Extrusion blow moulding

Extrusion blow moulding is commonly used to produce hollow parts such as bottles, canisters or irregularly shaped containers. The thermoplastic material is first melted in an extruder, the melt is then conveyed through an annular die and formed into a hollow tube or parison. In the second step, a two-part mould closes around the parison, creating the typical pinch-off weld on the bottom. A mandrel is inserted into the upper end of the parison and compressed air is applied so that the preform is pushed to the tool wall. At the same time, the neck region of the hollow part is formed. The part can be removed as soon as it has reached a sufficient strength.