Shaping and welding

Co-developed with Swiss based THE Thomas Machines, Krauss-Maffei’s new Latig machine can produce plastic metal composite pipe up to 110 mm in diameter.

In the manufacture of composite pipe, the outside of an extruded inner pipe – usually manufactured from cross-linked PE (PE-X), or PP-R or PE-HD – is first coated with an adhesion promoter.

The metal layer layer – steel, or aluminium – is then shaped around the inner pipe and a longitudinal seam is continuously welded, acting as a diffusion barrier and reducing the thermal longitudinal expansion of the pipe.

In the final step of the process, an adhesion promoter and an outer plastic layer are applied together over the metal layer in a one-step process using a two-layer transverse spray head.

There are two processes which can be used for the longitudinal weld: laser welding and inert gas welding with a wolfram electrode (TIG welding). Having recognised that there are advantages to having both welding processes, the shaping and welding machine offered by Krauss-Maffei and THE Thomas Machines can handle both processes, automatically switching between the welding heads.

The availability of alternative methods in the same unit reduces manufacturing costs and increases the flexibility of the production line.

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