Burrless Die Forging

the hot deformation of metal blanks in closed dies without the loss of metal in the form of burrs. It is used to obtain accurate forge work having the shape of solids of revolution and blanks used in forging parts having a complex shape (such as four-way unions and fittings). Burrless die forging is carried out with hammers, presses, and horizontal forging machines. When forging with hammers, the projecting portion of the die impression is placed in the lower die, and the deep cavity is placed in the upper die, in order to facilitate extraction of the forging from the die. The lateral surface of the projecting portion of the lower die, together with the lateral surface of the recess in the upper die, serves to lock the dies on center. For burrless forging of pieces with deep inner cavities, dies with ejector pins are used. Burrless die forging creates a condition of tension approaching irregular all-sided pressure, as a result of which the metal can be deformed at relatively low tensile stress, which is important for materials of low plasticity, such as heat-resistant alloys.