New process chains for composites:

Integration of preforming, impregnation, forming and curing

When the FOR 860 research group started its investigations, the manufacturing techniques to produce high-performance components of fibre-reinforced plastics (FRP) were able to meet only some of the set targets. Up to that point in time, for example, geometrically complex components could only be produced within a short period of time if using injection moulding, compression or RIM (Reaction Injection Moulding) techniques.   

The FOR 860 research group is titled “New process chains for composites: integration of preforming, impregnation, forming and curing”. The group is concerned with considering the production of continuous FRPs in a holistic approach, starting from roving to final component. Its major target is to improve the manufacturing techniques applied with respect to suitability for series production. In doing so, the scientists look into three process chains, all of which start with manufacturing the fibre prepregs and end in a component ready for use.

Research target of FOR 860

In the scope of research undertaken by the group, the complete value creation chain is submitted to a holistic consideration, starting from roving to final component. As part of the process chains, the production stages of “preform production”, “impregnation” and “forming and curing” are considered and added crucial investigations in the areas of handling. There were three significant targets to be considered:

  • Production of continuous fibre reinforced high-performance components with fibre volume contents higher than 50 % to achieve superior weight-specific mechanical properties  
  • Implementation of process chains with cycle times under 10 min
  • Demoulding of parts with little need for secondary finishing

IKV works on the following sub-projects:

The aim of sub-project 4, PU spray impregnation, is to analyse and evaluate the impregnation concepts for near-net-shaped textile preforms with integrated functional elements. The fibre semi-finished products considered are impregnated completely and air entrapments are avoided. The complexity of the preforms to be impregnated is due to a curved surface with varying thickness or to functional element integrated into the preform, for example inserts, breakthroughs and reinforcing structures. Moreover, the sub-project is aimed at targeted control of the impregnation process, keeping excess resin as a result of spraying within defined limits. Another objective of the investigations is to improve handling of this prepreg system, and reduce cycle times to below 10 min., too.     

Publications

Michaeli, W.; Strohhäcker, J.; Pöhler, M.: Spray impregnation technology for continuous fibre composites. 26th Annual Meeting of the Polymer Processing Society, Banff, Kanada, Juli 2010

Hopmann, Ch.; Michaeli, W.; Pöhler, M.; Fischer, K.; Lambrecht, L.: Resin Spray Prepregging – High volume capable manufacturing process for structural composite parts with polyurethane matrix. 27th Annual Meeting of the Polymer Processing Society, Marrakech, Marokko, Mai 2011 

Hopmann, Ch.; Pöhler, M.: Resin Spray Prepregging – Structural parts with non-foaming polyurethane matrix. Sampe Conference 2012, Baltimore, Maryland, USA, Mai 2012

Hopmann, Ch.; Fischer, K.; Pöhler, M.; Schöldgen, R.: Resin Spray Prepregging – Integration and impregnation of inserts for high performance parts. 28th Annual Meeting of the Polymer Processing Society, Pattaya, Thailand, Dezember 2012

Michaeli, W.; Winkelmann, L.; Pöhler, M.; Wessels, J.: New process technology for high volume production of composites. Journal of Polymer Engineering, 31 (2011) 1, S. 63-68

Michaeli, W.; Wessels, J.: Formgebung und Vernetzung flüssig imprägnierter Preforms im Pressverfahren. Zukunftsgespräche Leichtbau: Neue Großserienverfahren – Neue Möglichkeiten für Composites, Aachen, Juli 2010 

Michaeli, W.; Bastian, R.; Fischer, K.; Pöhler, M.; Wessels, J.; Winkelmann, L.: Großserientaugliche Fertigungstechnologien für Leichtbau-Produkte aus faserverstärkten Kunststoffen. Leichtbau-Kongress auf der euroLITE, Nürnberg, Juni 2010

Michaeli, W.; Pöhler, M.; Winkelmann, L.: Großserien-Fertigungstechnologien für Leichtbauprodukte aus faserverstärkten Kunststoffen. Lightweight Design (2011) 1, S. 18-25

