MATERIALS | THERMOPLASTIC COMPOSITES


Right: Window plates made with Krauss- Maffei’s FiberForm are 20% lighter than the metal originals


increase productivity, cut wear costs and reduce maintenance.


Window plugs KraussMaffei has helped the US-based National Institute for Aviation Research (NIAR) to produce window plugs made of thermoplastics composites, to replace heavier metal versions. The plugs were needed when passenger planes


were temporarily converted into cargo planes during the Covid pandemic. They were showcased at the NPE show in the US last year. Among other tasks, passenger-to-cargo conver-


sions require replacing acrylic window plugs with metallic alternatives for ease of maintenance. This could be optimised with fibre-reinforced thermo- plastic composites – which are cheaper, lighter and faster to produce than the metallic part. The parts were made using KraussMaffei’s


FiberForm technology, in which a fully consolidated fibre-reinforced thermoplastic sheet – known as organosheet – is inserted into the tool, formed and overmoulded with a thermoplastic polymer. For the window plugs, this was done on a GXW 450-2000/1400 with swivel platen. The plug was designed with the oval-shaped geometry of the original with appropriate design modifications, such as adding stiffening ribs so it could withstand pressure loads. It was made from LM-PAEK rein- forced with AS4 carbon fibres for the 16-ply organosheet and 30% chopped-fibre-filled Peek for overmoulding the ribs. The short cycle time is a major advantage of fast injection moulding compared to metal machining: 40 window closures can be produced in an hour. In addition, the thermoplastics used for FiberForm offer the possibility of welding components, have a high impact strength, are resistant to high tempera- tures, chemical and environmental influences and are flame-retardant. The metal part weighed 590g, while the compos- ite part is 20% lightert. The team is further optimis-


Right: DCIM helped Fiber Dynamics to cut cycle times for its in-house designed propeller blades


IMAGE: NIAR


ing the structure to make it around 40% lighter. The next step for the NIAR program is to subject the window plugs to further functional tests required for certification – for example with regard to durability – so that it is ready for series production. “KraussMaffei set up a machine with multiple capabilities, and has been actively helping us on-site with process development,” said Waruna Seneviratne, director of NIAR Atlas. “Our goal is to transfer the efficient processes such as FiberForm from automotive production to aviation.”


Direct action


NIAR was also involved in a separate project – help- ing local company Fiber Dynamics to develop propeller blades for a new type of ‘air taxi’. The company had been using a Lost Core


Tooling System (LCTS) – but it was taking too long, had formulation limitations and was too costly. After discussions with KraussMaffei, it switched to a new method – and tested it at NIAR. “KraussMaffei quickly understood our problem


and offered its DCIM technology,” said Darrin Teeter, CEO of Fiber Dynamics.


As well as having cycle times up to eight times faster than its previous LCTS technology, DCIM – or Direct Compounding Injection Moulding – helped Fiber Dynamics with its own recipe control. The company has now invested in a GX 1100-4300 DCIM system. “The ability to test different formulations and quickly develop new ones is crucial to the success of our programme,” he said. “Externally com- pounded formulations are generally not practical for our work and jeopardise the proprietary nature of our solutions.”


DCIM combines injection moulding and compounding in a single process. A single-screw extruder handles the material preparation, making the process cost-effective for smaller components with a shot weight of 50-2000 . Material savings of up to 50% per kilogram can be achieved. The


36 INJECTION WORLD | January/February 2025 www.injectionworld.com


IMAGE: FIBER DYNAMICS


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