一般普通砂型铸造的铸件表面比较粗糙,所以,设计人员往往只是在图纸上标注不加工符号,或注明“铸件表面必须光洁”的说明。铸件表面粗糙度,不仅会影响铸件与整台机器的外观质量,而且影响使用性能。例如,我厂生产的空气锤,由于缸体铸件气道部位的表面粗糙度较高,空气锤的打击能量就显著增加。据有关资料介绍,当水泵叶轮流道的粗糙度由R_α12.5_(μm)降低到R_α6.3_(μm)时,水泵的效率可以提高3～5％左右;而汽轮机叶片的铸 Ordinary sand casting castings rough surface, so designers often just drawing not marked on the drawings, or indicate “casting surface must be smooth,” the instructions. Casting surface roughness, not only will affect the appearance of castings and the quality of the entire machine, but also affect the performance. For example, the air hammer produced by our factory, due to the high surface roughness of the airway part of the cylinder casting, significantly increases the striking energy of the air hammer. According to relevant information, when the roughness of the flow path of the pump impeller is reduced from R_α12.5_ (μm) to R_α6.3_ (μm), the efficiency of the pump can be increased by about 3~5%; while the casting of the turbine blade