When liquid metal is poured into the mold, it will produce volume shrinkage during cooling and solidification. This shrinkage may lead to defects in the last solidified part of the axle housing – shrinkage cavity or porosity. Common casting alloys with large volume shrinkage, such as cast steel, malleable cast iron and some non-ferrous metal alloys, have such defects, so it is necessary to design feeding system to solve them.
Shrinkage cavity and porosity defects in sand casting have a significant impact on the compactness of the axle housing, which will greatly reduce the effective bearing area of the axle housing, lead to failure to meet the mechanical property requirements, and even directly scrap the products in serious cases. In engineering practice, the defect is usually compensated by setting risers. The riser is mainly used to compensate the defects of the axle housing by storing liquid metal, and can vent gas and collect slag at the same time.
Due to the chilling effect of chilled iron, the solidification rate of the part pasted with chilled iron on the surface of sand casting axle housing is faster than that of the adjacent section. Generally, in order to obtain a dense axle housing, cold iron can be used as the end area to reduce the number of risers and improve the process yield of the axle housing.
According to the results of computer simulation of sand casting axle housing, risers and chill are added, and then computer sand casting axle housing simulation is carried out to observe the quality of axle housing and study the influence of risers and chill on solidification process.