Closed Die Forging
Closed die forging, also known as impression die forging, involves the movement of metal blanks through a set of dies shaped in the required part design. Closed die forging is the most common method of forging utilized in the industry and is done by two dies coming completely together. Offering grain-flow optimization and increased fatigue resistance, close die forging is used to produce intricate and difficult geometries. In addition, closed die forging is the most cost-effective tooling solution for high volume production. Capable of producing symmetrical and non-symmetrical parts, materials that typical undergo closed die forging processes include high alloy steel, naval brass, carbon steel, aluminum alloy, stainless steel, copper nickel, tool steel and titanium. Closed die forgings are particularly beneficial for industries such as electronics, aerospace, automotive, commercial, industrial, semiconductor, construction, hardware and food processing.
Closed die forging machines consist of two tooling dies, a stationary die and a moving die, and a flash gutter. Both dies contain impressions of the desired part shape. The moving die presses down onto the stationary die and the metal, or workpiece is plasticized while being completely inside the walls of the two dies in an area called the flash gutter, which is a recess that is formed at the interface of the two dies. This recess is a 3-D impression of the desired shape. Since the workpiece is contained, the flow is restricted by the contours of the flash gutter and formed into the shape. Excess metal is usually formed on the closed die forging and will be later machined off. The closed die forging process can be done in with cold forging, hot forging or warm forging. In cold forging the metal is not directly heated, but formed using high pressure. In hot forging the metal is heated to high temperatures then formed. In warm forging the metal is heated to a range that is typically above room temperature, but below the recrystallization temperature.