Pultrusion

An important research aspect of the Pultrusion Department is the sampling of newly developed resin systems, textile semi-finished products, and fiber and sizing systems.

Due to extensive expertise in the processing of all common matrix systems (polyester, vinyl ester, epoxy, polyurethane, etc.), special resins and standard fiber types (carbon, glass, basalt, etc.) and special fibers, the processability of different materials can be investigated. Together with our customers, we work on further developing and optimizing semi-finished products to produce composites with maximum performance.

Read our customer references here: Covestro
 

A central development aspect of many research and customer orders is the individual adaptation and further development of our plant technology.

Fraunhofer IGCV has an extensive machine park on an industrial scale. This is constantly growing according to projects and requirements. Therefore, we are happy to support our customers in the individual adaptation and further development of their plant technology.

A special field of activity in pultrusion technology is fiber and semi-finished product guidance.

This is a demanding challenge, especially for larger profiles and the use of semi-finished fiber products. Due to years of experience in the pultrusion of complex geometries and reinforcement types, the layout and design of fiber and semi-finished product guidance can be implemented without problems to ensure smooth pultrusion.

A core competence of Fraunhofer IGCV is the design and layout of pultrusion tools.

In addition to the pultrusion- and production-oriented design, special customer requirements can be realized and, for example, further functional elements can be implemented in the tool.

In order to obtain a fiber-reinforced plastic (FRP) profile with the highest possible mechanical properties, the basis is an optimal impregnation of the fiber material by the resin matrix.

In addition to the impregnation variants of the open impregnation bath ("straight-through-bath"), which are common in the pultrusion process, the method of an injection and impregnation chamber is increasingly used. This can be integrated into the mold or installed separately upstream of the mold. The decisive factors here are the use of resin systems with low pot lives (e.g. polyurethane) and the reduction of emissions.

In order to be able to optimally exploit the advantages of an injection and impregnation chamber in a specific application, a design of the chamber geometry and the injection concept is indispensable and represents a core competence field of the Pultrusion Department at Fraunhofer IGCV.

Factory planning can be divided into several levels.

One of these levels is the process level, in which, for example, a pultrusion process is considered. On the next level, this pultrusion process is linked to the upstream and downstream processes to form a process chain. The optimal planning of such a process chain and its subsequent integration into an existing production system or the conceptual design of a new production system are central issues in factory planning.

Due to the convergence of process knowledge around pultrusion and planning expertise from various factory planning projects within the IGCV, we are happy to advise you on all questions in this area.

As a research institute that focuses on application orientation, we are involved in numerous funded research projects.

Together with our partners, we conduct application-oriented research close to the market in order to achieve the greatest possible benefit for our customers and to develop and promote innovations for society.

A selection of completed and current research projects:

• PulForm: Energy-efficient production of complex high-performance fiber composite components by means of pultrusion, in-line braiding, blow molding and finishing
• PULaCell: Bio-based polyurethane reinforcement lamella with cellulose fibers for wood constructions
• AIF functional elements in intralogistics
• ZIM oscillating coil
  
  

In the age of Industry 4.0, it is essential to enable direct communication and cooperation between man, machine, plant, logistics and product.

Against this background, pultrusion technology, as one of the oldest manufacturing processes for continuous fiber-reinforced plastics, is also to be raised to a new digital level and intelligent and sensible machine networking is to be established: Pultrusion 4.0. We have already demonstrated our concept for this in a research facility and we support our partners in the realization of individual solutions in their companies.

In order to answer questions such as "Is it worth a new production process?", "What are the effects of integrating a new process?" or "How profitable are alternative process chains?" accounting tools are often used as decision support.

They can provide statements on a wide range of target parameters such as sustainability, profitability, quality or even energy efficiency. Thus, investment decisions can be made in a well-founded manner and new, target-size-optimized alternatives can be shown. Fraunhofer IGCV has the process knowledge as well as the experience in cost and life cycle assessment for the pultrusion process to reliably answer your questions.

The load-path-compatible design of pultrusion profiles is carried out by a simulation team specialized in composites.

Here, a deeper understanding of the material behavior of anisotropic materials and the corresponding material modelling is available. The portfolio in structural simulation ranges from static load cases to crash calculations. With the help of the latter, the complex failure behavior of pultrudates can be represented.

An important aspect of application-oriented research includes the transfer and combination of technologies with the pultrusion process.

