Thermal modeling of molten metal front in lost foam iron casting

During mold filling in lost foam casting, the molten metal front interacts directly with the polystyrene foam pattern, producing a temperature distribution that fundamentally differs from that in conventional empty-mold casting. Accurate prediction of the temperature distribution at the molten metal front is critical for process optimization and defect control. In this work, a novel physical model was established to characterize the front temperature distribution and interface evolution. Three coupled heat transfer mechanisms are identified as the primary drivers of front temperature variation: (i) heat exchange between the molten metal and the foam pattern, (ii) convective heat transfer within the molten metal, and (iii) heat exchange between the molten metal and the sand mold wall. Based on a radial advancement hypothesis, an interface evolution algorithm was proposed. The heat exchange between the molten metal and the foam pattern is quantified using the latent heat associated with foam gasification. The convective heat transfer within the molten metal is determined by solving the momentum and energy equations, with a specially devised velocity boundary constraint imposed at the filling front, where the normal velocity is specified by a previously established empirical formula. An effective heat transfer coefficient is adopted to simplify the metal-mold heat exchange calculations. The reliability of the developed model was verified through dedicated casting experiments and validated in industrial production. The proposed method provides a reliable and practical tool for predicting filling-related defects and optimizing the process design of lost foam iron castings.