Numerical Analysis of Flat Corners Cooling of 3D-Printed High-Pressure Tools for Aluminium Casting

Mould cooling is regarded as the biggest influence in production cost of injection moulding due to the fact it contributes to the largest percentage of cycle time. Conventional manufacturing methods has always been the biggest constraint in mould cooling design where the solution is only limited to circular straight-drilled channels. Conformal cooling is an alternative to conventional cooling where 3D printed moulds have cooling channels shaped in the same outline as the cavity. Despite the considerable number of literatures in conformal cooling for injection moulding, limited work has been carried out in cooling for corner regions where the volume of cast to surface area of interface vary significantly. Moreover, the coolant may experience flow separation and subcooled boiling condition. In this study the effects of the main independent parameters for cooling corners of 3D printed H13 steel mould for aluminium casting are investigated. The heat flux and the interface temperature have been identified using a conjugate heat transfer 3-D CFD model. The model is developed based on steady conditions which are validated using experimental data. The spatial temperature distribution at the cast-mould interface has been evaluated and presented. A generic equation has then been developed using multiple linear regression method to calculate the interface temperature and its standard deviation as a function of the main parameters which include depth, pitch, diameter and coolant flow velocity. The equation can be used as a guide for cooling channel design without a need for running multiple CFD simulations. The results are compared against a flat plate geometry to identify the differences between cooling channels with 90-degree corner bend and straight channel flow for mould cooling. The results showed also that the shape factor equation available in literature cannot be used to fully describe the orientation and positioning of the channel relative to the cast interface without applying a correction factor.