packaging
PET Preform
A small, injection-moulded PET part that is heated and blown into a finished bottle in stretch blow moulding.
A PET Preform is the precursor part used in stretch blow moulding. It is injection-moulded from PET resin in a separate process (preform injection moulding machine) and supplied to bottling plants either by an in-house injection line or by external preform suppliers.
Key preform parameters:
- **Weight (g):** 12–25g for 500ml–1L water bottles; 30–55g for juice and CSD; 650–800g for 20L jars.
- **Neck finish:** ROPP, PCO 1810 (water), PCO 1881 (lightweight), 28mm screw, 38mm wide-mouth, etc.
- **Resin grade:** food-contact PET (Reliance Sila series, Indorama RamaPET, IVL preforms), IV value typically 0.78–0.84 dL/g.
A consistent preform supply is critical to consistent bottles, IV variation of even 0.02 changes wall thickness distribution noticeably. Most established water plants tie up with one validated preform supplier per neck finish.
Related terms
PET Blow Moulding
A bottle-forming process that uses heated PET preforms expanded by high-pressure air inside a bottle-shaped mould.
Neck Finish (PCO 1810 / 1881)
The standardised geometry of a PET bottle neck and corresponding closure, defines cap compatibility, preform sourcing, and capping head selection.
IV (Intrinsic Viscosity) Value
A measure of PET resin molecular weight, directly affects bottle wall thickness, drop-impact resistance, and pressure tolerance.
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