Simplified CFD Model for Assessing the Cooling Channel Design in 3D Printed High-Pressure Tools for Aluminium Alloy Casting

Additive manufacturing (AM) provides significant geometric design freedom for the cooling of high pressure die casting (HPDC) tools. Designing cooling channels that can achieve a uniform temperature throughout the tool-cast interface during the moulding process can limit part warping and sink marks, internal part stresses, and increase tool life. However, the design of the embedded cooling channels requires high computational resources to model the heat transfer process for the cast, mould, and coolant from the moment aluminium is injected into the cavity until the injection for the next cycle. To enable the examination of the effect of various parameters, a simplified 3-D CFD conjugate heat transfer model is introduced by considering the experimental observations. The model decouples the cast part from the mould. A volumetric heat source term is added to the energy equation to represent the solidification energy, and accordingly the heat flux is evaluated on its surface that has been set to a uniform temperature. The heat flux is then compared with that obtained from the mould surface for a specific cooling channel layout. With this approach it is possible for the designer to rapidly assess the cooling system without incurring significant computational cost. The model reveals the undercooled and overcooled regions, which are then matched with the observational results obtained by analysing the tools and the aluminium cast surface. The results prove that the model can be employed to develop a baseline design of the cooling channel network for a complex geometry before applying an optimisation technique. It can also be useful for assessing the effect of various parameters, and to carry out a parametric sensitivity study with limited computational cost. The limitations of the model are evaluated and discussed in this work.