Metallurgy Of Cast Iron

ORIGIN AND UTILITY OF STANDARDIZED DRILLINGS. 185
tion after the mould has been filled, which in turn is most beneficial in causing the metal in the mould to mix well, and counteract variations in structure that might otherwise take place. The metal dropping
FIG. 46.
from the top gates B causes a disintegrating action, cutting into fine particles any dirt that might acctimu-late upon the surface of the rising metal, and which, were it not thus chopped up, as it were, into fine particles, would gather in large lumps and be caught and held fast in the mold walls, with the result that dirt spots,pouring it. At A is a gate leading down to the bottom of the mold at an inlet at D. The round gates B, seen at the top of the mold, are placed about four inches apart and are one-half inch in diameter. A riser is seen at E. In starting to pour the mould, the molten metal is directed to drop from the ladle into the basin at the point marked W, in a way that will allow it to flow gently down the gate A and enter the mould at D to prevent the bottom being cut by the top gates. When from thirty to fifty pounds of metal has entered the mould, a quick turn of the ladle empties a large body of the metal into the pouring basin, quickly filling all the gates at B; this then drops the metal down upon that which is rising from the stream flowing in at D. This action is kept up until the mould is filled and the metal runs out at the riser E. After this point is attained, the pouring is slackened and a steady stream maintained until from three hundred to five hundred pounds of metal has flown through the riser E to run down the incline seen at S into the scrap hole X. The effect of allowing such a large body of metal to flow through the mould by making it enter the gate at A is to keep up an agita-ing only open or close grained iron in connection with exacting any certain specified analyses from blast furnaces, as the slight difference possible in the most radical cases of open and close grained iron can be regulated by a slight variation in silicon when making a mixture, and which anyone can easily do, if they so desire, "