What is a key difference between direct and indirect extrusion?

In the context of extrusion processes, the key difference between direct and indirect extrusion lies in how the die interacts with the ram and the material being extruded.

In direct extrusion, the material, or billet, is forced through the die by a ram, and the die is positioned at the end of the extrusion chamber. This results in the material moving directly towards the die, allowing it to take the shape of the die opening as it exits.

In contrast, indirect extrusion involves a different setup where the die is mounted on the ram itself. Here, the ram moves toward the stationary billet, and as it pushes, the material is extruded through the die that is positioned at the end of the ram. This process means that during the extrusion, the die is involved in the movement of the ram, which is a fundamental distinction from direct extrusion. This configuration can lead to different mechanical properties and strength characteristics in the extruded material.

Thus, the statement regarding indirect extrusion involving the die in the ram accurately highlights this critical difference in operational mechanics between direct and indirect extrusion methods.