Hopmann, Ch.; Pöhler, M.: Kompakte Polyurethane mit Endlosfaserverstärkung. PU Magazin, September/Oktober 2012, S. 313-318

Within the process chain of high-pressure impregnation, the process stage of „impregnation“ is separated, in terms of space and time, from the stage of “forming and curing”, so as to reduce the cycle times required to manufacture continuous fibre reinforced plastic components. The aim of high-pressure impregnation is to generate near-net-shaped, low-porosity, impregnated textile preforms within short cycle times. The scientists were able to implement an in-line quality assurance system as part of the high-pressure impregnation process chain, which makes it possible to evaluate the preform’s impregnation quality prior to subsequent processing in sub-project 8. 

Publications

Michaeli, W; Strohäcker, J.; Winkelmann, L.: New process chain for the automated manufacturing of structural FRP. 26th Annual Meeting of the Polymer Processing Society, Banff, Kanada, Juli 2010

Michaeli, W; Winkelmann, L.: Resin Transfer Prepregging – Fertigung von Strukturbauteilen in kurzen Zyklen. 17. Nationales Symposium des SAMPE Deutschland e.V., Aachen, Februar 2011

Michaeli, W; Winkelmann, L.: New Process Chain for the Volume Production of Structural Composite Parts. SAMPE 2011, Long Beach, USA, Mai 2011

Michaeli, W.; Winkelmann, L.; Pöhler, M.; Wessels, J.: New process technology for high volume production of composites. Journal of Polymer Engineering, 31 (2011) 1, S. 63-68

Hopmann, Ch.; Schöldgen, R.; Fischer, K.; Fecher, M.L.: Analysis of the impregnation process during the Resin Transfer Prepregging process. 28th Annual Meeting of the Polymer Processing Society, Pattaya, Thailand, Dezember 2012

Michaeli, W; Bastian, R.; Fischer, K.; Pöhler, M.; Wessels, J.; Winkelmann, L.: Großserientaugliche Fertigungstechnologien für Leichtbau-Produkte aus faserverstärkten Kunststoffen. Leichtbaukongress auf der euroLite2010, Nürnberg, Juni 2010

Michaeli, W; Winkelmann, L.: Großserientaugliche Fertigungstechnologien für Leichtbauprodukte aus faserverstärkten Kunststoffen. Lightweight Design, (2011) 1, S. 18-25

Hopmann, Ch.; Fecher, M.L.: Resin Transfer Prepregging – Process chain for large scale production of structural composite parts. Tagungsband 6th CFK-VALLEY STADE CONVENTION, Stade, Juni 2012

Hopmann, Ch.; Fecher, M.L.; Pöhler, M.; Wessels, J.: New process chains for serial production of fibre-reinforced plastics. Materials Science and Engineering, Darmstadt, September 2012

In order to perform systematic process analysis and to implement the gap impregnation technique into an automatic production process, an all-automatic gap impregnation plant was installed as part of this sub-project at the technical centre of IKV, in 2009. The plant is designed to automatically produce structural components with functional elements. Parameter analyses are carried out to investigate optimum production parameters for the production of uniaxially curved components as well as flat parts with functional elements integrated, for the case of reduced cycle times. With all process stages automated, and process control optimized, the investigations aimed at reducing cycle times to below 10 min, at fibre volume contents higher than 50 %.  

Publications

Michaeli, W.; Bastian, R.; Fischer, K.; Strohhäcker, J.: Gap-impregnation: A high volume capable process for manufacturing structural composite parts. 26th Annual Meeting of the Polymer Processing Society, Banff, Kanada, Juli 2010

Hopmann, Ch.; Bastian, R.; Fischer, K.; Schoeldgen, R.: Analysis of the production of composite parts with functional elements using the Gap Impregnation process. 28th Annual Meeting of the Polymer Processing Society, Pattaya, Thailand, Dezember 2012

Michaeli, W.; Fischer, K.: Spaltimprägnierverfahren für schnellere Herstellung von Hochleistungsbauteilen. Lightweight Design (2010) 1, S. 48-54

