The market for glass fiber reinforced polymer composites (GFRPC) has been showing stable growth for years, with thermoplastic composites as main growth drivers. In order to make better use of the mechanical properties of the reinforcing fibers, unidirectional fiber structures with load optimized design are necessary. For the manufacturing of unidirectional fiber structures the tape placement process is ideally suited. However, these fully impregnated tapes are only available in certain fiber-polymer combinations, which limit the applicability of this process. The dry fiber placement (DFP) is a modified tape laying process, which draws back on non-impregnated rovings to manufacture load-related preforms for Liquid Composite Molding processes.
A new manufacturing process developed at IVW combines the advantages of thermoplastic tape placement with the DFP for production of continuous fiber-reinforced thermoplastics. Thermoplastic powder towpregs (with complete polymer content for the final part) are produced on roving-level and processed by fiber placement to pre-impregnated preforms. During the processing of powder towpregs, the thermoplastic powder serves as binder (similar to DFP). Subsequently, the preforms are fully impregnated and consolidated by a variothermal pressing process.
Initial test series covering the whole process chain were carried out and analyzed at IVW. The varied parameters for fiber placement are placement-speed, temperature, and the compaction force of the consolidation role. In the subsequent pressing process, pressure and time as well as processing temperature are varied. The aim is to achieve a comprehensive process optimization in terms of best component quality with short cycle times considering correlations and influences between these two processes.
Continuous Fiber-reinforced Thermoplastics, Dry Fiber Placement, Tape Placement, Variothermal Processing, GFRPC