Sensorised metal AM injection mould tools for in-process monitoring of cooling performance with conventional and conformal cooling channel designs

Conformal cooling is a promising approach for reducing the cycle time and providing efficient cooling in injection moulding. Evaluating the effectiveness of the cooling performance would ideally be achieved via realtime data collection, facilitated by in-mould sensors. However, due to the limited space caused by the presence of conformal channels, embedding the sensors in optimal locations is difficult. The design flexibility of additive manufacturing (AM) for manufacturing complex internal geometries offers opportunities for unique solutions to overcome both cooling and sensorisation challenges presented by traditional manufacturing techniques. In this study, straight-drilled cooling channels are replaced with conformal cooling channels, in a mould for a complex industrial component with variable thin and thick-walled sections. The Selective Laser Sintering (SLS) technique was implemented to additively manufacture sensorised mould inserts incorporating conformal channels as well as curved channels for the targeted placement of flexible thermocouples. These sensorised mould inserts, with conformal channels, were tested in an industrial injection moulding machine, and their performance was compared to the conventional mould inserts using in-mould thermocouple data. The experiment findings revealed that the application of conformal cooling reduced the production cycle time by around 50 % and resulted in better component quality compared to conventional methods. Also, thermocouple readings confirmed temporal trends observed in earlier simulation results, indicating the elimination of hotspot regions, and achieving a more uniform temperature distribution through the use of conformal cooling. The in-mould temperature data provides real-time information on the cooling process at critical points of the component, which can be exploited for more accurate optimisation of the cycle time and ejection temperature. Moreover, the flexible thermocouples in curved channels successfully measured the mould temperature and the effect of coolant on the mould insert at two separate locations of the additively manufactured mould inserts.