Hybrid manufacturing of mixed-material bilayer parts via injection molding and material extrusion three-dimensional printing

In this paper, a hybrid manufacturing method combining the advantages of injection molding (IM) in terms of manufacturing efficiency and high precision with those of three-dimensional printing (3DP) in terms of minimum waste and a high degree of freedom is described to produce mixed-material bilayer tensile specimens. 3DP was first utilized to fabricate polylactic acid substrates with four varied geometries and two infill densities and an overmolding technique was employed to finish the manufacture using acrylonitrile butadiene styrene under two IM pressure. analysis of variance and scanning electron microscopy (SEM) were used to investigate the tensile properties and microstructures of the samples. The results showed that a greater tensile performance could be found in those specimens with greater infill density. Lower-pressure overmolded specimens performed better than those with higher IM pressure. In addition, female joints outperformed male joints in the tensile performances of finished specimens. This study optimized the parameters for this hybrid manufacturing process for building mixed-material parts and has potential applications in manufacturing, particularly manufacturing as a service.