Drop ForgingDrop forging is a metal shaping process where a heated workpiece is formed by rapid closing and opening of a die, which gradually forces the workpiece to conform to the die cavity’s shape. This is a modern form of smith forging—the manual force of the blacksmith has been replaced by a hardened alloy steel mechanical or steam hammer. This forging process produces many parts for the automotive industry, including crank shafts, stub-axles and gears. Chains, hooks, shackles, bolts rods, medical implants, parts in transmissions, suspensions, industrial equipment and all sorts of tools are also produced by drop forging. These parts are used by the aerospace, agriculture, railroad and military industries, and they are also referred to as impression die forging, closed die forging or rot forging. The drop forging process uses heated pre-formed shapes made of aluminum, copper, nickel, steel, stainless steel and magnesium. The metal must be able to harden, have a high temperature resistance, and resistance to cracking when heated. Mild steel is the best metal for this process, while magnesium performs poorly. The hammer gradually forms the heated metal by singular or repeated blows in a sequence of individual or multi-staged die cavities. It is powered by air, hydraulics or mechanics, and the striking force is between 11 thousand to 425 thousand pounds. The parts are made with parting lines and flash, which is always removed. The forging dies are solid blocks of hardened alloy steel that are made in halves—one is attached to the rising and falling block, while the other is attached to the stationary anvil on the bottom. Drop forging is considered the most widely used form of forging, and produces parts that exhibit superior load bearing strength.
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