Hybrid fused deposition modelling-investment casting for manufacturing Al 7075 truncated octahedron lattice structures

This study proposes a hybrid manufacturing route combining Fused Deposition Modeling (FDM) and investment casting to produce Al 7075 lattice structures with truncated octahedral geometry, supporting SDG 9 on industry, innovation, and infrastructure. Polylactic-acid-based composite filaments were used to fabricate sacrificial patterns, followed by thermal removal, mold sintering, and metal casting. The effect of strut diameter (4.6–5.0 mm) on fabrication, microstructure, and hardness was evaluated. Vacuum-assisted casting achieved the highest filling efficiency and minimized defects, enabling complete formation at 5.0 mm. It also reduced porosity and improved solidification uniformity. Increasing strut diameter enlarged grain size (up to 301 µm) while decreasing hardness (to 78.3 HV), confirming strong geometry–property relationships.