Gating system for introducing additives to molten metal

Claim 1

A gating system for a mold to provide for alloy additions to molten cast iron which is poured into the mold including in combination a mold cavity, a downsprue for introducing molten cast iron into the mold, a basin interposed between said mold cavity and said downsprue and being fluidly connected to said downsprue, said basin adapted to receive alloy which is to be added to molten cast iron, a consumable plastic member located in said basin and closing the exit end thereof until consumed by the action of the molten cast iron thereon, a skimmer located in said basin, passageway means fluidly connecting said basin to said mold cavity, a restriction in said passageway means comprising the smallest cross sectional flow area in the gating system and determining the dwell time of molten cast iron in said basin during a pouring cycle, the cross sectional area of said restriction being related to the casting weight as set forth as follows: CASTING WEIGHT DAM GATE EXIT AREA 10 0.17 sq. in. 20 0.28 sq. in. 30 0.32 sq. in. 40 0.46 sq. In. 50 0.55 sq. in. 75 0.65 sq. in. 100 0.72 sq. in. 125 0.81 sq. in. 150 0.90 sq. in. 175 0.98 sq. in. 200 1.06 sq. in. 250 1.15 sq. in. 300 1.24 sq. in. 350 1.32 sq. in. 400 1.40 sq. in. 500 1.48 sq. in. 600 1.56 sq. in. 700 1.72 sq in. 800 1.87 sq. in. 900 2.03 sq. in. 1000 2.18 sq. in. 1250 2.41 sq. in. 1500 2.64 sq. in. 1750 2.85 sq. in. 2000 3.06 sq. in. 2500 3.35 sq. in. 3000 3.70 sq. in. 4000 4.20 sq. in. 5000 4.60 sq. in. and being of such a size that the dwell time of the molten cast iron in said basin is between about 1 and 2 seconds, the volume of said basin being determined by the following formula: V (in.3) (Wgt. (lbs.) X D.T. (Dwell Time in seconds) X 4)/(1.25 square root weight (lbs.))