Metal parts produced through the forging process are known as forgings. During forging, a compressing force pressures the metal, causing plastic deformation and an alteration of the metal grain flow, whereby the metal assumes the shape of the forging die. Note that, in this process, while metal may be preheated, it is never melted or poured.
Forgings are made through two main forging methods: closed die forging, also known as impression die forging, and open die forging. In closed die forging, which is the most common die forging method, a hammer and anvil press or hammer preformed metal blanks, called ingots, into a die or set of dies that are shaped as three-dimensional negatives of the part-to-be. During this process, the hammer and anvil completely cover the workpiece, which forces the metal to spill into all areas of the die.
In addition to these steps, closed die forging frequently requires a workpiece travel through a series of impression cavities that will take it from a rough shape to the final product. The limits of closed die forging are nearly nonexistent; it can produce a countless number of 3D shapes and complex parts with tight tolerances.
The other main kind of forging, open die forging, hammers or presses metal workpieces into their desired shapes with the help of non-encompassing, simply shaped dies; dies may be convex, concave or flat. Because it usually takes multiple strikes or presses to get a workpiece to its intended shape, an operator must repeatedly reorient and reposition it, so that the die will fall onto its sections successively.
Open die forging produces forms and shapes that are simpler, like round, hexagonal and rectangular beams, bars and profiles. For this reason, and because open die tooling is less expensive, it fits best with lower volume production and the creation of unique, custom items. Other forging processes include: warm forging, cold forging, hot forging, hand forging, roll forging, drop forging and press forging.
The forging process is compatible with a number of metals, such as copper, titanium, aluminum, stainless steel, carbon steel, brass, nickel and various alloys. All metals have different characteristics, and thus offer different benefits to manufacturers and end-users. For example, copper forgings conduct electricity well, but without the risk of magnetic interference or sparking.
Titanium has a larger price tag than most, but it compensates with excellent corrosion resistance and a superior strength-to-weight ratio. Lightweight but strong and easy to forge, aluminum is another popular one. Stainless steel offers all the positive qualities of regular steel, like durability, ductility and strength, along with the property of corrosion resistance.
Similarly, carbon steel responds well to heat treatment and provides good mechanical properties at an economical price. Nickel alloy boasts oxidation resistance and exceptional stability, even when exposed to high temperatures.
Industries that utilize forgings include aerospace, agriculture, automotive, construction, defense, industrial manufacturing and mining. Forgings are particularly important to these industries because many of their applications require reliable support of human wellbeing and safety, and forgings are the strongest and most durable metal products around.
Forgings serve as components of ships, tractors, engines, tools, airplanes, automobiles, missiles, material handling equipment and more. In addition, the forging process presents design flexibility, requires minimal secondary operations and consistently produces extra strong metal parts and products with very few defects.