Closed Die Forging

A metal billet of controlled size and weight is selected. Common materials include carbon steel, alloy steel, aluminum alloys, magnesium alloys, and titanium. The billet is heated in a furnace to the required forging temperature, which depends on the material.

The closed die set consists of an upper and lower die mounted on a forging hammer or press. The die cavities are carefully designed to match the final component shape, including allowances for shrinkage, machining, and flash formation.

The heated billet is placed into the lower die cavity. The upper die then moves downward under high force, compressing the metal. As pressure is applied, the metal flows plastically and fills the die cavity. Excess material flows out through a narrow gap between the dies, forming flash, which helps build pressure inside the cavity to ensure complete filling.

Forging may be done in multiple stages (preforming, blocking, and finishing) to reduce material flow resistance and improve accuracy.