JEC COMPOSITES MAGAZINE - Issue #66 - July/August 2011 - 35

Fig. 2: Component complexity against achievable performance for moulded and thermoformed components, and for the new processes

the new processes also facilitate the combination of different component properties that are not achievable using conventional manufacturing processes or which can only be achieved in several separate process steps. The excellent formability of thermoplastic composite materials, combined with tried-and-tested injection moulding technology, results in a high degree of design freedom. This, in turn, permits the integration of a host of functions within a limited space.

Closed structures / FIT-Hybrid
The FIT (fluid injection technology) Hybrid process allows the manufacture of lightweight hybrid composite tubes with integrated functional elements. This involves combining assembly injection moulding with fluid injection technology in the injection moulding process. Preheated textile preforms are first moulded using melt pressure. Then, during the same cycle, fluid injection technology (gas injection technology) is used to further mould the preforms. The subsequent heat dissipation consolidates the component. The huge degree of design freedom offered by injection moulding means that additional passive and active functional elements and modules can be integrated. Figure 3 illustrates the manufacturing principle.

In the first step, organic sheets are Fig. 3: Hollow component manufacturing using FIT-Hybrid technology [source: LKT] preheated so that they can be formed. The organic sheets are joined technology employed drives out the during the subsequent assembly thermoplastic material being used to injection moulding process, thus join the organic sheets. Thereafter, producing a sandwich preform. The the internal pressure can take effect to process involves following assembly complete the moulding of the FIT injection moulding strategies and the tube. corresponding compatibility principles to create a high-strength The results for processability and positive material bond, which is a material behaviour obtained from the necessary prerequisite for first scaled samples were transferred manufacturing a lightweight structure to a reference component (see Figure with optimal mechanical performance. 4). To a significant extent, the quality of the bond is determined by the temperature of the bond counterparts (organic sheet and injection moulding compound) at the effective interface, and the effective joining pressure. During the injection lifting process, the joining pressure is used to both bond Fig. 4: Technology transfer from sample to application [Source: LKT] and premould the organic sheets. In this process, the The design and integration of same tool is used to premould the bonding elements into the hollow profile. To form the hollow manufacturing process presented a profile, internal gas pressure is applied particular challenge for the reference using Gas Injection Technology component. These bonding elements (GIT). During the first step, the have to be capable of joining the

No66 July - August 2011 / jec composites magazine

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JEC COMPOSITES MAGAZINE - Issue #66 - July/August 2011

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