Process Encyclopaedia
Blow moulding
Overview
Blow moulding is most commonly a batch process used to produce simple drinks bottles. Clever design of the blank allows the screw top and base of bottles to be thicker than the walls.Materials and shapes
- Used for simple, thin-walled, hollow products - mainly bottles
- Used with thermoplastics, mainly PET.
- Good, smooth surface finish can be readily achieved.
- Depending on how the hollow blank (parison) is made, scrap can be negligible.
- There is a variant which is continuous and used to produce thin-walled tubes which can be slit to make cling-film or plastic bags.
Economics
- The production speed is limited by opening and closing the mould, so automation is normally used.
- Production rates from a few hundred to a few thousand per hour can be achieved.
- The tooling and machines are moderately expensive (£10,000 - £100,000).
- Moulds may need to be replaced after about 100,000 uses.
- Only used for high volume products with batch sizes of 100,000+.
Typical products
Bottles and containers up to 0.5 litreExternal links
Science museum animation.