Why does friction impact the ram force in direct extrusion?

In the process of direct extrusion, friction plays a significant role in determining the ram force required to push the billet through the die. When the billet is extruded, it is subjected to compressive forces as it is pressed through a die. The friction between the billet and the walls of the container contributes to the resistance encountered during this process.

As the billet compresses against the walls, the frictional force acts in opposition to the movement of the material. This friction not only affects the overall efficiency of the extrusion but also increases the amount of ram force needed to overcome that resistance. The greater the contact surface between the billet and the container walls, the higher the frictional force, and therefore, the greater the ram force required.

Understanding this relationship is crucial for optimizing the extrusion process, as it directly impacts the energy efficiency and the quality of the extruded product. The other options incorrectly imply that friction is minimal or insignificant, when in fact it is a vital factor in determining the ram force during extrusion.