Determination of the interfacial heat transfer coefficient at the metal-sand mold interface in low pressure sand casting

The interfacial heat transfer coefficient (IHTC) at the metal-sand mold interface was determined by applying a nonlinear inverse estimation method during the low pressure sand casting (LPSC) process. Experiments were conducted using plate shape castings with different thicknesses for both ZL205A and ZL114A aluminum alloys. A specific temperature sensor unit was developed to measure accurately the temperature evolution inside the sand mold, based on which the IHTC was estimated. Results showed that the time-dependent IHTC during the LPSC mainly comprised two stages, i.e., rapid increasing stage and maintain stage, and the second stage could be further divided into two parts based on the plate thickness. Besides, the IHTC was found to be also highly dependent on the casting material, especially the maximum value. Further analysis also revealed that the estimation accuracy of the inverse method was increased by 50% if the temperature dependence of the thermo-physical parameters was considered, rather than normally constant treatment or simple linear interpolation versus temperature.