【Summary】 When it comes to the characteristics of grey iron castings, its clay content is relatively high. Because, the molding sand with the high clay content will increase with the pressure. In general, in terms of effective bentonite, in fact, it should be controlled between 7% and 10%. In terms of the molding sand used in producing grey iron castings, its sediment percentage means the sum of the active clay and the dead clay.
Moreover, in terms of the sediment percentage of the grey iron castings under normal circumstances , we should pay attention to directly controlling it between 12% and 16%. If the sediment percentage is too high or too low, to a great extent, it will affect the performance indexes of molding sand directly.
Then, when it comes to grey iron castings, its moisture is relatively low. for the manufacture of EPC casting molding sand moisture is also determined plastic and adhesive force of the main factors of the clay itself. When the water is relatively high, to a large extent, it is easier to cause the deterioration of the clay adhesion. Then, in fact, we should pay attention to that the liquidity of sand will decline. So it will not get a relatively homogeneous mould density.
Furthermore, when the water of castings is low, the molding sand also won't mix well. In view of this, when the intensity of the molding sand is low, the brittleness will be relatively large, and the modularity will be very poor, so it is easier to make the casting itself directly have the defects of the burnt-on sand.
The amount of pulverized coal on the castings will be relatively low. In this case, we should pay attention to its original grit. When it is high-density modeling, the density of the molding sand will be higher. And it will expand relatively large when pouring. Because of this, we should pay attention to that the primary grit which used in producing the grey iron castings can not be too centralized.