The mold filling behavior in lost foam casting (LFC) is known to be quite different from that of gravity sand casting because of the existence of a gas layer between the melt and foam. However, some phenomena are still not clear about the mold filling and pattern decomposition. In this work, experiments were performed to examine the mold filling and gas decomposition behaviors in the LFC of aluminum by using conventional experimental methods and a new one. It was found that the gas pressure varies within 20 % from the value of the melt head, and the melt velocity increases with decreasing coating thickness and melt head. Further, the vibration of the gas pressure was found by using a microphone inserted in the sand mold and a gas pressure sensor. The vibration phenomena can be explained well by a mass-spring model, where the melt behaves as mass and the gas layer behaves as spring.
