Conformal cooling of aluminium flat fins using a 3-D printed water-cooled mould

The cooling phase within the high-pressure injection moulding process is critically important to produce good quality parts in minimum cycle time and to maximise the tool life. Modelling the cooling process in the mould during the casting process is very complex and required high computation resources which could be challenging especially, when examining various design parameters. In this work, a simple model has been developed based on experimental work that shows the interface temperature during the cooling process inside the mould remains almost constant until the mould is opened. Based on this observation, the heat flux generated from a generic shape of a molten aluminium alloy flat fin to achieve a uniform temperature at its outer surface is evaluated assuming steady state condition during the moulding time. A conjugate steady heat transfer model has been developed using a 3-D CFD model that utilizes RANS together with Low-Reynolds Number k- turbulence model to evaluate the cast-tool interface heat flux distribution assuming the pre-defined interface temperature. It was therefore economically possible to evaluate the effect of cooling flow velocity and channel location and layout on the cooling rate and the heat flux with a limited computation resource. The high heat flux at the corners of the fins was evaluated and effect of various fillets showed there is an optimum radius to achieve minimum average heat flux in the corner area. It was concluded that the new method can provide the necessary information for the initial design of the cooling channels for various fins thickness before a final optimization method can be implemented. The model result was in close agreement with a full transient model that includes the molten aluminium, the mould and cooling water.