extrusions

Extrusion is a manufacturing process in which a material is forced through a die of a desired cross-section to create objects with a specific profile. The process is used for metals, polymers, ceramics, and foods, and is valued for producing long parts with uniform cross sections and efficient material use.

In direct extrusion, a ram pushes the billet through a fixed die; in indirect extrusion, the die is attached to the container and moves toward the stationary billet, reducing friction at the billet–die interface. Hot extrusion heats the material to improve ductility, while cold extrusion forms parts at or near room temperature for tighter tolerances. The basic steps are billet heating, lubrication, forcing the material through the die, and cooling or aging to achieve final properties. The process can produce hollow sections, solid profiles, or complex cross-sections.

Materials and products include metals such as aluminum for architectural profiles and automotive components; copper tubes; magnesium parts; polymers for tubes and profiles; ceramics in certain shapes; and in foods for shapes like pasta and snack items. Extrusion allows long, continuous pieces and sharp corners that would be difficult with other techniques.

Advantages include the ability to create complex cross sections, long continuous lengths, good surface finish, and favorable grain structure aligned with the extrusion direction. Limitations involve tooling cost and wear, energy intensity, and the requirement for sufficiently ductile materials. Post-processing may include heat treatment, sizing, and finishing.

Applications span construction, transportation, electronics enclosures, piping, and consumer goods. Variants include indirect extrusion, hollow extrusion, and hydrostatic extrusion, each offering specific benefits for particular materials and geometries.