Extrusion Presses
During indirect extrusion, there is essentially no relative sliding between the billet and the container. This reduces the influence of container-wall friction on load and temperature variation and can support more consistent conditions along the extrusion length.
In a typical indirect extrusion process, the die is mounted on a hollow stem or corresponding actuating structure and moves toward the billet. Metal passes through the die and exits in the direction opposite to the die motion. Because the billet remains essentially stationary relative to the container, sliding friction between the billet and the container wall is significantly reduced.
The actual degree of improvement in indirect extrusion depends on material, billet surface, temperature, extrusion ratio, die, speed and equipment control, and must be evaluated against the specific product conditions.