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Leno-Woven NCF enhancing medical applications

News International-French

1 Mar 2016

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A perfect pairing of partnership and potential – Successful co-operation enables computer-tomography patient couches made from newly-developed leno-woven carbon non-crimp fabric

Research for the textile future – that is the slogan of the Research Institute for Textile Technology Albstadt mbH (FTA) as  part of the Groz-Beckert Group. Together with the company of Schmuhl Faserverbundtechnik GmbH & Co. KG, a successful optimization in the manufacture of patient couches in computer tomography has been realized.

As part of a basic research project, the Groz-Beckert Posileno system for the production of leno fabrics was adapted on a rapier weaving machine to enable production of both unidirectional and bidirectional non-crimp fabrics (NCF).

Laboratory tests at the FTA have shown that especially the unidirectional NCFs have better drapeability, shorter infusion times, and better mechanical properties than the unidirectional fabrics based on conventional multiaxial technology that served as a benchmark.

To evaluate the industrial potential and customer benefits of this technology, applications and also component manufacturers have been identified for testing the new textiles. Here, Schmuhl Faserverbundtechnik GmbH & Co. KG proved to be a competent and innovative partner.

The Schmuhl Faserverbundtechnik has more than 20 years of experience in the manufacture of sophisticated plastic products, especially in the area of high-strength composites. Schmuhl also develops and produces patient couches for computer tomography (CT). These couches have a sandwich construction with a foam core and carbon-fiber textiles, i.e. 0°/90° fabrics and several unidirectional NCF- layers. The high number of unidirectional NCF-layers had to be applied since the single layer weight was restricted to 300 gsm in order to fit the geometry of the couch without causing any shifts in position during the insertion process or any folds in the NCF when the mold was closed. This in turn led to increased manufacturing costs.

To reduce the lay-up time, while maintaining the quality and also realizing a better weight-related cost for the textile, the target was a tripling of the single layer grammage combined with high fabric drapeability. At the same time, any adverse effects on the treatability and workability of the textiles as well on the physical and mechanical properties were to be avoided.

For this requirement profile, a leno-woven NCF with a grammage of 900 gsm made from heavy-tow carbon yarns was successfully developed by the FTA.

Schmuhl successfully realized lining of the molds with the expected time savings. The textile structure prevents any unwanted shifts in the layers during insertion of the reinforcement materials or during closure of the mold. In addition, the improved treatability was also evident in the process used by Schmuhl, in the form of shorter infusion times. Furthermore, there was a positive influence on surface quality.

The results of the experiments at Schmuhl were such positive that the leno-woven carbon NCFs were selected for the couches and have meanwhile entered series production. In addition, production is also starting for a second product for the use in the medical industry. Here, the material was preferred because of the experience gained in prototype production: The component surface can be significantly better realized in comparison to currently available warp-knitted unidirectional materials.

Similar potential for leno-woven NCF are seen among others in automotive industry, e.g. composite leaf springs, in wind energy, e.g. longeron flanges or trailing edge reinforcements, or in sport industry, e.g. ski.

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