When temperatures rise in summer or production sites are located in hot climates, blown film manufacturers face an additional challenge in production: the film bubble cools more slowly at high hall temperatures and therefore tends to stick together (block) after being laid flat. In the worst case, the film is then unsaleable. To avoid such blocking, manufacturers reduce the output of the line or increasingly use anti-blocking additives at hot temperatures.
"At high hall temperatures, manufacturers have previously been faced with the trade-off between reduced output or higher material costs to avoid blocking," says Daniel Lamers, who is responsible for the CENTRO-Freeze series at Kdesign, the cooling technology specialists for blown film lines. "With our CENTRO-Freeze secondary cooling, producers can maintain their usual line output even under hot ambient temperatures and save on anti-blocking additives - improving their profitability."
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The CENTRO-Freeze is installed immediately before the flat lay and is a supplementary cooling system to increase output and save material costs in case of blocking problems. The air blow-out elements of the CENTRO-Freeze cool the film tube evenly around the entire circumference and thus enable a cooling of the film temperature by up to 12 degrees Celsius, reliably preventing blocking of the film.
The additional cooling capacity makes manufacturers independent of the ambient temperature and allows them to run their line on hot days just as they do in winter. This provides planning security: "A prolonged heat wave can completely disrupt the production schedule," says Lamers. Manufacturers then risk delivery delays or have to use expensive anti-block additives to meet deadlines, which in turn reduces their margins. "An investment in the CENTRO-Freeze usually pays for itself after just one or two heatwave summers," says Lamers.
Suitable for new and existing lines
The CENTRO-Freeze is suitable for all new blown film lines as well as for retrofitting in existing lines. For new lines, it also reduces the required hall height, since the cooling capacity replaces part of the cooling distance between the die and the layflat. This means that lines with high output can also be installed in a hall that is actually too low.
"For retrofits, the CENTRO-Freeze is the most compact secondary cooling solution on the market and can be installed even in very limited space," says Lamers. This is because, compared to alternatives from other manufacturers, the cooling system has integrated roller guide elements that replace the support cage of a blown film line.
The system is also much more flexible than a rigid secondary cooling ring: The CENTRO-Freeze automatically follows the bubble diameter so that no changeover work is required when changing formats. The distance between the cooling elements and the film bubble therefore remains constant during format changes. This ensures uniform cooling performance at all times.
