Forge
the apparatus or works for heating bars of iron and steel and working them under the hammer. Works in which cast iron from the blast furnaces is converted into malleable iron by puddling and subsequent hammering, and also where the native ores of iron are reduced without fusion to the metallic state, are also called forges. Forges are required of various dimensions, and are often adapted to special uses. Portable forges are used in many workshops. For forging heavy articles, as anchors, wrought-iron shafts for ocean steamers, etc., powerful machinery is required, adapted to the nature of the work to be done. Morrison's steam hammer, with which a bar of iron can be forged of any size or thickness, is one solid wroughtiron hammer bar, piston head and head for hammer face forged solid, with the bar passing through both ends of the cylinder, prevented from turning by the upper cylinder head. No guides below the cylinder. Slide-valve balanced.
Double-acting hammers of all sizes, taking steam above and below the piston, with self-acting valve gear and hand movement, can be changed at will while in operation, thus affording complete control over its movements. Hammers of 2,000 pounds and under have one upright only; those over this size, two. In puddling iron, when the mass of castiron has been sufficiently purified in the furnace by burning out its carbon and other impurities, it is placed under the heavy forge hammer, which squeezes out the liquid slag and forces the softened particles of iron to cohere into a continuous oblong mass or bloom. When iron is extracted from rich ores without first being converted into cast-iron, the forge hammer is used to force the spongy mass of reduced ore into a compact bar of malleable iron.