In case of physical foaming, the gas dosing station injects the gas (propellant) into the extruder under high pressure via an injection valve. The gas quantity can be adjusted directly and adapted to the polymer and the foam density to be achieved.

At the tool outlet, a sudden, large pressure drop leads to a supersaturation of the melts with the propellant. The gas is again released from the polymer and thus forms a consistent, microcellular foam structure.

As well as the low raw material consumption, the significant characteristics of this production process are positive product properties, such as low density, exceptional heat and sound insulation, mechanical damping, low levels of water vapor permeability and reduced moisture absorption.

Further advantages are a homogeneous foam structure, very good process stability and low propellant costs.