High-speed 3D printing with enhanced isotropic strength using post core casting

Abstract

Fused filament fabrication(FFF) is a technology that can manufacture arbitrary three-dimensional shapes bycontinuously stacking planar polymer layers on a continuous filament-like polymer material with a freely transferablenozzle. It can be manufactured and is suitable for small quantity production of various kinds. However, FFF fabricatedfeatures cannot be used as an engineering material due to a decrease in strength between polymer layers during theproduction process, and has a disadvantage in that the production speed is lower than that of injection molding. In thispaper, a new process for manufacturing a isotropic, high-strength structural material was studied by molding a hollowshape using FFF technique, then filling the inside with an epoxy resin and curing it. By using the surface etching methodusing acetone to reduce the periodic interlayer roughness inside the shell composed of a FFF fabricated polymer, theproblem of remarkably lowering the layer direction strength of the composite material due to the stress concentration ofthe epoxy interior material was solved. It was experimentally verified that the composite material manufactured by thisprocess follows the theory of the rule of mixtures, and it was shown that anisotropy can be removed through the selectionof an appropriate epoxy resin. In addition, in this study, the effect of acetone solvent treatment on the adhesion interfacewas experimentally verified by testing the mode 2 fracture toughness between the outer shell and the interior material, andthe debonding phenomenon of the composite material under uniaxial load was theoretically analyzed.