The use of fiber-reinforced thermoplastic composites plays an integral role in the challenging but highly rewarding task of replacing various costly metal fabrication techniques such as Die Casting. Long Fibre Thermoplastic (LFT) composites coupled with best moulding practices and parts engineering can close the performance gap between the more traditional Short Fibre Thermoplastic (SFT) composites and their metal counterparts.
Complex part geometries make continuous fibre reinforcement or placement difficult or near impossible in all but simple, rectilinear, part geometries. Therefore, the reinforcing fibres used are chopped and randomly distributed in the polymer matrix to fill the part shape. However, these SFT’s offer only a fraction of the strength of continuous reinforcement. LFT composites are a means to approach the original promise of continuous fiber-reinforcement.
Since fibre-reinforcement is inherently anisotropic, fibre-orientation must be tailored to match load direction. Furthermore, the process of LFT injection moulding differs from standard SFT techniques and, if considered correctly, allows LFT composites to reach their potential. Several examples of real parts and designs in various industrial sectors are shared to highlight these considerations. Since manufacturability is often the first and last concern, the successful injection-moulding of LFT composite parts is described, including modern tools for part and mold design.