The VOF (Volume of Fluid) method is adopted by most of the software used for the calculation of the interface, which consists of molten metal and air, during mold filling simulation. Since conventional cell volume fraction (F value) approaches apply the DA (Donor-Acceptor) procedure for the transport of fluid-segments, the interface slope cannot be transported with sufficient accuracy. On the other hand, the MARS (Multi-interface Advection and Reconstruction Solver) method developed by Kunugi has great advantages in terms of the accuracy to estimate the interface shape and quantity of advection. While the original software TopCAST™ applies the Porous-Media element, the MARS method simulates the mold filling behavior of thin-thickness castings. In mold filling analysis applying MARS, the capture shape of the free surface was found to improve during mold filling. It was also shown that it is very important to consider the surface tension in order to obtain reasonably accurate results. Furthermore, simulation performance such as CPU time and memory required were sufficient, confirming that the MARS method has adequate accuracy and functions for mold filling simulation.

  In zinc alloy die casting, soldering reactions caused by the fusion of the die-surface are, a serious problem in the manufacturing process because they lead to reduced in production efficiency. It is very important to clarify the mechanism of soldering reactions from the physical and chemical perspectives in order to prevent or reduce zinc soldering on the die surface. In this study, experiments to observe the mechanism of soldering reactions were performed using an actual die casting machine. Transmission Electron Microscope (TEM) observation and Energy Dispersed Spectroscopy (EDS) analyses were performed to investigate the interface between the die material and molten zinc alloy and to observe the mechanism of soldering reactions.

  The mechanical properties of hypo-eutectic Al-Si alloys are affected by the eutectic structure. It is well known that the eutectic structure forms coarse plate shape when the quantity of P is large. For this reason, a technique for manufacturing hypo-eutectic Al-Si alloy containing a small quantity of P is being developed. Since molten metal treatments such as de-gassing, de-oxidation, modification treatment etc. are carried out in the manufacturing process, we performed analysis of the pre-casting process. It was found that, according to this technique, the quantity of P is as small as 10ppm or less, and it is possible to produce molten metal with relatively small quantity of gas and oxide.