MODELING THE INVESTMENT-CASTING PROCESS - A NOVEL-APPROACH FOR VIEW FACTOR CALCULATIONS AND DEFECT PREDICTION

A rigorous simulation of the investment casting process (including vie w factor calculations) is tedious and time consuming. During the initi al simulation stage, one needs to analyze quickly a large number of pr ocess designs to select the most promising ones for more rigorous anal ysis. Toward this end, a new model was developed for the solidificatio n heat transfer analysis of investment castings. The model is based on an approach that considers the geometric as well as the solidificatio n parameters that dominate the heat transfer and the sequence of solid ification and takes into account the radiation heat losses from the mo ld surface. A new and efficient scheme is developed for the calculatio n of view factor distribution on the mold surface, which governs the r adiation loss. This scheme is generally applicable for models with fin ite difference representation The model is capable of predicting the s olidification time profile in the casting and can be used for quick es timation of defects like hot spots which lead to macroporosities. Alth ough the proposed model is approximate, it makes only a modest sacrifi ce in accuracy while making tremendous savings in computation time. Th e model has been validated by comparison with experimental results as well as analytical solutions obtained from the literature.