球墨铸铁凝固时收缩相当大,根据我厂实际测定,大约为3.5～4.5％,有时还要大些。因此,给铸造工艺带来了很大的困难。假使铸件浇冒口系统设置得不合适,在断面厚的地方极容易产生缩孔、缩松等疵病、重者报废,轻者降低铸件质量。过去我们遇到断面 Nodular cast iron solidification shrinkage is quite large, according to my factory actually measured, about 3.5 ~ 4.5%, and sometimes larger. Therefore, the casting process has brought great difficulties. If the castings pouring riser system is set inappropriate, thick sections in the extremely prone to shrinkage, shrinkage and other flaws, heavy scrapped, the lighter to reduce the quality of castings. In the past we encountered cross-section