What is forging?

Forging is manufacturing process where metal is pressed, pounded or squeezed under great pressure into high strength parts known as forgings. The process is normally (but not always) performed hot by preheating the metal to the desired temperature before it is worked. It is important to note that the forging process is entirely different from the casting (or foundry) process, as the metal used to make forged parts is never melted and poured (as in the casting process).

Why use forgings and where are they used?
The forging process can create parts that are stronger than those manufactured by any other metalworking process. This is why forgings are almost always used where reliability and human safety are critical. But you'll rarely see forgings as they are normally component parts contained inside assembled items such an airplanes, automobiles, tractors, ships, oil drilling equipment, engines, missiles and all kinds of capital equipment - to name a few.

What is drop forging?


Drop forging is a metal shaping process, the metal to be formed is first heated then shaped by forcing it into the contours of a die, this force can be in excess of 2000 tons. The drop forging process can be performed with the material at various temperatures;

Hot Forging

During hot forging, the metals are heated to above their recrystallization temperature. The main benefit of this hot forging is that work hardening is prevented due to the recrystallization of the metal as it begins to cool.

Cold Forging
Cold Forging is generally performed with metal at room temperature below the recrystallization temperature. Cold forging typically work hardens the metal.

There are two types of drop forging, open die and closed die.

Open die drop forging requires the operator to position the workpiece while it is impacted by the ram. The die attached to the ram is usually flat or of a simple contour, most of the shaping is achieved by the operator physically positioning the workpiece before each stroke of the ram. There are also special dies which can be used to cut the metal, form holes or notches. see more

Closed die drop forging comprises of a die on the anvil which resembles a mould, the ram which falls and strikes the top of the metal billet can also be equipped with a die. The heated metal billet is placed on the lower die while the ram drives down forcing the metal to fill the contours of the die blocks.

Materials and applications
Forging of steel
Depending on the forming temperature steel forging can be divided into:

Hot forging of steel

Forging temperatures above the recrystallization temperature between 950 - 1250 °C
Good formability
Low forming forces
Constant tensile strength of the workpieces
Warm forging of steel
Forging temperatures between 750 – 950 °C
Less or no scaling at the workpiece surface
Narrower tolerances achievable than in hot forging
Limited formability and higher forming forces than for hot forging
Lower forming forces than in cold forming

Cold forging of steel

Forging temperatures at room conditions, self-heating up to 150 °C due to the forming energy
Narrowest tolerances achievable
No scaling at workpiece surface
Increase of strength and decrease of ductility due to strain hardening
Low formability and high forming forces are necessary
For industrial processes, steel alloys are primarily forged in hot condition. Brass, bronze, copper, precious metals and their alloys are manufactured by cold forging processes while each metal requires a different forging temperature.