1) One slow, two fast and three steady. In the early stages of pouring, especially the moment when the molten metal first contacts the foam plastic, due to the large amount of gas produced by the vaporization of the pattern material, the static pressure head of the molten metal is smaller than that of the decomposition products of polystyrene when the sprue is not full or when pouring has just begun.
When the gas pressure is high, pouring too quickly can easily cause choking and cause the molten metal to splash. In order to avoid this phenomenon, at the beginning of pouring, a trickle and slow pouring method can be adopted.
After the pouring system is filled with molten metal, the pouring speed can be increased. The faster the better, but the pouring cup should be filled with metal. No spillage is the rule. In the later stage of pouring, when the molten metal reaches the top of the mold or the root of the riser, the package should be slightly closed to keep the metal rising steadily and prevent the molten metal from rushing out of the riser. 2) The pouring process cannot be interrupted. When pouring lost foam castings, molten metal must be continuously injected until the mold is completely filled.
Otherwise, it is easy to cause cold insulation defects on the entire plane of the casting at the stop. 3) Use ante packages whenever possible. The heat loss of the molten metal in the bottom injection package is small, the pressure head is large, the pouring speed is fast, the slag floats on the upper surface of the molten metal, and the molten steel is relatively clean. Subject to equipment conditions, subcontracting can also be used for some low-demand or general small and medium-sized iron castings.
Link to this article：Three principles should be followed when pouring lost foam castings
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