A carbonated bottle has to hold pressure for months, so the blow-molding window matters as much as the preform weight. Three levers do most of the work — and none of them has a universal setpoint, because every mould and machine differs.
Even reheat
Uneven preform reheat is the classic cause of a thin shoulder or an off-centre base. Aim for a smooth temperature profile down the preform so the wall stretches evenly — especially when lightweighting, where there is less material to forgive a cold spot.
Base & mould cooling for the petaloid
The petaloid base carries the CO₂ load. Firm, consistent base and mould cooling sets that geometry crisply; under-cooling leaves a soft base prone to creep (stress whitening, rollout) once pressurised.
Validate burst before you scale
Before a production run, confirm burst and long-term creep at your actual carbonation level — not just at fill. This is non-negotiable for a lighter wall.
Size a burst-safe preform and check the stretch fit first in the Preform Engineering calculator; final blow and capping parameters are set by Delta El Nile engineering.
Frequently asked questions
Why does my CSD bottle have a thin shoulder or off-centre base?
Usually uneven preform reheat. Aim for a smooth temperature profile down the preform so the wall stretches evenly; an imbalanced oven leaves a thin shoulder or off-centre base.
How do I cool the petaloid base on a CSD bottle?
The petaloid base carries the CO₂ load — firm, consistent base and mould cooling sets that geometry crisply. Under-cooling leaves a soft base prone to creep and rollout.
Should I burst-test a lightweighted CSD bottle?
Yes, non-negotiably. Before a production run, confirm burst and long-term creep at your actual carbonation level (not just at fill) — especially for a lighter wall.
What are the key process controls for blowing a CSD bottle?
Even reheat for an even wall, firm base/mould cooling for a crisp petaloid, and validated burst and creep at the real carbonation level before scaling.
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