LEADED YELLOW BRASSES

Melting practice for leaded yellow brasses is generally similar to that for tin bronzes and tin-lead bronzes.
Although there is usually little difficulty from gas absorption, the combustion atmosphere should be slightly oxidizing. The metal should be super­ heated only enough to permit handling and pouring at the required temperature. After removal from the furnace, the alloy should be skimmed carefully and permitted to stand in the open air until it reaches the proper casting temperature.
Hydrogen absorption is usually at a minimum because the large quantity of zinc vapor con­tinually sweeps it away from the melt.
Yellow brasses show fairly high shrinkage during solidification and freezing. Gates and runners must be somewhat larger than for tin bronzes. Risers also must be large to provide for ample feeding of the sec6ons. To avoid drossy or dirty castings, gating must be arranged so that the metal enters the mold without agitation. Strainer cores and choke gates should be used when possible.
Pouring should be done carefully. Sprues should be choked and kept full. Sprue diameter should be as small as possible.