The prediction of shrinkage casting defects is based on the simulation of temperature field, and then the shrinkage of sand castings at each time is calculated according to the different solid-liquid state of each unit at each time. The prediction of shrinkage casting defects includes the prediction of shrinkage shape, size and position.
In the solidification process of sand castings, each unit needs to experience liquid-solid coexistence zone and solid state. When the solid rate of the unit is higher than the critical solid rate, the unit will no longer have the ability to flow, so it can not be fed. Therefore, in the figure, only the units in the region have feeding capacity.
In the process of predicting shrinkage casting defects, it is necessary to effectively judge the dynamic isolated hot spot, and then calculate its shrinkage at each time step. The feeding order is from the center of the hot spot to the outside.