule. Both bend on the same machines with matching tooling.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 18 October 2026.