Injection Stretch Blow Moulding is the process of manufacturing high quality and very high clarity bottles.
The plastic is melted and then injected into a mould to form a preform. The preform is then pre heated before being held inside two halves of a mould. When the preform is in the mould it is then inflated using high pressured air while simultaneously being stretched. While the plastic is inside the mould, the plastic will freeze off to the mould shape as it is forced against the inside of the mould. The mould halves will then open releasing the bottle so that the process can be repeated.
PET - Polyethylene Terephthalate
The most commonly used material is PET - Polyethylene Terephthalate - and is used to compete with bottles made of glass. Bottles blown using PET can give the following advantages:
- Good barrier characteristics against carbon dioxide and oxygen
- Excellent clarity, nearing that of glass
- Lighter weight bottles can be made
- High breakage resistance to avoid risk and injury
- Dimensionally very accurate bottles
- Thermally stable, suitable for hot filling
- Suitable for recycling
- PCR (post consumer recycled) material is now also becoming more common as it utilises recycled PET offering a more environmentally friendly alternative