forging, shaping metal by heating it and then hammering or rolling it. Forging is the method by which metal was first worked when it came into use about 4000 B.C. in Egypt and Asia. Modern forging is done with a power-driven hammer; Dies are usually used. These are steel blocks hollowed out or carved in relief in the shape of the desired part. One die is stationary, the other is attached to the underside of a hammer or press ram. A piece of metal is then hammered or squeezed until it takes on the shape of the die cavity. Sometimes there are several sets of dies that form the metal in stages into the final shape. Smaller parts may be forged cold; larger parts, hot. Maximum pressure exerted is about 100 tons per square inch. Variations of the forging process are called sizing, heading, and coining. Some industrial machines for forging are the drop hammer, steam hammer, and hydraulic press. Forging toughens iron and steel, while casting makes them brittle.

In metallurgy, the process of shaping metal and increasing its strength by hammering or pressing. In most forging an upper die is forced against a heated workpiece positioned on a stationary lower die. To increase the force of the blow, power is sometimes applied to augment gravity. The number of blows struck is carefully gauged by the operator to give maximum effect with minimum wear on the die. Forging presses employ hydraulic or mechanical pressure instead of blows; most can exert only a few hundred tons of pressure, but giant presses, used for forging parts of jet aircraft, are capable of up to 50,000 tons of pressure. Seealso drop forging.

Learn more about forging with a free trial on Britannica.com.