SIMULATION STUDIES OF MOULD FILLING CONDITIONS WITH MOLTEN METAL IN EVAPORATIVE PATTERN TECHNOLOGY

Using available thermo-physical parameters, the paper describes the simulation studies of metal flow in mould filled with an evaporative pattern. The final properties of casting made in a lost-foam process are greatly dependent on the way by which the metal is fed to mould cavity, on the way by which gases are taken off, and also on the properties of the lost foam pattern itself, that is, on its thermophysical parameters. The gating system should be designed in a way such as to let metal flow into mould cavity with an even front surface, enabling a uniform evaporation of pattern made from, e.g., foamed polystyrene. The configuration of a gating system and the technique of metal pouring affect the rate at which the mould cavity is being filled with metal, and hence the kinetics of pattern evaporation under the molten metal effect. When lost foam patterns are used in a casting process, it is necessary to allow for the variable physico-chemical properties, which depend on pattern itself and affect the metal flow behaviour in mould cavity as well as the pattern evaporation process.

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