过去,我厂采用树脂自硬砂制芯所生产的铸件,普遍存在着气孔、针孔等缺陷,每年因这些缺陷而报废的铸件就有20余t。其主要原因是配制树脂砂芯的原砂质量太差,原砂粒形不好,粒度过于分散,含粉量、含泥量和杂质较多,因此,配制时树脂的加入量必须高达2.8%。这就使得树脂砂成本增加,透气性下降,发气量大,从而导致大量的气孔、针孔缺陷产生,铸件报废。现在,我们采用含泥量、含粉量和杂质少而SiO_2含量多的福建晋江西脚砂场产的天然水洗硅砂(简称晋江砂),使树脂的加入量降低到1.8%,铸件 In the past, I plant the use of resin from the hard-core production of castings, the prevalence of pores, pinholes and other defects each year due to these defects and castings have more than 20 t. The main reason is that the resin sand core is poorly prepared, the original sand shape is not good, the particle size is too scattered, the content of dust, mud content and impurities are more. Therefore, the amount of resin added must be as high as 2.8%. This makes the resin sand costs increase, decreased permeability, gas evolution, resulting in a large number of pores, pinhole defects, casting scrapped. Now, we use natural washed silica sand (Jinjiang sand) produced in Fujian Jinjiang West Foot Sandyards with less mud content, less dust content and less SiO_2 content, reducing the amount of resin added to 1.8%