In direct extrusion, also known as forward extrusion, metal extrusion units load a metal billet into a container, while a ram compresses the material, forcing it to flow through a die opening at the opposite end of the container.
Also known as forward extrusion, in direct extrusion, the billet moves in the same direction as the punch and ram. The billet slides against the stationary wall of the container, creating high friction between the two, which results in the requirement of greater forces. Oxidation of the billet in hot extrusion is prevented by the use of a dummy block which has a slightly lower diameter than the billet. By using a hollow billet and a mandrel that can be attached to the dummy block, hollow sections like pipes and tubes can be extruded by this direct method.
In one single process step, semi-finished products like profiles, tubes, plates, or films can be produced by direct extrusion or in-line compounding. Intermediate pelletizing that is typical for products like plastics is generally omitted in inline compounding, because of which the operating costs, investment and energy requirements at metal extrusion units in India can be dropped drastically.