What is a tube end forming machine?
A tube end forming machine plastically reshapes the end of a pipe. The best known operation is expanding: widening the end so that a second pipe of the same size slides inside it.
That removes the need for a separate coupling. Two pipes of identical diameter fit together and are then soldered, pressed, welded or clamped.
The common operations
- Expanding (swaging out) — the end is widened until its internal diameter matches the outside diameter of the adjoining pipe.
- Reducing — the end is narrowed so it fits inside a larger pipe.
- Flanging / collaring — the rim is turned outwards into a collar that a loose flange or a sealing ring can bear on.
- Flaring — a conical widening, familiar from compression joints in copper pipework.
- Grooving — rolling a circumferential groove for an O-ring or a grooved coupling.
A production machine often has these as separate stations, so one pipe passes through several operations in a single set-up.
Where it is used
In building services and in steel and stainless steel fabrication: pipework for heating, cooling, ventilation and process installations, but also furniture and handrail tube. For copper and thin-wall material there are hand tools — expander sets and expanding pliers — that apply the same principle on site.
Points to watch
- Wall thickness. Expanding stretches the material and thins it. An over-expanded end is weaker and can split; stay within the maximum expansion the machine builder states.
- Material. Hard-drawn tube often has to be annealed first. Stainless steel springs back and needs more over-travel.
- Roundness and burrs. Cut square, deburr inside and out, and round the tube before forming — otherwise the formed end goes oval and the joint leaks.
- Permitted use. Not every self-made joint is acceptable for drinking water or gas. Follow the system the manufacturer has approved.
Related terms
- Pipe expanding
- Pipework
- Copper pipe
- Press fitting
- Building services
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