Study on Contact Structures and Joint Strength of Injection Molding Dual‐Polymer Parts Utilizing <scp>3D</scp> Printing Insert

ABSTRACT 3D printing offers flexibility in geometric design, but it is inferior to injection molding in terms of strength. In this study, the joint strength of 3D printing and injection molding parts is investigated. A series of distinct insert contact architectures were manufactured to offer design freedom with polylactic acid (PLA), acrylonitrile‐butadiene‐styrene (ABS), and thermoplastic polyurethane (TPU). Injection molding parts were manufactured as substrates using polymethyl methacrylate (PMMA). The melt flow process was simulated via finite element analysis (FEA), along with static simulations of uniaxial tension and three‐point flexural tests. Experimental validation through quasi‐static uniaxial tensile and flexural tests quantitatively assessed the tensile and flexural properties of the dissimilar material joints under varying contact geometries. The results indicate that PLA–PMMA (P–P) and TPU–PMMA (T–P) achieve optimal tensile performance with Structure 3, whereas ABS–PMMA (A–P) exhibits superior tensile properties under Structure 2. In terms of flexural performance, both P–P and A‐P attained optimum results with Structure 3. The FEA simulation accurately predicted the critical sections, and the results of tensile and flexural strength predictions were consistent with the experimental results, with an average error of 15.16%, indicating a reasonable error range.