Preform-engineering: applied sewing technologies to incorporate part and process functions into dry textile reinforcements

The manufacturing of final part shaped, process and stress adapted reinforcements for fibre-reinforced-polymer-composites (FRPC) is the key element for highly efficient liquid composite moulding (LCM) processes [Beckwith SW. RTM, VARTM, and SCRIMP processing infusin technologies. ‘SAMPE 44th ISSE/SAMPE ‘99’’, Long Beach, CA, 24 May. Murray, Utah; Beckwith Technology Group; 1999; Carter J, Lo Faro C. Beyond mechanical performance: product design for low cost manufacturing of composites for aerospace applications. In: Stephan A, editor. Proceedings of the 1st Stade Composite Colloquium, Stade, Germany, 7–8 September; 2000]. Based on the application of fully automated stitching or sewing technologies for the realisation of exactly shaped “Tailored Reinforcements (TR)”, the integration of processing aspects, load bearing structures (e.g. bighead® or other inserts), as well as quality management elements is realised. Integrating, or “stitching-in”, metallic inserts, results show the strong potential concerning the processing advantages and the strong bonding strength benefits. In particular, pull-out tests of “through-the-thickness” reinforced insert interfaces between metallic element and FRPC body was improved by the factor 4. The shear-strength of the interface between substrate (FRPC body) and insert showed a similar behaviour. Preparing the base laminate for the adaptation of inserts or tool mounted spacers is found to be the essential issue [Composites Part A, 29A (1998) 693]. The TR process addresses these issues besides additional FRP-manufacturing matters. The relationship between preform manufacturing and FRP-processing is given by understanding sewing parameters and their interactions with the used reinforcement. By this means, for example, the compaction of FRPC reinforcement due to stitching parameters is quantified. Based on the information that is generated throughout the TR-processing (regarding the quality and automation level of the perform), a QM system can be introduced to monitor the preform quality on-line. Tracing this acquired data, information can then be forwarded to the LCM process as well as to the design of the FRPC part. After all, an integrated performing process can be established.