2. Stages of a standard tube line

2.1 Raw material dosing systems

The raw material is fed into a hopper above the extruder.

When mixtures are made, either volumetric or weight (or mass) dosing systems are used, on the total mixture or on each component. Each component has its own hopper (figure 7 ), before the material is sent to the area where the various components are added together (often in the extruder feed column). This zone may be a mixing chamber, which ensures a good distribution of the various components before the material is swallowed by the extruder screw.

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