Lighter, smarter, better lightweight construction

Louise Davis

Claude Maack introduces an innovative process technology designed for lightweight construction

When glass, carbon, natural and other fibres types are aligned according to the desired component functions and wound multi-dimensionally, spatial ultra-lightweight and stress-optimised components are created. The technological process from the idea to the finished component is called xFKin3D process. xFKin3D describes a technological contribution to integrative lightweight construction of the future. It is a concrete and measurable resource-saving process of raw materials versus other manufacturing processes. It can be implemented in highly innovative lightweight construction solutions in various technological areas. However, the concept, choice of materials, type of fixtures and production ways must be defined from the very beginning in the preliminary design phase.

In the construction of complex global structures such as car, aircraft or satellite, it is crucial that stiffness, strength, temperature changes and geometrical tolerances are known. These are essential criteria that must be considered, mastered and processed wisely for the manufacturing of fibre composite components. The same applies to the xFKin3D process, which is characterised by a highly flexible, cost-effective and sustainable design to obtain innovative and unique ultralightweight parts.

In the past, endless wound components were mainly limited to rotationally symmetrical applications, such as tanks or tubes in 2½D. The continuous fibre technology xFKin3D is, suitable for non-rotationally symmetrical components such as brackets and other complex support elements. It reinvents the endless winding process to a higher “D” level, i.e. it enables parts of 3D, 4D & even 5D to be produced, bringing intelligent functions to the structure if required. Any kind of fibres such as carbon, glass, or natural fibres such as basalt, flax, rayon can be used. The thermoset used matrix is typically in most cases epoxy resins. However, it can also be realised by using Tow-Pregs (pre-impregnated fibres with the polymerisation process stopped). This is a competitive advantage, as no autoclaves are needed. Additionally, bio based resins can be used, which are cured at atmospheric pressure. For some applications, thermoplastic polymers can be used.

The technology was successfully used for the first time in 2016 by the company AMC for high-end sports cars. Since then, continuous investments have been made in the development, marketing, technologisation and industrialisation of this manufacturing process.

As weight can be reduced by 70% compared to bionic optimised aluminium parts, Airbus called the process technology a ‘step-change’ and BMW is talking about a ‘gamechanger’.

xFKin3D is a highly innovative and is characterised by a number of technical features, notably its ultralight, high geometric flexibility (e.g. bionic design) and optimised bionic topography. Other key features include the fibre design being based on load direction and the fact the process is force and tension optimised (fibre strength/direction according to load). It features definable/adjustable strength and stiffness and multi-axial load capacity (tension/compression, bending, torsion). It is also material-optimised/resources friendly (almost any offcut). Finally, it features integration of functions in the component, making it into an intelligent “5D” component.

Ultra-lightweight construction

In terms of stiffness and especially tensile strength, it is not possible to build “lighter” because “only” as many fibres as necessary are used to fulfil the requirements. Therefore, we speak of an additive manufacturing process of ultra-light construction. “Industry 4.0” is on many people’s lips and is understood as the digitalisation of industry. The targeted networking of industrial structures in an effective networking of efficient software applications is of importance here – i.e. the process from the idea and concept through simulative development and testing to the final production of the component. This is where xFKin3D process technology comes in for ultra-lightweight construction, as the product creation process can be accelerated with this innovative method. Here, calculation and simulation determine the entire subsequent product creation process – the process technology is de facto calculation/simulation-driven, based on the principle “form follows force”. Therefore, we also speak of a “full digital process chain”.

Since 2019, parts for the automotive industry have been automatically wrapped with Tow-Preg. Gradel is developing a nine-axis winding machine based on an industrial robot. The first tests have been running since May 2020 and the process technology will be qualified for flight hardware in aerospace and aeronautics until the end of 2021. The qualification is being carried out in close collaboration with ESA and the OEMs for large satellites and an European aircraft manufacturer.

Covid-19 has increased social awareness on different important topics, including resource efficiency, energy efficiency and sustainability. xFKin3D contributes perfectly to these subjects.

Claude Maack is managing director at Gradel


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