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Pooling and expanding expertise
Center for Textile Lightweight Engineering
Since its founding in 1992, the STFI has been dedicated to the field of textile lightweight engineering. Starting with the development of semi-finished products based on endless rovings, from 2005 of recycling of high-performance fibers grow as a new field of research. At first, these pioneering works were clearly ahead of time. But the demand for small-scale tested / industry-oriented recycling strategies and technologies has grown rapidly since 2010, especially in the area of carbon fiber reinforced semi-finished products. After that the developments of the STFI were honored by the Federal Ministry of Economics in 2013 with the receipt of the “German Resource Efficiency Prize”.Recognizing the signs of the times, investments were made in expanding this department. With the opening of the newly built Center for Textile Lightweight Engineering in Chemnitz in May 2017, the STFI was able to set an important milestone.In addition to the semi-industrial process for processing carbon fiber waste into nonwoven, the production of test specimens and components in form of thermoplastic or thermosetting composites based on a wide variety of technologies is a second focus of work. The Center for Textile Lightweight Engineering is completed by an integrated testing laboratory, which is designed for the special needs of lightweight textile structures. Here, accredited tests on high-performance fibers, semi-finished textile products and fiber-reinforced plastics can be carried out directly on site.Further investments have already been made to expand the existing technical equipment. These include the addition of a fiber opening technology, a fiber mixing plant as well as an aggregate for inline application of preparations into the production line for nonwovens from high-performance fibers. The technologies for composite production will also be further expanded. For example, an interval hot press will offer the possibility of processing textile rolls to organic sheets in continuous operation. From 2018 on, this will allow us to fully take into account strategic challenges of research as well as the individual needs of industrial clients.
Dipl.-Ing. (BA) Marcel HofmannManager Center for Textile Lightweight Engineering
Sächsisches Textilforschungsinstitut e. V.An-Institut der Technischen Universität ChemnitzAnnaberger Straße 240 · 09125 Chemnitz · GermanyTelefon +49 371 5274-0 · Fax +49 371 5274-153Management: Dipl.-Ing.-Ök. Andreas Berthel,Dr.-Ing. Yves-Simon Gloy
Technical Equipment
Nonwoven production linen
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cutting and tearing machine to convert different kinds of textile waste material (consisting of high performance fibers) into processable staple fibers.web forming by use of 100% carbon fibers or blends of carbon fibers with synthetic and / or natural fibers based on the carding process (by using MiniCard and cross lapper) or airlay process (by using airlay machine K12 direct)inline mechanical bonding methods: needle-punching and / or stitch-bonding processable raw material: 100% carbon fibers, blends of carbon fibers combined with PP, PA, PES, PEI, PPS, PEEK, glass- or natural fibers
processable fiber length: 30 – 120 mmworking width: 500 – 1000 mmworking speed: max. 4 m/minpossible area weight: 40 – 1500 g/m²
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Production of rCF-sliversn
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consisting of staple fibers (100 % carbon fibers or fiber blends)inline bonding method to obtain a strand-like productproduction of cylindrical tubes resp. flanged bobbin
processable fiber length: 60 – 100 mmworking speed: 4 – 10 m/mindiameter: 8/12/16 mm bonding by using hotmelt
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n rCF-suitable Cetex Lab-Spinning-Machine (LSE-C)processable material: slivers or rovesspinning process: ringspinning process (Siro/Core)number of spinning stations: 6
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n carding, stretching and tape production by using fiber blends (rCF, natural fibers, thermoplastic fibers)„
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processable fiber length: 60 – 100 mmtape area weight: 100 – 600 g/m²tape width: ¼ – 12 inchworking speed: 4 – 20 m/min
2013
Technical Center for Fiber Composites
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Technologiesmanufacturing of fiber reinforced plastics based on
