Krauss-Maffei is offering production systems for plastic metal composite pipe up to 110 mm diameter.
The company has signed a cooperation agreement with THE Thomas Machines, Couvet (CH), to produce the machines and equipment for the aluminium or steel layer.
Composite pipe, made of plastic and metal, is increasingly preferred for applications from drinking water pipe, radiator connections, and underfloor heating to gas and fuel supply lines. The advantages of using composite pipe is that it easy to install, has low weight, high corrosion resistance, high stiffness and good sound damping. These benefits are helping plastic metal composite pipe to penetrate the market, with annual sales growth in the region of 10 percent.
The inner pipe layer is usually cross-linked PE (PE-X), or PP-R or PE-HD for some applications. The outside of the extruded inner pipe is coated with adhesion promoter. The metal layer is shaped around the inner pipe and the longitudinal seam is continuously welded. Apart from aluminium, steel is an increasingly popular option for the outer layer. The metal layer acts as a diffusion barrier and reduces the thermal longitudinal expansion of the pipe. In the final step, an adhesion promoter and the 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). There are obvious advantages to having both welding processes available in the same shaping and welding machine, where it is possible to switch from one to the other as required. The LATIG unit offered by Krauss-Maffei and THE incorporates all components required for both processes. The welding heads are switched automatically. The availability of alternative methods in one and the same unit reduces manufacturing costs and increases the flexibility of the production line.
As a supplier to the former Swisscab SA (CH), THE Thomas Machines worked intensively on the development of many new processes. After the Swisscab bankruptcy in 2002, some company employees with extensive development experience in composite pipe joined THE. In the past two years, this influx of know-how has helped THE to optimize the original Swisscab technology and test the new solutions successfully in customer installations. The developments were protected with an impressive array of patents.
The cooperation between Krauss-Maffei and THE unites the extensive and complementary know-how of the two companies. The cooperation has produced a wide portfolio of machine variants capable of meeting every imaginable customer requirement.
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