A project from Ips Intelligent Pelletizing Solutions, conducted in collaboration with Cetex Institute for Textile and Processing Machines at the Technical University of Chemnitz, has resulted in the development of a pelletising system offering a more efficient manufacturing technology for long-fibre reinforced polymer pellets.
Compared with short-fibre reinforced plastics, components made of long-fibre reinforced thermoplastics have a much greater impact/notched bar impact strength, significantly higher material strength and outstanding rigidity with less material used. These materials offer promising design possibilities for the lightweight engineering of materials and structures, said Ips.
“Applications for which metals have mainly been used before can now be realised at lower cost and with less impact on resources by long-fibre reinforced thermoplastics,” said managing director Simon Weis, who is responsible for the LFT project at Ips.
The Ips system LFT HP makes use of the pultrusion or strand pulling method. An 8-strand pilot system that is also available for customer trials is currently in operation. The system is able to produce a wide range of materials with different fibre reinforcement levels, defined pellet length sand different polymers. Fibre - which might be glass, carbon, aramid or hybrid combinations - contents of between 30 and 60 wt% are possible, according to Weis, and throughputs of up to 1,000 kg/h are possible. All common technical polymers can be used as melts. The cut length of the strands can vary between 6 – 25 mm. The fibre lengths correspond exactly to the cut length of the pellets.
The system has a modular design and starts with the controlled unwinding of the rovings to avoid twisting. This is followed by their impregnation with polymer melt and subsequent post-forming and shaping. Depending on the polymer type, the LFT strands are cooled by water. There is a strand cooling trough with integrated process water system available as an option for this purpose.
All the modules of the Ips LFT system are controlled via a central user interface. This covers everything from draw-off speed through extruder throughput to cut length of the pellets. All components have variable control.