Prediction of intrusive gas pores caused by resin burning in sand core for iron castings

In the production of castings, intrusive gas pore represents a kind of common defects which can lead to leakage in high gas-tightness requirement castings, such as cylinder blocks and cylinder heads for engines. It occurs due to the intrusion of gases generated during the resin burning of the sand core into castings during the casting process. Therefore, a gas generation and flow constitution model was established, in which the gas generation rate is a function of temperature and time, and the flow of gas is controlled by the gas release, conservation, and Darcy’s law. The heat transfer and gas flow during casting process was numerically simulated. The dangerous point of cores is firstly identified by a virtual heat transfer method based on the similarity between heat transfer and gas flow in the sand core. The gas pores in castings are predicted by the gas pressure, the viscosity and state of the melt for these dangerous points. Three distinct sand core structures were designed and used for the production of iron castings, and the simulated gas pore results were validated by the obtained castings.