Editing Forge (section)

=== Drop forging ===
Drop forging is a process used to shape metal into complex shapes by dropping a heavy hammer with a die on its face onto the workpiece.<ref>Manufacturing Processes Reference Guide; Todd, Allen, Alting</ref>

==== Process ====
The workpiece is placed into the forge. Then the impact of a hammer causes the heated material, which is very malleable, to conform to the shape of the die and die cavities. Typically only one die is needed to completely form the part. Extra space between the die faces causes some of the material to be pressed out of the sides, forming [[Flash (manufacturing)|flash]]. This acts as a relief valve for the extreme pressure produced by the closing of the die halves and is later trimmed off of the finished part.

==== Equipment ====
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The equipment used in the drop forming process is commonly known as a [[Power hammer|power]] or drop hammer. These may be powered by air, hydraulics, or mechanics.  Depending on how the machine is powered, the mass of the ram, and the drop height, the striking force can be anywhere from 11,000 to 425,000 pounds.
The tools that are used, dies and punches, come in many different shapes and sizes, as well as materials. Examples of these shapes are flat and v-shaped which are used for open-die forging, and single or multiple-impression dies used for closed die forging. The designs for the dies have many aspects to them that must be considered. They all must be properly aligned, they must be designed so the metal and the flash will flow properly and fill all the grooves, and special considerations must be made for supporting webs and ribs and the parting line location. The materials must also be selected carefully. Some factors that go into the material selection are cost, their ability to harden, their ability to withstand high pressures, hot abrasion, heat cracking, and other such things. The most common materials used for the tools are carbon steel and, in some cases, nickel-based alloys.

==== Workpiece materials ====
The materials that are used most commonly in drop forging are aluminium, copper, nickel, mild steel, stainless steel, and magnesium.  Mild steel is the best choice, and magnesium generally performs poorly as a drop forging material.