Manufacture of heat-shrink tubing

How is heat-shrink tubing manufactured?

Manufacture of heat-shrink tubing by BIT Bierther GmbH

The outstanding properties of BP heat-shrink tubing are the result of a meticulous manufacturing process, which can be broken down into the following steps:

• Material preparation: First, the materials required for the heat-shrink tubing are mixed. This usually comprises a base polymer, often from the polyolefin group, as well as various additives such as UV stabilisers, flame retardants, colourants and cross-linking accelerators. The exact composition of the material depends on the requirements of the application.
• Extrusion: Following material preparation, the material is fed into an extruder in the form of granules. The extruder is a machine that melts the material using heat and forces it through a die to form the desired tube. During the extrusion process, the molten material is continuously forced through the extruder, thereby taking on its tubular shape.
• Cross-linking: In order to achieve the desired shrinkability and other properties, the extruded tubing is subjected to cross-linking by irradiation with electrons. During cross-linking, the molecules of the plastic are bonded together. This cross-linking ensures that the heat-shrink tubing retains its shape-memory properties.
• Expansion: In the final stage of production – the expansion of the tubing – the BP heat-shrink tubing is continuously heated, without reaching its melting point, and stretched using compressed air. Through this process, the tubing takes on its intended, larger shape, which it retains until it is shrunk.