Fibers are one of the most important reinforcement materials for polymers. Combining fibers with polymer resins significantly increases the mechanical properties of the polymer material. Due to their relatively low weight, fiber-reinforced polymers are often used in the design of lightweight parts typically found in the automotive or airspace industry.
While fiber-reinforced polymers traditionally consist of thermosets, a trend towards the use of thermoplastic matrices has emerged in industry. Due to their chemical structure, the latter class of polymers becomes moldable at certain elevated temperatures and reform upon cooling. For the production process, these characteristics bring about a number of advantages including a higher degree of automation and the potential of material recycling.
In the machine hall “Smart Extrusion” of the LIT-Factory, thermoplastic tapes reinforced with unidirectional-oriented (UD) continuous fibers are produced. A haul-off unit located at the end of the process line pulls continuous fiber rovings (e.g., glass or carbon fibers) from creels that are placed on a strand. Before entering the extrusion die, the rovings are threaded through a spreading unit to force the filaments to distribute uniformly over the width. The rovings are then pulled through an extrusion die, where impregnation with a thermoplastic polymer melt (e.g., polypropylene or polycarbonate) and shaping take place. In the downstream processing steps, the fiber-reinforced thermoplastic tape is calibrated, cooled down, and winded.
DI Dr. Christian Marschik knows more about UD Tape Extrusion