Preform Cooling Method Boosts Bottle Output

A preform-cooling system developed by W. Amsler Equipment Inc., Richmond Hill, Ont., has permitted a leading Canadian blow molder to realize significantly higher output for thick-walled PET liquor bottles. The system increases air flow in the oven to reduce the surface temperature of the preform. This is said to minimize temperature differentials throughout the preform, thus inducing less stress and allowing faster molding cycles with no loss in quality. Moreover, higher air flow is said to improve production of colored bottles, reducing the chance of burning the colored preforms.

The system uses the same infrared heating elements but replaces the standard reflectors with a plenum chamber. Air flow through the plenum slots cools each preform directly and more precisely. Instead of compressed air, Amsler relies on its standard integral filtered-air supply with no additional power consumption.

PET blow molder Westbridge Inc., Calgary, Alta., installed the system on its Amsler two-cavity reheat stretch-blow machine and realized a 13.3% improvement in productivity for thick-walled (0.210-in.), 1.75L liquor bottles. Westbridge shaved a second off its cycle time, producing 1107 bottles/hr vs. the previous 960/hr.

“We were able to heat the preforms at a higher temperature while still keeping the outer surface cool,” said Harry Logan, the molder’s director of operations. “By the time the preforms reached the blowing station they maintained a uniform heat profile throughout their wall thickness, resulting in a significantly reduced cycle time.”