铸造有色金属的大型和中型另件时,使金属液从底部引入到铸件的厚壁部分(图中虑线),能保证金属平稳地浇满铸型,并可获得没有气孔的铸件,但在浇口处往往容易产生缩孔⑥。一般防止缩孔的方法——增加内浇口截面积,安放冷铁,改善型砂和硬模塗料,选择适当的浇铸温度等——不能保证工艺上的稳定性,因此就常常不能消减废品。 Casting non-ferrous metal large and medium-sized pieces, the introduction of molten metal from the bottom to the thick part of the casting (in the figure), to ensure smooth metal casting mold, and can obtain non-porosity casting, but in Gate is often prone to shrinkage ⑥. The general method to prevent shrinkage - increase the cross-sectional area of ​​the gate, the installation of chilled iron, sand and hard coating to improve mold, select the appropriate casting temperature - can not guarantee the stability of the process, it often can not reduce the waste.