Pressure measurement and some observation in lost foam casting

摘要

Experiments are being conduced in a photography technique to examine flow of aluminum, cast iron and steel into the molds. The purpose is to observe some parameters such as gas gap length, foam decomposition products, metal front and mold filling time in lost foam casting of aluminum, cast iron and steel. Foam-metal interface reactions and gas evolution have been observed during mold filling. The results indicate that the metal pouring temperature and foam density and coating layer thickness affect mold filling time. In the steel lost foam casting, the gas gap length and gaseous products volume and the mold filling time are significantly larger than the cast iron. In both the cast iron and the steel lost foam casting, the foam pattern escapes from the mold mainly in the form of gases but in the aluminum lost foam casting foam pattern mainly decomposes into liquid polystyrene and no gas gap layer has been observed. Results of back pressure measurements show that with increasing foam density and melt head (sprue height) gas pressure increased significantly.