表7-3铸造用硅砂按粒度分粗/ 分组代号 主要粒度组成部分贷孔尺十 1.700,0.850,0.600 0.850,0.600,0.425 0.60,0.425,0.3 0.425,0.300,0.212 0.300,0.212,0.150 0.150,0.105,0.0075 0.105,0.0075,0.053 0.0050.053,底盘