抄録
Through the detailed investigation made on the fluidity of molten metal in casting to which the step gates are attached, the author has obtained the following conclusions.
1) The condition of fluidity of molten metal in the step gates is affected by the sizes of sprue, ingate and the casting, besides the pouring rate of metal. In case of the pouring rate is fast, the molten metal flows back from casting to sprue through the upper ingate if the diameter of the ingate is smaller than that of sprue. To protect this flow back, the diameter of sprue should be chosen as about 80 percent of the diameter of ingate. In case of the pouring rate is slow, the flow back is hardly to occur if the diameters of sprue and in gate are same.
2) When the level of the molten metal in sprue exceeds the level of the upper ingate, the metal flows into the casting from both upper and lower ingates, however, the amount of inflow from the lower ingate is greater than that of from the upper ingate if the pouring rate is fast, and the opposite can be said when the pouring rate is slow.
