Closed die forging

Die forging is a process in which material is placed in a mold-like die attached to an anvil. The die is then dropped onto the workpiece, causing the material to flow and fill the die. Depending on the size and complexity of the part, the tool may drop many times (many times in milliseconds) in a series of rapid movements. The excess material that is squeezed out of the die cavities is referred to as efflux. The efflux cools faster than the rest of the material and typically has higher properties than the material in the die, which helps prevent more efflux from forming. The efflux also forces the material to completely fill the die cavity, and is removed after forging.