The linear shrinkage and shrinkage cavity rate of aluminum-richening zinc alloy is tested

and the stress is placed on the study of the underside shrinkage phenomenon of the alloy. The experimental results show that

under the condition of sand-cast

the critical mondule for occuring underside shrinkage is 1. 25 cm. The best method to eliminate underside shrinkage is to quicken the cooling rate of castings

and the underside shrinkage also can be eliminated with trace elements put into the alloys.