Integrated hybrid shell–backfilled strategy using blended photopolymers for cost-efficient vat photopolymerization injection mold inserts

Purpose Owing to scalability and cost barriers in vat photopolymerization rapid tooling, this paper aims to investigate a framework for fabricating cost-efficient mould inserts using liquid crystal display-based masked stereolithography (LCD-MSLA) systems and blended open-market photopolymers, accounting for anisotropy, thermo-mechanical robustness and separation–force constraints. Design/methodology/approach A material–architecture–simulation–experimental methodology was developed. A high-temperature photopolymer was blended with a toughening component to tune stiffness within manufacturable limits. Compression testing quantified anisotropy and identified elastic and strength parameters for finite element (FE) models. Rheological simulations defined pressure and loading conditions. A hybrid shell–backfilled insert architecture balanced stiffness and manufacturability in bottom-up MSLA printing. Inserts were validated by moulding trials. Findings Compression testing revealed build-direction anisotropy, with the Z-oriented configuration showing a Young’s modulus of 1892 MPa, yield stress of 45.24 MPa and fracture stress of 84.49 MPa. Rheological simulations predicted filling and packing conditions consistent with trials using mineral-filled polypropylene. Validation demonstrated stable moulding over 40 cycles, cycle time of 69.27 s and a peak injection pressure of 44.2 MPa. FE analyses under worst-case loading predicted stresses below the fracture limit, with no observable structural degradation. Practical implications The results are relevant to industry, designers and researchers, demonstrating that cost-efficient LCD-MSLA platforms combined with open-market photopolymers can produce reliable short-run injection mould inserts for prototyping and low-volume production without high-cost materials or specialised machinery. This helps bridge an industrial gap in rapid tooling accessibility. Originality/value To the best of the authors’ knowledge, this is among the first studies to investigate cost-efficient LCD-MSLA-fabricated injection mould inserts for relatively large tooling geometries using blended open-market photopolymers under coupled manufacturability, thermo-mechanical and structural constraints.