Interlayer healing mechanism of multipath deposition 3D printing models and interlayer strength regulation method

Abstract

Extrusion-based 3D printing technology has gained widespread application in industrial production due to its low cost, high customizability, and excellent material compatibility. However, during the molding process of extrusion-based additive manufacturing, the influence of healing temperature, interlayer pressure, and insufficient healing time leads to inadequate healing behavior between deposition paths, making it challenging to maintain mechanical strength consistency in the deposition direction with other directions. Considering the interlayer healing theory of polymers, this study proposes a 3D printing strategy based on material extrusion, achieving enhanced interlayer mechanical properties through topologically optimized nozzle structures. Firstly, based on the rheological behavior of consumables at the nozzle of the fused filament fabrication (FFF) extruder, a molten fluid deposition model is established, and the nozzle cross-sectional shapes for different target extruded filament shapes are obtained through inverse extrusion prediction techniques. On this basis, combined with the interlayer healing strength theory of FFF extrusion molding, the relationship between extruded filament geometry, intimate contact, and contact pressure is analyzed to achieve the goal of improving the interlayer tensile strength of molded parts. A highly compatible, real-time monitorable 3D printing platform was established, and standard tensile specimens of different extruded filaments were prepared and their tensile properties measured to validate the correctness of the multi-path deposition model. Results showed that compared to traditional nozzles, the interlayer tensile strength of parts manufactured using square nozzles increased by approximately 37.8 %. This technology provides a new paradigm for extrusion-based additive manufacturing in the 3D printing of high-performance mechanical structures and has potential implications in fields such as aerospace and automotive components.