Tubes can be manufactured from Desmopan® or Texin™ either horizontally or vertically. The horizontal arrangement is usually selected where the pipes/tubes cannot be deflected around corners because of their hardness and size.
Vertical manufacture is recommended for the production of thin-walled tubular film that is wound up flat.
To ensure that the bubbles do not collapse on leaving the die and that no dimensional fluctuations occur, a constant supply of calibrating air must be passed through the die to inflate the tube and keep it in shape.
Fig. 1 shows a tube extrusion line.
Fig. 1: Tube extrusion line
When extruding thinwalled tubing, it is an advantage to pre-cool it intensively with air. The flow of air solidifies the surface so that the subsequent water cooling cannot make any marks on the tube (Fig. 2).
For the take-off unit, conveyor belts or rubbercovered caterpillar take-off units give good results.
Fig. 2: Pre-cooling with air