型砂和坭心砂必须具有一定的物理机械性能,此种性能应保证能为合格铸件而制出所要求的砂型和坭心。型砂的物理机械性能,应根据铸件的重量和铸造的方法(干模或湿模)来确定。坭心砂的物理机械性能,应根据坭心的大小和形状以及坭心在砂型中的工作条件来确定。型砂和坭心砂的配制成分,则应根据砂子、粘土和粘结剂的种类和性制而定。 Sand and sand heart must have a certain physical and mechanical properties, such performance should ensure that qualified castings made the required sand and heart. Physical and mechanical properties of sand, castings should be based on the weight and method of casting (dry or wet mode) to determine.坭 Sand physical and mechanical properties, should be based on the size and shape of the heart and the heart in the sand to determine the working conditions. The preparation of sand and sand should be based on the type and nature of the sand, clay and binder.