thermoset matrix: epoxy resin, polyester resin, PURthermoplastic matrix: PP, PA, PPS, PEEK, PEIreinforcing fibers: carbon, glass, basalt, aramid, natural fibers in shape of different textile fabrics like woven fabrics, non-crimp fabrics and / or nonwovens
NC-controlled cutting binder application and preforming model and mold makingproduction of organic sheets composite production methods:
hand lay-up ®vacuum infusion (incl. VAP -method)
resin-transfer-molding (RTM) technologypressing methods
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n CNC-Cuttercut surface: 1.600 x 1.350 mmcutting heads: draw blade, active or passive roll knife,
oscillating knives
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injection methods®vacuum infusion (incl. VAP -method)
RTM technology (cold or warm curing)heating cabinet (up to 300°C)mechanical processing of laminates
high precision circular sawband sawNC-milling machinedifferent grinding machines
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Machineryhydraulic downstroke press
press capacity up to: 2.000 kNpress area: 900 x 600 mmmax. temperature: 420 °Cheating rate: up to 20 K/mincooling rate: 10 K/mininfrared preheating station with automated transport between preheating station and press
laboratory presspress area: 320 x 320 mmmax. temperature: 400°C
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Technical Equipment
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Matrixhybride - material and technology development for form-locked and cohesive bonding of thermoplastic and thermoset FRP laminates
Aim of the research project Matrixhybride is to combine both matrices in a composite material in order to be able to add thermoset FRP components by means of welding processes. The new material and technology development closes a previously existing serious gap for joining processes in the composite sector.
The combination of both matrix materials should be achieved in addition to the adhesive forces between thermoplastic and thermoset by the form-locked connection of reinforcing fibers, which permanently change the matrix side by the undulation of the woven fabric. The project focuses on carbon fibers and high performance matrix materials for aerospace, automotive and marine applications.Funding: , duration 10/2017 - 03/2020. Zwanzig20 – Partnerschaft für Innovation
Figure: Draft of a matrix-hybrid compound
Thermoset matrix Fabric layer
Interface
Thermoplastic matrix
Testing of Composites
Special services on high-performance fibers and composites
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Sample preparationproduction of sample plates sample cutting (rectangle, dumbbell-shaped)preparation of tabsapplication of strain gaugeroving impregnation
Testing methods:fiber lengthfiber fineness / densityfiber tenacity and modulus fiber matrix bonding (pull-out test)roving fineness / density / tensile force (with / without impregnation)tensil test according DIN EN ISO 527- Serie, DIN EN 2561, DIN EN ISO 14129 (shear stress) bending test according DIN EN 2562, DIN EN ISO 14125, DIN EN 2746interlaminar shear strength (ILSS) according DIN EN 2563, DIN EN ISO 14130compression test according ASTMD 6641, DIN EN ISO 14126
Contact:
Dipl.-Ing. Marian Hierhammer +49 371 [email protected]
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Research Highlights
The rapidly in-creasing manufac-turing of carbon fiber reinforced plastics (CFRP) for lightweight struc-tures is leading to
suitable production waste for recycling. Additionally to the development of nonwovens made of recycled carbon fibers and processed by carding technology, a process for sliver formation and in-line consolidation was developed.Result is an axially symmetric, flexibly windable, rope-shaped textile semi-finished product (secondary roving).
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Roving from reprocessed carbon staple fibres
Aim of the project was the development of a new generation of textile semi-finished products for fiber composites based on pre-impregnated rovings (towpregs) and their processing on knitting machines. The project specifically investigated the production of pre-impregnated, binder-free, two-dimensional knitted fabrics (uni-directional, bi-directional, multi-directional) for preforming. The technical challenge was to reduce the negative impact of the tack on towpreg abrasion / mass loss behavior and to reduce contamination of machine elements.In the first part of the project towpregs of the most important manufacturers, such as Vitech, TCR, Red Composites and SGL, were considered on a special test bench to determine the abrasion behavior. In the second part of the project, trials to produce knitted fabrics were carried out successfully.
