Experimental and CFD Modeling of Microshrinkage in A356 Silica Sand Mold Castings

A computational fluid dynamics (CFD) casting simulation-based optimization approach previously developed was applied in this study to assist in the improvement of the mold design of cast components made of A356 alloy.  By using this approach, solidification related defects (including shrinkage porosity) were significantly minimized and hence it helped in cost reduction, performance enhancement and quality assurance of complex A356 cast parts.

An experimental validation and detailed calibration and verification procedures of the model for prediction of the microshrinkage were performed using A356 plates cast in no-bake silica sand molds. Correlations between Niyama values and the pore percentage as well as between Niyama values and pore size were developed. Thus, the severity level of shrinkage porosity and pore dimensions can be estimated by using the Niyama criterion. Predictions were then compared with the porosity measurements in plates of various plate thicknesses and in other commercial A356 casting components. The predictions were in good agreement with the experimental measurements.