Tag Archives: dry preform

Why the use of NCF is growing in complex structural components

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NCFs are a type of “engineered fabrics” to reinforce polimeric composites that are made up of multiple layers or fibers stitched together. The most used NCF’s are biaxial, triaxial and cuadriaxial fabrics, where the fiber tows are straight and with different orientations (0, 45, 90 degrees) to provide multidirectional properties.

Non  Crimp FabricImage: Non Crimp Fabric

The combination of multiple layers of fibers, stacked in just one fabric, leads to faster and cheaper preforms production processes than unilayer based processes. It also has advantages for LCM (Liquid Composite Moulding) methods as NCF present better drappability due to the good deformability of unidirectional plies versus vowen fabrics that are undulated (crimp). An additional advantage of the NCF reinforced composites is that they generally feature better mechanical properties as the tows are not crimped or woven. Furthermore the delamination resistance and impact strenght of the NCF reinforced composites is better.

One key advantage of the NCF’s is the ability to drap into relatively complex shapes without giving rise to wrinkles that normally appear with standard woven textiles and preimpregnated tapes. The excelent conformability of biaxial fabrics under “dome type” deformation conditions is caused by a slipage of the fiber tows as there is no joints that restrict this movement.
This is why the use of NCF is rapidly growing in aircraft, automotive, yatching , wind energy and complex structural components.

A lot of work is being done in NCF to push the boundaries of this materials:

Research is beeing developed to increase the limits of the deformability of NCFs through the determination of the best stitching conditions. These studies show that the deformation of the biaxial y triaxial NCF under load (bias extensión test), happens through rotation, sliding and compaction of the tows. The resistance of the NCF to biaxial deformation is dependant on the density, the tension and the position of the stitches. Higher tension on the stitches gives bigger resistance to deformation due to better sliding resistance.

The veils and binders used by the different suppliers play also an important role. A veil is a thin layer of polimeric material formed by fibers with random orientation. Binders are thermoplastic particles that act like an adhesive. Nowadays they are used to minimice fragility of the epoxi matrix on the composite.They also avoid fraying or wrong orientation and specially optimize the permeability, improving process times. Permeability of the material is a key feature. On one hand high permeability accelerates infusion processes, on the other hand too much space between the fibers can lead to a worse impregnation of the fibers worsening the fatigue behaviour. Many innovations are beeing lauched in these topics.

The manufacturing requires handling and depositing the NCF on the mouls with big precision, repeatability and productivity. Drappability modeling is also an important research area , predicting and improving the deformation of the fabrics depending on the tension applied is the basis for the good part design and process optimization.

In this line developments like Drapetest http://bit.ly/1wu2Sm4 allows to automatically characterize drapability and the formation of defects during draping and forming The tester combines the measurement of the force required for forming with an optical analysis of small-scale defects .

Video: Bombardier CSeries uses NCF

JEC Europe 2014: innovative products, aimed at dry preform manufacturing and infusion

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The most innovative products aimed at dry preform manufacturing and infusion where shown in JEC Europe 2014,  the most important trade fair of composites industry that took place in Paris between the 11th and 13th of March. The fair keeps showing a great level as long as it refers to expositors and visitor numbers, as for the quality and quantity of products and innovations that were presented.

The big possibilities that this material offers are already being exploited in all kind of industries and the biggest issue is now the increase of productivity and the improvement of production costs.
In this post we  have highlighted some innovative products, aimed at dry preforming and infusion,  that drew the attention of the DRY COMPOSITES team.

MATERIAL HANDLING SOLUTIONS
Schmalz showed its solutions for the composites industries, with its range of vacuum and needle grippers for carbon and glas fiber fabrics handling. According to them, they will be launching  briefly electrically operated grippers, which will offer great benefits to those proffesionals who want to avoid the costly compressed air.

Also with the interesting quality of the flexibility to addapt to the desired geometry, Fraunhofer IPT presente two new solutions. An-Octopus Kinematic gripper which is adapted easily to the deposition point, as well asflexible shaped electrostatic grippers.

Schmalz´s and Fraunhfoer IPT´s grippers

Schmalz´s and Fraunhfoer IPT´s grippers

FLEXIBLE DEPOSITION HEADS

AFPT presented its multimaterial, head winner of the JEC innovation Award 2014 wich is able to process thermoplast tapes, duroplast prepregs and dry fiver rovings. The head was originally developed by Fraunhoffer IPT. The head is constructed in a modular way and it can be adapted to different fiber materials, such as glass and carbon fibers, as well as various matrix materials on the same equipment, using lasers.

AFPT´s flexible deposition head

AFPT´s flexible deposition head

COMPLETE PROUDUCTION CELLS
Companies such as Dieffenbacher or Fives, presented its fully automated cell for composites parts manufacturing. By acquiring the Relay machinery, expertise and intellectual property rights of Fiberforge, Dieffenbacher is investing in the automated tape placement technology, both dry material placement and also adding a key technology to its product portfolio in the growing market for thermoplastic structural components for lightweight design. Hi Pressure Resin Transfer Molding machinery by Kraus Maffei was also presented in the exhibition

Dieffenbacher´s cell for composites parts manufacturing

Dieffenbacher´s automated cell for composites parts manufacturing

AUTOMATED WIND BLADE MANUFACTURING SOLUTIONS: MAPRETEC PROJECT
An interesting German government funded project was presented at the Show. Saertex, Areva and Bremen University have developed together a new solution for the automated wind blades manufacturing. It consists of a new and innovative approach based on the two-dimensional automated layup of single NCF layers to a multiple stack followed by the forming of the final contour into a 3D preform.

Mapretec´s project

Mapretec´s project for automated wind blade manufacturing

SOLUTIONS FOR FRPP COMPONENTS PRODUCTION WITHOUT RELEASE AGENTS
Fraunhofer IFAM presented 0,3 micrometer thick plasma-polymer release layer that leaves no residues of release agents on either the component or the mold.

Fraunhofer IFAM´s thick plasma-polymer

Fraunhofer IFAM´s thick plasma-polymer

DRAPABILITY CHARATERIZATION SYSTEMS
Textechno presented DRAPETEST, a new automatic drapability tester, that has won the JEC Innovation Award in 2014. The solution to automatically characterize drapability and the formation of defects during draping and forming. the tester combines the measurement of the force, which is required for forming, with an optical analysis of small-scale defects such as gaps and loops by means of image analysis. An optional triangulation sensor can determine large-scale defects such as wrinkles

Textechno´s drapability characterization system

Textechno´s drapability characterization system