Applying material jetting to produce prototype injection moulds from medical grade and conventional photopolymers

Additive manufacturing has recently emerged as a viable approach for producing prototype injection moulds for low-volume manufacturing. PolyJet-printed photopolymer inserts offer rapid lead times and cost efficiency, but their limited thermal resistance, low thermal conductivity, and tendency to creep are fundamental constraints on mould lifetime and process stability. In this study, the suitability of the MED615RGD biocompatible photopolymer for injection mould tooling was investigated and its performance was compared to the widely used VeroWhite photopolymer resin. Comprehensive thermal and mechanical characterization was conducted, including dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), heat deflection temperature (HDT) and Shore D hardness testing, creep analysis, and 3D optical scanning. These tests help to evaluate the fundamental thermal and mechanical properties of the mould, which govern its durability. After the material tests, mould inserts were printed from VeroWhite and MED615RGD. The inserts were subsequently built into a custom-designed, experimental injection mould, equipped with strain gauges and an embedded thermocouple, which enables real-time monitoring of deformation and thermal loads during the injection moulding tests. The experimental results showed that MED615RGD exhibits a higher glass transition temperature (T g = 78.3 °C) and improved stiffness compared to VeroWhite (T g = 70.5 °C), while maintaining similar hardness. During injection moulding, both materials suffered from progressive heat accumulation due to low conductivity, resulting in dimensional deviations and eventual edge failure. Tool degradation began in the 40–50 cycle range, consistent with previously reported PolyJet-based tooling lifetimes. The findings confirm that MED615RGD is suitable for rapid tooling applications where short manufacturing cycles, dimensional stability, and design iteration speed are the primary objectives. In this study, performance limitations, degradation mechanisms and practical process window recommendations are discussed for future industrial use of photopolymer rapid tooling.