Experimental investigation and numerical simulations of temperature and morphology in material extrusion additive manufacturing

Material extrusion additive manufacturing is one of the widely used rapid prototyping technology, which produces parts with complex shapes and structures by continuous deposited strands. In previous studies, the influence of process parameters on product performance was experimentally studied, while morphological evolutions of strands, particularly considering the temperature variation, were not well understood. In this study, the mesostructure formed by parallel strands during continuous non-isothermal deposition flows was comprehensively studied by numerical simulations and experimental methods. The numerical model simulated the complete process of flow, deposition, bonding, and heat transfer for the representative materials, polyether ether ketone (PEEK), and polylactic acid (PLA). The quantitative comparison of the strands cross-sectional size measured by experiments and simulations was presented, and the results were consistent. The results showed that increasing the reheating temperature can considerably improve the strand-to-strand bonding. The effects of gap distance, printing speed, and strand-to-strand distance on the mesostructures of PEEK and PLA were comprehensively investigated and compared. Additionally, the simulation and experiment results provided detailed information regarding the porosity and bonding degree, which significantly affects product performance.