Integrating 3D printing and injection molding for mass customization: advancements in hybrid manufacturing

Abstract

Additive manufacturing (AM) is renowned for its ability to create complex geometries and customized products but is limited by low throughput. Conversely, injection molding (IM) excels in high-volume production but struggles with costeffective customization due to mold tooling constraints. This thesis investigates hybrid manufacturing (HM), which combines the strengths of AM and IM, as a solution for mass customization - the production of personalized products at costs comparable to mass production. The focus is on integrating fused deposition modeling (FDM), a form of AM, with IM to achieve mass customization. The study is divided into two main sections: overmolding and overprinting. In the overmolding section, FDM-fabricated preforms are integrated into the mold cavity. The study examines how various parameters, such as infill density, joint configuration, interface direction, and material choice, affect the mechanical properties of the hybrid products. The results indicate anisotropic maximum tensile strength between half-length (25.47 MPa in HL-FT 25 for Acrylonitrile Butadiene Styrene (ABS) batches and 30.11 MPa in HL-FT 75 for Polylactic Acid (PLA) batches) and half-thickness specimens (48 MPa in HT-FT 50 for ABS batches and 68.38 MPa for HTFC 75 in PLA batches) for single-material overmolding specimens. As for the dualmaterial overmolding, a worse tensile performance (46.1 MPa in 75-FT-60) in comparison to the half-thickness series for single-material ones can be found. The overprinting section explores the integration of FDM components onto injection-molded substrates. While this approach showed inferior tensile performance (47.1 MPa in 25-70-220 batch for ABS pieces and 56.3 MPa in 50-70-210 batch for PLA pieces) compared to pure IM and overmolding, it demonstrated potential benefits including reduced manufacturing costs and enhanced design flexibility. In conclusion, this thesis establishes a groundwork for future HM techniques that demand higher design flexibility and fabrication efficiency. Overmolding and iv overprinting have demonstrated their potential in producing customized products at lower costs. Future research could explore the integration of Stereolithography (SLA) for creating tailored molds with thermosetting polymers, combining higher design flexibility with cost efficiency.