The Stork co-extrusion blowmoulding machine manufactures lightweight HDPE and PP bottles. These are available both in open, non-sterile and in closed, internally sterile versions. In addition to manufacturing single-layer bottles, the co-extrusion blowmoulding machine is capable of fabricating three-layer and six-layer bottles.

The three-layer bottle prevents the transmission of light, while the six-layer version reduces oxygen and light permeability. The bottles can be blowmoulded in both open-type and closed-type versions.

During the blowmoulding process employ-ed for closed-type bottles, sterile air or nitrogen is fed to inflate the parison trapped between the mould halves to form a bottle, the extended neck section of which is squeezed together just prior to the blow-moulded bottle being released from the mould. This ensures that the bottle is sealed and internally sterile.

The co-extrusion blowmoulding machines allow ease of re-tooling to suit other bottle sizes in that only the moulds need to be changed by purposely designed quick-release couplings.