Slashing PET preform cooling

NISSEI ASB’s Zero Cooling PET technology targets increased productivity and container quality by modifying the standard moulding method in the company’s four-station, one-step ASB Series line-up.

‘Under the Zero Cooling technique, preforms leave the injection mould immediately after completion of filling and packing, with no allowance for cooling time. As the mould opens the preform skin is set just stiff enough to resist any deformation so that it can be safely de-moulded and transferred to the preform conditioning station, where all necessary cooling is applied together with any temperature optimisation. This frees up the injection mould immediately for the next injection cycle,’ explains Corné Pretorius, GM of Nissei ASB South Africa.

The result is an average 35% reduction in overall machine cycle time compared to standard one-step moulding, as well as an average 1.5 times increase in output. Crucially, these fast cycle times can be achieved while avoiding the need for thin, nonoptimised preforms that are susceptible to several undesirable quality problems such as ‘orange peel’, ‘body ring’ and ‘fisheye’.

Corné points out that the preform design has been updated to a smaller and thicker format with a higher stretch ratio. This modification has resulted in excellent material distribution, increased visual quality and an average top-load strength of 15% more than standard moulding.

These qualities provide more scope to apply additional lightweighting to a container’s specification. The advanced cooling method also enables the moulding of heavyweight, premium cosmetic containers (using standard PET grades) in very short cycle times, without any visible haziness.