The "PulForm" project enables energy-efficient production of complex high-performance fiber composite components by means of pultrusion, in-line braiding, blow molding and finishing.

The transfer of our theoretical and practical experience in the pultrusion process to our partners is implemented by means of specially tailored training courses. The contents can be taught at the basic level or can be specifically related to an application. In addition to the theoretical basics, the practical experience directly on the pultrusion line is irreplaceable for everyone who wants to get deeper into pultrusion.

To obtain a detailed understanding of the processes involved in the impregnation of the fiber material by the resin system, the use of impregnation simulations is essential.

This makes it possible to identify potential problems for the specific application and to take countermeasures at an early stage, e.g. by modifying the injection and impregnation system.

Areas of investigation include the resin flow through the fiber package (permeability behavior), the heat transfer between the mold and the pultrudate, and the resin system's curing reaction. As important material parameters, the reaction kinetics and the viscosity course of the resin system during curing as well as the compressibility and permeability of the fiber material are considered. The necessary characteristic values can be determined at the institute.

In the pultrusion process, even small deviations in the process parameters or in the hardware can lead to problems.

This can cause a deterioration of the profile quality or even make continuous pultrusion impossible. Recognizing such problems and presenting appropriate solutions is part of the expertise of the Pultrusion Department at Fraunhofer IGCV 

Our expertise in the processing of different types of resin systems:

We support you in the development and validation of your specific resin systems. You benefit from our know-how at an early stage and can draw on our support until series production is ready:

• Standard resin systems: vinyl esters and unsaturated polyesters
• High-performance resin systems: epoxy (amine and anhydride curing systems) and polyurethane (aromatic and aliphatic PU)
• Special systems: bio-based resins, hybrid resins and acrylates, etc.

Our expertise in the processing of different types of fibers and textiles:

We support you in screening and selecting the type of fiber and fiber types as well as the textiles for laminate construction. We have extensive experience in roving, mats, scrims, fabrics and other semi-finished textile products and braids.

The assembly of semi-finished textile products in the institute or in close cooperation with specialized partners enables short reaction times for the optimization of laminate structures during development campaigns.

Infrastructure and pultrusion tools:

Fraunhofer IGCV has a large number of pultrusion tools that can be used with both closed and open impregnation methods. The infrastructure of the pultrusion pilot plant includes comprehensive process data acquisition (pressures, temperatures, forces etc.). By interpreting the data with pultrusion experts at Fraunhofer IGCV during development campaigns, maximum efficiency of process development is guaranteed.

• Pultrusion equipment:
  • Pultrusion I: max. Pul-Force 100 kN | 500 x 250 mm²
  • Pultrusion II: max. Pul-Force 80 kN | 750 x 350 mm²
  • Pultrusion III: max. Pul-Force 20 kN | bars and small profiles
• Mixing and metering equipment:
  • 3k mixing and metering plant
  • 2k mixing and metering unit for epoxy as well as polyurethane
  • 1k dosing plant for epoxy
  • 1k metering unit for various polymer systems
• Variably combinable caterpillar haul-off | max. pul-force 25 kN
• Variable double-ring plaiter
• Large selection of pultrusion tools for closed and open impregnation processes