Manufacturing of Towpregs as semi-finished products for composites
Figure: uni-directional non-crimp fabric made out of towpregs
Based on the towpreg semi-finished products laminates were produced by pressing and their mechanical properties were determined.
Funding: INNO-KOM-Ost, duration 04/2016 - 03/2018
The project EUCALIVA (EUCAlyptus LIgnin VAlorisation for Advanced Materials and Carbon Fibres) focusses on utilization of lignin waste from paper pulp industry. It's focusing on developing and setting-up a fully-integrated, energetically-efficient, scalable, innovative and flexible system based on the valorization of lignin for producing carbon fibers. There are estimated 70 million tons of lignin available from pulping processes worldwide, which are not isolated but burned onsite to provide steam for heat and power production.EUCALIVA will be dealing with three fundamental aspects in the preparation of high quality carbon fibres, taking lignin as source from black liquor:
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optimization of lignin derivation, preparation (e.g. blends with other polymers) or by introducing metal or other precursors into the spinning solution for lignin fibers; development of faster thermostabilization routes andachieving new or enhanced properties of carbon fibers for structural and functional applications.
From eucalyptus waste to carbon fibres - EUCALIVA
Figure: towpregs on knitting machine
EU-framework programme Horizon 2020 „Bio-Based Industries Joint Undertaking“ (BBI JU), duration 09/2017 - 03/2021
Contact
Recycling, rCF-NonwovensManager Center for Textile Lightweight EngineeringDipl.-Ing. (BA) Marcel Hofmann ( +49 371 5274-205
Lightweight Engineering, Composites Christopher Albe, M. Sc. ( +49 371 5274-241
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rCF-Nonwovens, Composites Katharina Heilos, M. Eng. ( +49 371 5274-227
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Composite Testing(*
Sliver and yarn manufacturingDipl.-Ing., Dipl.-Wirt.-Ing. Ina Sigmund
( +49 371 5274-203*
Lightweight Engineering, Composites, Component preparationDipl.-Ing. Günther Thielemann ( +49 371 5274-239
Dipl.-Ing. Marian Hierhammer +49 371 [email protected]
The RecyCarb project is supposed to close the gap between actual rCF products available on the market and functional re-use of carbon fiber reinforced plastics in high quality parts.Therefore, several solution processes are pursued:
process scale-up of waste recovery and nonwoven production with regard to quality requirementsset-up of process-integrated monitoring system by quality parameters and initiation of a reliable scheme of quality assuranceevaluation of different nonwoven technologies effects
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This project enables specific application-oriented adaption of developed technology and products to the different requirements of target applications and potential end-users.
Within this project, infiltration of rCF-nonwovens will be inves-tigated by using the HP-RTM-process and the Wet Com-pression moulding technology in cooperation with Fraunhofer ICT. Besides the nonwoven manu-
facturing process (airlay and carding), bonding methods like needle-punching or stich-bonding will be considered regarding their quality of impregnation and achievable mechanical properties. The infiltration process will be performed by Fraunhofer ICT suitable for series production.Furthermore, this project offers new ways of using production waste or end of life material by providing more cost-effective pro-ducts on the market. Compared to products based on primary fibers, components made of rCF-nonwovens show decreased mechanical properties. Nevertheless, these products offer sufficient strength and stiffness especially for light weight constructions focused on weight reduction.
Memberships
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R E C Y C A R B
ALLIANZ TEXTILER LEICHTBAU
VliesRTM RecyCarb
ImprintSächsisches Textilforschungsinstitut e. V., An-Institut der TU Chemnitz Annaberger Straße 240 · 09125 Chemnitz · GermanyEditor: Dipl.-Des. (FH) Berit LenkPhotos: STFI, W. Schmidt, I. Escherich; Editorial deadline: February 2018
Funding: Industrielle Gemeinschaftsforschung, duration 01/2017 - 06/2019
Funding: Zwanzig20 – Partnerschaft für Innovation, duration 12/2016 - 11/2018
