JEC COMPOSITES MAGAZINE - Issue #76 - October/November 2012 - 74

cost effectiveness

Cost-effective preform production for complex FRP structures
The production of highly integrated textile preforms for fibre-reinforced plastic (FRP) components accounts for up to 40% of the overall component costs as state-of-the-art preforming processes are predominantly based on manual and semi-automated operations. The combination of innovative single step and multi-step preforming processes is a viable approach for cost-effective preform production.

Fig. 1: Cost allocation of a RTM-manufactured part [2]

By
Christoph Greb, Head of research group 3D-Preforming, , Andreas Schnabel, Head of research group 2D-Preforming, Felix Kruse, Dipl.-Ing., Markus Linke, Head of division Composites, Thomas Gries, Head of Institut für Textiltechnik Institut für Textiltechnik (ITA) RWTH Aachen University

The combination of innovative single step and multi-step preforming processes is a viable approach developed by the Institut fuer Textiltechnik of RWTH Aachen University (ITA) in Germany for cost-effective preform production. In single-step preforming, non-crimp fabrics (NCF) with locally-adjusted properties are produced. These properties include local reinforcement and locally-adjusted drapability. Drapability can be defined as the ability of semi-finished laminar material to adapt onto curved three-dimensional surfaces [3]. These textile structures are then converted into near-net shape textile preforms in a sequence of automated processing steps, called multi-step preforming. A preform is defined as a textile fabric used to produce a finished part with a predefined amount of fibres, fibre orientation and shape [4]. Hence, both cycle time and production costs can be reduced [5]. Figure 2 shows a comparison of a state-of-the-art preforming process and the single-step/multistep preforming process. When producing three-dimensional FRP components, textile structures need to be draped. Current non-crimp fabrics have a constant drapability in the direction of production, which makes processing difficult. For easy handling, large, flat surfaces require high bending stiffness, while small radii demand a low bending stiffness of the textile. Therefore, the ITA has developed and implemented a technology to locally adapt the warpknitting pattern and thus the local drapability of NCF during production. Furthermore, enhanced cutting, joining and handling technologies have been integrated in the automated preforming processes. The combination of these technologies promises to improve the production of near-net shape textile preforms in terms of cycle times and cost per piece. The paper focuses on the requirements, development and

lthough the market for composite materials, particularly fibre-reinforced plastics (FRP), is growing, high costs and cycle times currently restrain the use of FRP parts in serial production [1]. The production of highly integrated textile preforms for (FRP) components accounts for up to 40% of the overall component costs as state-of-the-art preforming processes are predominantly based on manual and semi-automated operations [2]. Figure 1 shows a typical cost allocation for a Resin Transfer Moulding (RTM)-manufactured part, including preforming.

74 jec composites magazine / No76 October - November 2012

JEC COMPOSITES MAGAZINE - Issue #76 - October/November 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #76 - October/November 2012