• Strauß, S.; Hecking, A.: „Neue bio-basierte PU-Matrix für bewitterungsstabile Verbundwerkstoff-Anwendungen“, Allianz Faserbasierte Werkstoffe Baden-Württemberg, Virtual Conference, Nov. 2021
• Strauß, S.: „Development of a flexible injection and impregnation chamber for pultrusion of high reactive resins“ 23rd International Conference on Material Forming, Virtual Conference, May 2020
• Strauß, S.: „Pultrusion of Polyurethane and Applications“ 15th World Pultrusion Conference, Antwerp (Belgium), Feb. 2020
• Wilhelm, F.; Strauß, S.; Reiner C.: „Influence of power ultrasonic on the impregnation of unidirectional fibers in closed injection pultrusion” 22nd International Conference on Composite Materials (ICCM22), Melbourne (Australia),  Aug. 2019
• Strauß, S.; Meisenheimer R.; Hecking A.; Senz A.; Wilhelm, F.: „Manufacturing of predominatly bio-based composite profiles with pultrusion” 22nd International Conference on Composite Materials (ICCM22), Melbourne (Australia), Aug. 2019
• Strauß, S.: „Flexibility in Polyurethan Injection Molding“, North American Pultrusion Conference, Rosemont (United States), Apr. 2019
• Wilhelm, F.; Wiethaler J.; Karl R.: „Power ultrasonic in closed injection pultrusion”, 18th European Conference on Composite Materials (ECCM18), Athen (Greece), Jun. 2018
• Wilhelm F.; Strauß S.: „Current pultrusion research topics at Fraunhofer IGCV”, World Pultrusion Conference, Vienna (Austria), Mar. 2018
• Wilhelm, F.: „Closed injection pultrusion”, BMBF Travelling Conference ReHCarbo, Shanghai (China), Jeonju (South Korea), Bangkok (Thailand), Nov./Dec. 2017
• Strauß, S.: „Complex hollow structures by pultrusion and bladder molding“ BMBF Travelling Conference ReHCarbo, Shanghai (China), Jeonju (South Korea), Bangkok (Thailand),  Nov./Dec. 2017
• Bezerra, R.; Henning, F: „Modelling and simulation of the pultrusion process with closed injection and impregnation molds”, 17th European Conference on Composite Materials (ECCM17), Munich (Germany), Jun. 2016
• Bezerra, R.: „Manufacturing of Complex Shape Composite Parts through the Combination of Pull-Braiding and Blow Moulding”, 13th World Pultrusion Conference, Prague (Czech Republic), March 2016
• Wilhelm F.; Bezerra R.; Strauß, S.: „Serienfertigung von hochleistungsfaserverbundbauteilen komplexer Geometrie,“ 1. Compoform Tagung, Munich (Germany), May 2015
• Bezerra, R.; Wilhelm, F.; Strauß, S.; Ahlborn H.: „Manufacturing of complex shape composite parts through the combination of pullbraiding and blowmoulding”, 20th International Conference on Composite Materials, Copenhagen (Denmark), Jul. 2015
• Ahlborn, H.; Bezerra, R.; Middendorf, P.; Drechsler, K.: „PulForm – Herstellung komplexer FVK-Bauteile mittels Flechtpultrusion und Blasumformung“ 24. Stuttgarter Kunststoffkolloquium, Stuttgart (Germany), 25.-26.02.2015
• Bezerra, R.; Wilhelm, F.; Henning, F: „Compressibility and permeability of fiber reinforcements for pultrusion”, 16th European Conference on Composite Materials (ECCM16), Seville (Spain), Jun. 2014

• Bezerra, R; Wilhelm F. et al.: „Energieeffiziente Herstellung komplexer Hochleistungsfaserverbundbauteile mittels Pultrusion, In-Line Flechten, Blasumformung und Endbearbeitung”, Stuttgart, Fraunhofer Verlag, 2016

• Bezerra, R: „Modelling and Simulation of the Closed Injection Pultrusion Process“, Ph.D. Thesis, Fakultät für Maschinenbau, Karlsruher Institut für Technologie, Karlsruhe, Germany, 2017

• Wilhelm, F.;  Strauß, S.; Weigant R.; Drechsler K.: „Effect of Power Ultrasonic on the Expansion of Fiber Strands”, Journal of Composites Science, 4(2) 50, 2020
• Tucci, F.; Bezerra, R.; Rubino, F.; Carlone, P.: „Multiphase flow simulation in injection pultrusion with variable properties”, Materials and Manufacturing Processes, 35:2, 152-162, 2020
• Strauß, S.; Wilhelm, F.: „Development of a flexible injection and impregnation chamber for pultrusion of high reactive resins”, Procedia Manufacturing, Vol. 47, 2020
• Wilhelm, F.; Strauß, S.; Kronseder, M.: „Influence of power ultrasonic on the viscosity of epoxy resin”, Results in Materials, 2020
• Mentizi, S.; Hecking, A.; Strauß, S., Achten, D.; Guiteras, M. A.: „Aliphatic polyurethan matrix for sustainable UV-resistant composites“, Revista de la Asociacion Espanola de Materiales Compuestos, Vol. 3 No. 4, 2019
• Strauß, S.; Senz, A.; Ellinger, J.: „Comparison of the Processing of Epoxy Resins in Pultrusion with Open Bath Impregnation and Closed-Injection Pultrusion“, Journal of Composites Science, 3(3), 87, 2019
• Linganiso, L. Z.; Bezerra, R.; Bhat, S.; John, M.; Braeuning, R.; Anandjiwala, R. D.: „Pultrusion of flax/poly(lactic acid) commingled yarns and nonwoven fabrics”, Journal of Thermoplastic Composite Materials, Vol 27, Issue 11, 2014