A MODEL FOR BINDER GAS GENERATION AND TRANSPORT IN SAND CORES AND MOLDS

Gas defects are often found in sand-cast parts that arise from gas generated by thermal decomposition of the sand binder. Typically, these defects occur with sand cores that have not been adequately vented. A new computational model has been developed that predicts the generation of decomposed binder gas and its transport within cores. The binder gas is treated as compressible to account for poor venting scenarios and for transport across core regions of steep temperature gradients. The model considers true molding geometry and actual core venting locations and can be used to predict the amount of gas that would enter liquid metal from any location on the surface of the core.