“1+1 equals -1”: New hybrid fibre eliminates one process step



Gustav Gerster GmbH & Co. KG has now achieved an important step: The company has created a hybrid textile that combines reinforcing fibres and a plastic matrix in one woven fabric.

The suitability of a component for series production is very much determined by its cycle time, i.e. the time in which the component can be manufactured by the respective machine. Lightweight structural components made of fibre composites require a high handling expenditure, because they need to be repositioned within the machining cell. This can be a limiting factor. German manufacturer Gustav Gerster GmbH & Co. KG has now achieved an important step: The company has created a hybrid textile that combines reinforcing fibres and a plastic matrix in one woven fabric. Despite the woven-in matrix, the textile remains highly drapable and is suitable for near-net-shape forming. Because of this, it could replace the organic sheets previously used in the manufacturing process.

The Development Agency for Lightweighting Baden-Württemberg presents this innovation in its September 2020 edition of ThinKing. Under this label, Leichtbau BW GmbH provides a platform every month for new innovative lightweighting products or services from Baden-Württemberg.

At a glance:
- Time- and cost-saving: A significantly simpler process for manufacturing lightweight components
- Complex structures due to the flexural flexibility and excellent drapability of the textiles
- Efficient use of materials: Less waste thanks to good shape adaptability
- Improved mechanical component properties due to reduced wrinkling and stable fibre arrangement

For lightweight components made of fibre composites, it has become increasingly popular in recent years to create variants with a thermoplastic matrix. The semi-finished products being used for this are often organic sheets in the form of consolidated, cut-to-size laminates that have been manufactured from endless reinforcing fibres and a plastic matrix. To mould the component, the organic sheet must be reheated and then modified into shape.

“The idea behind Drapfix and Draptex Hybrid is to eliminate a heating step in this process,” says Annika Muckenhaupt, Project Manager for Composites at Gustav Gerster GmbH & Co. KG, Business Unit Gerster Tech-Tex. “For this purpose, we use hybrid textiles where the thermoplastic matrix is already contained in the yarn. Then, all that is required is to lay the textile into the component that is to be reinforced or into the mould, and then simultaneously heat and form it.”

Drapfix and Draptex Hybrid are both biaxial fabrics (0°/90°) with endless reinforcing fibres and a thermoplastic matrix, made from hybrid yarns. The hybrid yarns are created during the spinning process, which ensures that both materials – glass fibre and thermoplastic – are homogeneously distributed in the yarn.

The even distribution of both materials in the yarn – and thus also in the textile – results in particularly short flow paths for the thermoplastic when the semi-finished product is melted. This in turn results in short cycle times during the production of the fibre-reinforced component. These times vary and depend on the component and the combination of fibre and matrix chosen for the respective textile.

Direct forming has so far led to the successful production of demonstrators using glass fibres and PP (polypropylene) as the matrix. Components made from Drapfix/Draptex Hybrid using glass fibres and PA (polyamide) as the matrix are currently being tested.

„Natural fibres, such as linen, are also conceivable as reinforcing fibres,“ says Annika Muckenhaupt, adding that in this area, however, development is still in the early stages.

Textiles adapt to complex structures without wrinkling

When the hybrid material is inserted directly into the mould (i.e. the component to be reinforced or the tool), the good drapability of its base textile, Drapfix, allows it to adapt to the mould without wrinkling. This makes forming much easier and improves the mechanical properties of the component. The fibres retain the desired orientation and position within the textile – and thus within the finished component.

From a textile-technical point of view, the reason for this is the freely movable fibres. During production, the fibres are distributed manually or automatically with the help of small rollers. Complex geometries such as corner angles or deep troughs can be draped in just one step. Due to its excellent drapability, this biaxial fabric is particularly suitable for highly complex structures.

This is also one of the major distinctions between this alternative product and organic sheets: Thanks to the flexural flexibility of the textile and the special weave, the hybrid material can adapt very well to any given geometry – even in cases where an organic sheet would reach its limit in terms of drapability, for example.

Hybrid textile saves time and money

Due to the textile’s ability to supply adapt to the mould, it becomes possible to omit a work step or two. One such step is the reworking of the component, for example the need to cut the corners to minimise wrinkling.

In addition, the highly drapable hybrid fabrics allow for near-net-shape forming. Therefore, the use of Drapfix/Draptex Hybrid not only offers time- and cost savings; its efficient use of materials during the entire process also supports the cost-effective production of components.

“In general, the hybrid biaxial fabric simplifies the consolidation and forming of components due to its textile properties,“ Annika Muckenhaupt explains. She is convinced that the lightweight material offers extensive industrial applicability and a “comfortable” manufacturing process.

Possible areas of application include the automotive and aerospace industries. Manufacturers of commercial vehicles or caravans, too, could benefit from this material, as could manufacturers of sports equipment. Gustav Gerster is currently looking for industrial partners to jointly advance the development of this innovative hybrid material all the way to series production.

About Gustav Gerster GmbH & Co. KG – Business Unit Gerster Tech-Tex

Gerster TechTex is a specialist manufacturer of technical textiles. One of the company’s main focusses lies on reinforcing materials for the composite market. Another field of application is auxiliary and operating materials based on narrow textiles, which are used to improve efficiency in industry. The manufacturer’s product range includes standard and special structures made from glass, aramid and carbon as well as synthetic yarns, e.g. PES fibres.