Drop forging is a kind of forging process different from press forging, upset forging or other forging processes. In drop forging, the billet is deformed into desired shapes with the help of forging dies. Types of drop forging are open-die drop forging and closed-die drop forging. The shape of the die is the main differences between open die drop forging and closed die drop forging like the names. Closed die drop forging does fully encloses the workpiece, while open die forging does not.
Closed Die Drop Forging
Closed die drop forging, or closed die forging, is a forging way that presses heated round metal bar into the shape we need under the pressure of the dies. It will ensure the accuracy of dimensions and little machining allowance, no structure limit, high production efficiency. General steps of closed die drop forging are: mould developing-raw material cutting-heating material-forging-trimming cutting-heat treatment-shot blasting-machining-surface treatment-package. Materials that applied in drop forging process can be stainless steel, alloy steel, carbon steel, copper and other forged materials.
Open Die Drop Forging
Open-die drop forging is also known as smith forging. In open-die forging, a hammer strikes and deforms the billet, which is placed on a stationary anvil. Open-die forging gets its name from the fact that the dies do not enclose the workpiece, allowing it to flow except where contacted by the dies. The operator therefore needs to orient and position the workpiece to get the final shape. The dies are usually flat in shape, but some have a specially shaped surface for specialized operations. For example, a die may have a round, concave, or convex surface or be a tool to form holes or be a cut-off tool. Open-die forgings can be worked into shapes which include discs, hubs, blocks, shafts (including step shafts or with flanges), sleeves, cylinders, flats, hexes, rounds, plate, and some custom shapes. Open-die forging lends itself to short runs and is appropriate for art smithing and custom work. In some cases, open-die forging may be employed to rough-shape ingots to prepare them for subsequent operations. Open-die forging may also orient the grain to increase strength in the required direction.
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