Predicting heat extraction due to boiling in the cooling channels during the pressure die casting process

The effect of boiling on the rate of heat extraction by cooling channels em ployed in pressure die casting dies is investigated. The cooling effect of the channels is simulated using a model that accounts for subcooled nucleat e boiling and transitional film boiling as well as forced convection. The b oiling model provides a continuous relationship between the rate of heat tr ansfer and temperature, and can be applied to surfaces where forced convect ion, subcooled nucleate boiling and transitional film boiling are taking pl ace in close proximity. The effects of physical parameters such as flow vel ocity, degree of subcooling, system pressure and bulk temperature are taken into account. Experimental results are obtained using a rig that simulates the pressure die casting process. The results are compared with the model predictions and are found to show good agreement. Instrumented field tests, on an industrial die casting machine, are also reported. These tests show the beneficial effects of boiling heat transfer in the pressure die casting process, including a 75 per cent increase in the production rate for the t est component.