Fabrication of metal injection moulds by Additive Manufacturing (AM) allows incorporation of internal geometries such as conformal channels for part cooling. Improved heat transfer during the injection moulding cooling stage reduces cycle time and improves quality due to more uniform and effective heat removal. As an alternative to channels, lattice structures employed for material and weight savings in the AM mould are investigated for simultaneous cooling of the injection mould core and cavity. In this study, four lattices including Cubic, Body-Centred Cubic, Triply Periodic Minimal Surface-based Solid Diamond, and Sheet Diamond are simulated thermohydraulically in ANSYS Fluent. Lattices of total size 20×10×10 mm with porosities from 50% to 90% are analysed for Reynolds numbers between 1,250 to 10,000. Nusselt numbers and friction factors are presented, while a trade-off between both is examined using the Performance Evaluation Criteria (PEC).

Compared to an open channel, all lattices studied provided more uniform cooling and also increased the Nusselt number. Decreasing lattice porosity, increased Nusselt number by 11 times and heat flux uniformity index by 18.74% for a Body-Centred Cubic lattice of 50% porosity exposed to a Re of 2,500. Such enhancement was attributed to greater wetted surface area, increased fluid velocity and turbulence intensity within the lattice, thinner boundary layers, and consequently lower thermal resistance. However, pressure loss increased by increasing Re and lowering lattice porosities. These results indicate the potential of lattices, to deliver enhanced thermal control in injection moulds while also aiding structural, weight and material sustainability considerations.