The Process

Blow moulding is used to create hollow enclosed components and there are two basic types of technology: extrusion blow moulding and injection blow moulding. In extrusion blow moulding a parison or tube is produced by extrusion. A mould is then closed around the parison and the product is blown into the shape of the mould with compressed air. In injection blow moulding two moulds are used. A mandrel or blowing stick is placed in the first mould, and the thermoplastics material is then injected into the mould flowing around the mandrel to create a tube. This is then transferred to the second mould where air is introduced to expand it to the shape of the mould. A variation on this method is stretch blow moulding whereby the material is biaxially oriented to produce stronger products. This method is particularly used for the manufacture of PET bottles.

There are more than 1,300 blow moulders in Europe and AMI publishes a number of directories that describe the companies which carry out this process.