Michaeli, W.; Bastian, R.; Fischer, K.: Automatisierte Fertigung von Hochleistungsbauteilen mithilfe des Spaltimprägnierverfahrens. Tagungsunterlagen 25. Internationales Kunststofftechnisches Kolloquium des IKV, Aachen, März 2010

Michaeli, W.; Bastian, R.: Spaltimprägnierverfahren vs. RTM-Verfahren: Reduzierung der Taktzeiten durch neuartige Anlagentechnik. 17. Nationales Symposium SAMPE Deutschland e.V., Aachen, Februar 2011

Fischer, K.: Neue Ansätze zur großserientauglichen Fertigung struktureller Bauteile aus faserverstärkten Kunststoffen. Kunststoffe Automotive Powertrain, München, November 2011

Hopmann, Ch.; Michaeli, W.; Bastian, R.: Spaltimprägnierverfahren – Herstellung komplexer FVK-Bauteile in kurzen Zykluszeiten. GAK - Gummi, Fasern, Kunststoffe 65 (2012) 02, S. 120-124

Hopmann, Ch.; Bastian, R.: Neue Werkzeugtechnologien für die FVK-Serienproduktion. Tagungsunter­lagen 26. Internationales Kunststofftechnisches Kolloquium des IKV, Aachen, März 2012

Hopmann, Ch.; Bastian, R.: Realisierung einer FVK-Serienproduktion mittels neuartiger Werkzeugtechnik. Lightweight Design (2012) 6, S. 57-62

In sub-project 8, „forming and curing“, the impregnated preforms from sub-project 4, „PU spray impregnation“, and sub-project 5, „high-pressure impregnation“, were formed into components and cured. Therefore, this sub-project is at the end of the process chains. Thanks to sophisticated mould concepts and to an optimized process of forming and curing, the scientists were able to achieve the high component qualities required. 

Publications

Michaeli, W.; Winkelmann, L.; Pöhler, M.; Wessels, J.: New process technology for high volume production of composites. Journal of Polymer Engineering, 31 (2011) 1, S. 63-68

Hopmann, Ch.; Wessels, J.: New Compression Molding Technology for Forming and Curing of Pre-impregnated Textile Preforms. SAMPE 2012 Conference, Baltimore, Maryland, USA, Mai 2012

Hopmann, Ch.; Karatzias, C.: New compression molding technology for high volume production of continuous fiber reinforced structural composites. 28th Annual Meeting of the Polymer Processing Society, Pattaya, Thailand, Dezember 2012

Michaeli, W.; Fischer, K.; Bastian, R.; Winkelmann, L.; Wessels, J: Prozessketten für FVK in der Großserie. 25. Internationales Kunststofftechnischen Kolloquium des IKV. Aachen, März 2010

Michaeli, W.; Wessels, J.: Formgebung und Vernetzung flüssig imprägnierter Preforms im Pressverfahren. Zukunftsgespräche Leichtbau: Neue Großserienverfahren – Neue Möglichkeiten für Composites, Institut für Kunststoffverarbeitung, Aachen, Juli 2010

Michaeli, W.; Winkelmann, L.; Pöhler, M.; Wessels, J.; Bastian, R.: Neue Großserienverfahren für Composites. Plastverarbeiter, 61 (2010) 12, S. 22-23

Karatzias, C.: Neue Presstechnologie zur großserientauglichen Konsolidierung imprägnierter Preforms. Abschlusskolloquium der Forschergruppe 860, Aachen, Dezember 2012

Hopmann, Ch.; Bastian, R.; Karatzias, C.; Greb, C.; Ozolin, B.: Faserverstärkte Kunststoffe – tauglich für die Großserie. ATZ Automobiltechnische Zeitschrift, 115 (2013) 4, S. 262-266

Dipl.-Wirt.-Ing. Arne Böttcher

Head of department Composites and Polyurethane Technology +49 24180-923884 arne.boettcher@ikv.rwth-aachen.de

Further Information

As part of the FOR 860 research group, scientists of IKV, ITA and Fraunhofer IPT are involved in several sub-projects. For more information on all projects, go to the FOR 860 website.

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