. Foundry practice; a treatise on molding and casting in their various details. attached which are put on by experienced cause of difficulty in gating a casting or running in-tricate forms, as in gray iron, is the hardness of the iron,causing it to shrink more and set more quickly. The MALLEABLE CASTINGS 179 branch gate should not extend from the bottom of thefeeder, as it will chill from the sand, thus solidifyingsocner than the metal in the mold. The feeder shouldextend about one-third its length below the branch gateand should be as close as possible to the casting. Forlight pattern
. Foundry practice; a treatise on molding and casting in their various details. attached which are put on by experienced cause of difficulty in gating a casting or running in-tricate forms, as in gray iron, is the hardness of the iron,causing it to shrink more and set more quickly. The MALLEABLE CASTINGS 179 branch gate should not extend from the bottom of thefeeder, as it will chill from the sand, thus solidifyingsocner than the metal in the mold. The feeder shouldextend about one-third its length below the branch gateand should be as close as possible to the casting. Forlight patterns the branch gate should not exceed halfan inch in length, and it is preferably of circular it is difficult to feed a portion of a mold properly,a chill may be placed at that point to solidify it morequickly than the other parts, thus preventing fracture orshrink-holes. CHAPTER VIII CLEANING CASTINGS When the casting comes from the mold it has more orless sand adhering to its surface, or the cores are still inthe casting. It must be cleaned and all sand removed. Fig. 88. before it is ready for the machine shop. The gates andrisers, as well as all fins, should be chipped off. This isa portion of the cleaning and of the preparation for leav-ing the foundry. The methods of cleaning the sand from 180 CLEANING CASTINGS 181 castings may be classed under three main heads: First,the use of tumbling barrels; second, hand work; third,the use of pneumatic appliances. The tumbling barrel,
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