PETpla.net Insider 06 / 2017

PREFORM PRODUCTION PET planet Insider Vol. 18 No. 06/17 www.petpla.net 10 PREFORM special right amount of barrier material for a given application while maintaining a robust productivity. It is well known that material cost is a major contributor to the total cost of a package. Barrier materials, while making up a relatively low (typically 2 -15%) percentage of a package’s weight are substantially more expensive than PET. This makes it critical to ensure the minimum nec- essary amount of barrier material is delivered to each mould cavity and dis- tributed in the most effective manner within the preform. This level of advanced control is only possible with a fully integrated system that utilises a unique, state- of-the-art hot runner design. The hot runner is based on technology that enables an unprecedented level of balance, even before any controls are tuned for the application. This reduces the number of times melt flow is split in the hot runner, which is the single most significant contributing factor to hot runner imbalance. This hot runner technology also provides design freedom, optimising melt channel layouts of two mate- rial melt delivery systems for a high degree of thermal control. Many barrier materials have a lower melt- ing point and are more temperature sensitive than PET. Overheating and excessive residence time may lead to material degradation. This not only impacts preform and bottle quality, but can also increase hot runner refur- bishing intervals. Injection moulders familiar with co-injection will recognise that in the attempt to improve hot runner balance and ensure melt flow and tempera- ture rates are as uniform as possible across multiple gates, the hot runner may be tuned by lowering and raising temperatures of manifolds and nozzle tips. Husky hot runners are designed to provide control flexibility through an increased number of manifold zones and individually temperature controlled tips. Traditional pneumatic actuation of valve gates has been upgraded to an electric servo, plate actuated synchronous valve gate system. At the same time, the high level of balance means that the range of temperatures used in further tuning the performance is reduced, further decreasing the maximum temperature experienced by barrier material. When running temperature sensi- tive barrier materials, purging both hot runner melt delivery systems with PET during system shut-down and re- start is a good practice that has been automated. Even the best mainte- nance practices may leave room for unplanned events, such as contamina- tion of source resin by foreign material. If a contamination particle finds its way into the hot runner, the most likely area for a blockage is the hot runner nozzle. It has been notoriously difficult to clean this area, often requiring complete hot runner disassembly. The HyPET HPP5 barrier system features a front removable nozzle design, which allows the maintenance or replacement of hot runner nozzles while in the press, by latching over the mould cavity plate to expose the tips. While co-injection moulding is still more complex than traditional mono- layer injection moulding, the operation of the complete system is facilitated by Husky’s preform-centric control system, integrating all aspects of the injec- tion moulding process and auxiliary equipment. Process setup for a new application begins with establishing a monolayer process for preform quality. When barrier material injection is ena- bled, the control system automatically adjusts the PET injection profile based on the barrier content and generates the barrier injection profile, which can be fine-tuned by the operator. Multi-Layer Technology offers a complete, integrated solution for manufacturing food and beverage products requiring enhanced barrier properties that is highly cost-effec- tive, productive and flexible. It allows brand owners to rely on PET for more appealing packages that stand out on store shelves and support conversion from alternate materials, all factors that help to support the growth poten- tial of PET packaging. www.engineeredpackage.com Husky’s Multi-Layer Technology is suitable for a variety of applications, including for carbonated soft drinks, mineral waters, juices, sauces, and now seeing expansion into dairy, beer and personal care products. Conventional manifolds split the melt channels many times, which creates shear related imbalance.