JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008 - 41

Prepreg Cost-effective high-performance solutions for automotive body panels The growth of advanced composites in the manufacture of automotive bodywork components is limited by a number of factors such as labour-intensive lay-up, trimming and finishing processes, long processing times, and high raw material costs. Delta-Tech has developed a range of prepreg materials that reduce the cutting and trimming work while improving impact behaviour and other safety aspects. Kordo™ − Net-shape components directly off-the-mould* PAOLO NIERI, PRESIDENT, DELTA-TECH SPA he use of composites in the fabrication of automotive body panels is limited by a number of factors associated with open mould processes, while recent developments in RTM and vacuum infusion have opened new opportunities allowing lower temperature processing, less labour-intensive layup and faster tool turnover. Yet these alternative technologies do not completely resolve all problems, or may require a massive production effort in order to make up for the higher development and tooling costs. Another issue related to the use of composite materials in automotive bodywork components is their poor ability to dissipate impact energy. Solid panels that have the required flexural stiffness to remain stable in the presence of aerodynamic forces often exhibit stiff and elastic behaviour in case of an impact. If the impact is against a human body, it may cause serious personal injuries. To improve this behaviour, several types of micro-sandwich configurations have been developed, where a tough woven or non-woven core, often made of polyester or aramid fibre, is placed between skins made of woven carbon or glass fibre. In other cases, the core is made of a tough syntactic resin layer. Over the past few years, Delta-Tech has been committed to providing cost-effective high-performance solutions to the automotive industry using prepreg technology. In particular, Delta-Tech has focused on reducing the cutting and trimming work for parts made in open moulds, reducing the cost of bodywork lay-ups and improving the impact behaviour and other safety aspects related to the use of composite materials in automotive applications. T A new technology developed by Delta-Tech now makes it possible manufacturing components in open moulds with no need for subsequent cutting and trimming, by forming a round edge directly in the mould. Kordo™ is an impregnated pre-formed edging ribbon which can be laid around the part contour during the lay-up process. This is very easily done, due to the very soft and pliable nature of the ribbon, enabling bending even around a complex part contour. Kordo™ is made of a prepreg strip folded around a soft polyester braid in such a way that the two strip edges are then matched and stuck together. The resulting preform (see Figure 1) is supplied in 20-50 metre long coils. During the lay-up process, the thick side of Kordo™ is pointed outwards, while the thin side overlaps with the panel plies. It must be noted that a little dam with the required edge profile Fig. 1: Kordo™. needs to be built in the mould in order to precisely place the ribbon during lay-up and get the right shape in the final part. This way, the edge shape is controlled only up to the vertical sidewall. If a completely round shape is required, a semi-rigid caul pad can be used. In this case, a positioning groove must be created on the tool in order to precisely match tool and caul pad. Kordo™ can be made of different fibres such as carbon or glass, and is available in different thicknesses. The typical edge diameter is 5 mm or 3 mm. Kordo™ is impregnated with matrix systems that are designed to match with the wide range of Delta-Preg prepreg systems, specifically addressed to the automotive market. Figure 2 shows a typical application for the bodywork components of the X-bow, a high-performance car from the No45 November-December 2008 / jec composites magazine

JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008