Injection Blow Moulding

Injection Blow moulding is a process whereby a blow moulded bottle can be produced with a much more precise neck thread and top rim finish for better seals than a standard blow-moulded bottle. This is a 2-step process where in the first step a preform is injection moulded to create the precise thread/top rim. A core pin creates the inner diameter of the preform - usually a uniform parallel inner diameter and the cavity of the tool forms the outer - usually parallel to the inner diameter. This preform often resembles a test tube-like shape with a screw thread at the top. In some cases the preform is transferred immediately to the second step on the same machine or in other cases is transferred to the second step after a period of several days/weeks. The second step is where the bottle shape is blown. In the case of immediate transfer the bottle is blown in a mould where the pressure of air blown into the neck expands the polymer to take the shape of the bottle. Where the second step is perfromed some time later, a pre-heating stage is required to soften the polymer preform to allow the blowing step to be facilitated. Once the blown bottle has been allowed to cool, the mould opens and allows the finished bottle to drop out and be transported away. In the continuous process, each step is carried out in a rotating carousel with the preform injection at 90º to the blowing stage which again is at 90º to the cooling stage and finally at 90º to the ejection stage. When the preform is blown some time after, the preforms are fed into a pre-heat oven or exposed to infra-red heaters to bring them up to the correct temperature, before being transferred to the blowing stage to form the final bottle shape. Typical Materials Used:

Polyethylene (HDPE, LDPE, (LLDPE), Polypropylene (PP), Polyethylene - Terephthalate (PET), Polyvinyl chloride (PVC), Polyethylene (High Density) HDPE)