PETpla.net Insider 01+02 / 2018

CAPS & CLOSURES 30 PET planet Insider Vol. 19 No. 01+02/18 www.petpla.net Caps 4.0: smart and efficient injection moulding by Michael Birchler, Head of Marketing and Communication at Netstal Netstal injection moulding solutions provide users with reliably functioning closures at a minimum cost per unit. Simultaneously, the current trend is towards increasingly more intelligent machines that, assisted by data, are capable of independently regulating connected peripheral systems. At Drinktec 2017, Netstal highlighted the advantages of the injection moulding process and demonstrated how production operation and monitoring will be significantly simpler in future. CAPS & CLOSURES Many contemporary closure designs distinctly favour injection moulding over compression mould- ing. “Injection moulding especially comes into its own in the production of lightweight and thin-walled standard closures, where cleanly moulded thick- ness geometries can be manufactured in huge numbers with a high level of reliability,” explained Stefan Müller, Sales Director Asia Pacific at Netstal. In contrast, the material volumes used for these closures are much too small for the compression process. Qual- ity problems may arise because the plastic cools off too quickly in the cavity before it can be formed in the mould. Contrastingly, boasting short cycle times, a high number of cavities and low power consumption, a high-perfor- mance injection moulding system from Netstal’s Elion series offers a high level of productivity. As an example, an Elion 4200-2900 equipped with a 96-cavity mould can produce around 170,000 type 29/25 closures per hour. At an overall availability level of 95%, the annual output of a single line would be approximately 1.4 billion units. Low cost per unit on the basis of state-of-the-art hybrid technology The optimised energy efficiency of injection moulding machines has played a decisive role in reduc- ing unit costs. “Hybrid systems in operation today often only consume around half the power that their fully hydraulic predecessors used,” declared Müller. In the case of the aforementioned 29/25 closure, the electricity consumption of the entire system is a mere 0.56kWh per kilo of material. An additional plus point is the comparatively small footprint required by an injection moulding system. “Every injection process on an injection moulding machine pro- duces finished closures complete with fully functional tamper-evident bands. This eliminates the need for separate process stages such as the cutting and folding of tamper- evident bands,” explained Peter Schmid, Netstal’s Applications team leader. Injection moulded lightweights with precision- formed lip seals First a closure must fulfill one primary and decisive task: reliably seal the bottle. The contents should not run out and outside impurities must not pass into the beverage. This is achieved by lip seals located on the inside of the closure. Particularly in the case of very thin lightweight models, the forming of these lip seals is extremely challenging as a result of the brief process window and minimum material volume. Injection moulding enables the manufacture of a reliable seal even with these closure models. “The principle advantage of the injection moulding process on high-precision Netstal machines is that depending on the application and closure type, the material is injected at processing temperature in less than 0.2 of a second. This enables mould- ing and shaping of the finest lip seals that later reliably protect the bottled beverage,” said Schmid. The high-performance Elion 3200-2000 machine from Netstal shown at the Drinktec 2017