A CORRELATION TO DESCRIBE INTERFACIAL HEAT-TRANSFER DURING SOLIDIFICATION SIMULATION AND ITS USE IN THE OPTIMAL FEEDING DESIGN OF CASTINGS

It is known from experimental data that for pure aluminum castings man ufactured via the gravity die casting process, the interfacial heat-tr ansfer coefficient can vary in the range 500 to 16,000 W/m(2) K. These coefficients are of significant importance for the numerical simulati on of the solidification process. The experimentally determined variat ion of interfacial heat-transfer coefficients with respect to time has been recalculated to highlight the variation with respect to casting temperature at the interface. This variation was observed to be of an exponential nature. Also, the pattern of variation was found to be sim ilar in all the experimental results. It has been found that all these patterns of interfacial heat-transfer coefficient variation can be ma tched by a unique equation that has been proposed as a correlation to model the metal-mold interfacial heat transfer. The benefit of this co rrelation is in its ability to approximate the combined effects of geo metry variation. insulation, chills, die coatings, air gap formation, etc. during the numerical simulation and its use in the optimal design of heat transfer at the metal-mold interface.