Forging is a manufacturing process that involved forming and shaping metals through compressive forces like hammering, pressing, or rolling. The original metal is deformed into a new shape with a higher strength and fatigue resistance. There are many different types of forging including drop forging in which a hammer hits the metal either into a die or onto a stable work surface, roll forging in which a piece of metal is pushed through two horizontal rolls, and press forging in which a continuous force is applied to shape the metal. Many different kinds of metal can be forged and forging can be done cold or hot.
Hot forging is when the piece of metal being worked on is heated anywhere between 360 °C all the way up to 1150 °C, depending on the metal. The temperature will rise above the recrystallization point of the metal to decrease the hardness so the metal is easier to manipulate. This means less energy is required to form the metal. Other advantages of hot forging include an increase in diffusion resulting in more chemical homogeneity, an increase in ductility, an increase in strength of the metal, and the possibility for acute customization. Disadvantages of hot forging include less precise tolerances, potential rapid oxidation of the piece, and time needed for cool down, which must be done carefully to avoid warping. Heating units can also be expensive.
Cold forging is similar to hot forging, but metal is not heated. Instead, the metal is formed below its recrystallization point at or near room temperature making it a better option for softer metals. Pieces formed through cold forging require little or no finishing work and there it produces little to no waste through precision shapes. Cold forging can handle high stress, has high production rates, and has improved interchangeability. Disadvantages include less ductile metal, only certain shapes can be produced, and the process requires heavier, more powerful equipment and tooling, which can be expensive.
Forging is a vital part of our economy, with parts being forged for use in fields like national defense, automotive manufacturing, mining metals and oil, even surgical and dental instruments can be made of forged metal. Forging has been used for millennia and continues to provide solutions for industries across the globe.