Thermoforming
Thermoforming Sustainable packaging made of natural fibres Plastics know-how shapes the future of cellulose packaging As a technology partner in the various areas of the plastics and packaging industry, KIEFEL (Freilassing, Germany), also supports its customers in the development of biodegradable materials and products. With Fibre Thermoforming, the company has opened up a complementary field of technology utilising natural fibres incorporating decades of know-how from plastics processing into the development of the Fibre Thermoforming machines. New material – various opportunities In addition to classic recyclable plastics, the company can now process fibre-based as well as recycled (e.g. rPET) and biobased (e.g. PLA) materials. Virgin fibres (unprocessed cellulose) can be used to comply with food industry regulations for packaging solutions made from paper. This means that Kiefel can provide the optimal product development and production technology, regardless of which material the customer chooses. The raw material for fibre products is pulp or paper dissolved in water. This is shaped, pressed, dried, and converted into dimensionally stable packaging that can be recycled in the paper cycle or even composted. This means, depending on the application, they offer an alternative to plastic packaging made from renewable raw materials and with a low CO 2 footprint. This is possible by an extensive machine portfolio for the production of fibre packaging: The NATUREPREP KFP series for high-quality natural fibre pulp stock preparation and the NATUREFORMER KFT series systems, on which various fibre products, including bowls, cups, secondary packaging for electronics, coffee capsules, or flower pots can be manufactured. Matching coating concepts make the products grease and water-repellent, and suitable for warm drinks, hot food, or persistent moisture. Discovering the potential of natural fibres In its own Material R&D Center, Kiefel researches, analyzes, and categorizes various natural fibres and designs coating concepts for packaging made from natural fibres. These are then tested on pilot systems and optimized for the manufacturing process. The Material R&D Center complements Kiefel’s Applied Polymer Research Center in the Netherlands, which focuses on materials research into recycled and biobased plastics. In the adjacent Packaging Technology Center, the company tests materials under real conditions: it tests tools on the systems, carries out machine tests and small batch sample production. Prototype testing also takes place here. Kiefel offers turnkey solutions for Fibre Thermoforming. The engineering in Fibre Thermoforming The pulpers of the Natureformer KFP series process fibres common in the paper industry (primary or secondary fibres), e.g., CTMP (chemi-thermomechanical pulp), NBSK (northern bleached softwood kraft), UKP (unbleached kraft pulp), ONP (old newsprint or old newspaper), OCC (old corrugated cardboard or old corrugated containers). The Natureformer KFT series processes the raw cellulose pulp in batches to a 1 % fibre content. Flow simulations ensure that the fibres are evenly distributed over the container volume. The aluminium suction tool with V2A stainless steel mesh is immersed in the suspension. The vacuum applied sucks up liquid and the cellulose fibres remain in the tool, similarly to a filter cake. A spray bar removes excess pulp and defines the edge of the product at regular intervals. The suction tool then moves into a flexible counter tool of the pre-pressing station. Richard Hagenauer heads the Fibre Thermoforming project at Kiefel. He explains: “These steps guarantee even fibre distribution across the entire tool geometry, excellent dimensional accuracy and a very high-quality surface.” After this step, the dry content reaches approximately 40 %. The suction tool then transfers the component to the hot press. Any remaining moisture is eliminated by 24 bioplastics MAGAZINE [04/21] Vol. 16
Thermoforming Product diversity of formed fibre products temperatures around 200°C in the upper and lower tools and a clamping force of up to 600 kN. Hagenauer explains: “Our technology allows us to achieve drawing depths of up to 250 mm on the Natureformer KFT 90 Flex. We work with cavities directly heated by heating cartridges integrated into the tool. This enables us to achieve optimal heat transfer, reduce energy consumption, and achieve high product quality.” Fast tool change The suction tool is mounted on the handling robot and transfers the component from station to station. The KFT 90 Flex is equipped with a fully automatic rapid tool change system. Hagenauer describes the benefits: “The heated tool can be changed within 15 minutes. This makes it possible to quickly reconfigure the machine from one product to the next.” The handling robot traverses to tool positions for maintenance, cleaning, and tool change. Automation and Quality Management The sophisticated Natureformer KFT series automation solutions include a tilting and stacking function, Flex-Picker, sleeving station and automation up to and including packing into cartons. Quality control and inspection systems can be integrated, as well as peripherals for printing, labelling or similar intermediate steps. These various automation modules and their ability to be linked allow the Freilassingbased company to meet specific customer needs. The machines are experiencing high demand – several have already been delivered to Europe and the USA, and many more are already on order. This makes Kiefel the first manufacturer of plastic thermoforming machines to also offer highly automated systems for fibre thermoforming. MT www.kiefel.com Natureformer KFT 90 Kiefel explores the potentials of different natural fibres in its Material R&D Center (all photos: Kiefel) bioplastics MAGAZINE [04/21] Vol. 16 25
