ZA－27合金砂型铸造产生的底缩是凝固期中Zn的宏观偏析引起的。富锌合金液最后凝固,铸件先凝固部分的收缩处从底部供应补缩金属。用录像法观察了底缩现象后指出:缩孔产生于合金已凝固79~90%时。可以通过使用冷铁和冒口、控制铸件成分的宏观偏析,来解决底缩问题,同时,提出在设计铸件时,使用晶间液体流动的模似分析避免底缩。 ZA-27 alloy sand casting bottoming is caused by the macro-segregation of Zn in the solidification period. The zinc-rich alloy fluid is finally solidified, and the constriction of the solidified portion of the casting is supplied with the metal filler from the bottom. After observing the phenomenon of end-shrinkage by video, it was pointed out that the shrinkage cavity was produced when the alloy had been solidified at 79 to 90%. The problem of underfilling can be solved by controlling the macrosegregation of the cast components by using chilled iron and riser. Simultaneously, it is proposed to simulate the flow of intercrystalline liquid to avoid undercutting during the design of castings.