Design and Implementation of a Novel Fiber Deposition System to Enable Laser Sintering of Chopped Fiber Reinforced Polymers

In this research, the design and implementation of a novel chopped fiber deposition system for the laser sintering (LS) process is discussed. The system allows deposition of chopped fibers with different lengths and of multiple fiber types in a commercial LS machine. A weight percentage of 5% (2 vol%) glass fibers can be implemented without disturbing the LS process. LS specimens both with and without fibers can be produced during the same job as the setup only deposits fibers on half the powder bed. This is to reach an in-depth understanding of the influence of fibers on the produced specimens as the comparison can be made with the matrix material built in the same job. The setup was developed to answer the increasing demand for additively manufactured polymer composites with optimized mechanical properties currently manifesting in industries such as aerospace, biomedical, and automotive. To reach successful stress transfer from fiber to polymer, fibers need to have a certain critical length dependent on the combination of fiber and matrix material. For most material combinations, this length is longer than what is obtained with the fillers reported in literature. The development of the deposition system successfully allows the deposition of chopped fibers with longer lengths (to reach successful stress transfer) during the LS process, overcoming previously reported difficulties. The setup consists of six main components and can be connected to the recoating roller or blade present in every LS machine. With a test sieve, the vibrating system and a four-blade mixer are the most important for the functioning of the system. After preliminary testing, a profound optimization of the setup was conducted after which LS specimens with chopped fibers were successfully produced. X-ray computed tomography imaging of the produced specimens with fibers, showed a successful integration of chopped fibers in different random directions throughout the layers.