extrude

Extrude is a shaping process in which material is forced through a shaped opening or through a die, or a two‑dimensional profile is extended along a direction to create a three‑dimensional object. It is used across manufacturing disciplines to produce parts and lengths with a constant cross-section, such as rods, tubes, and profiles, and it also refers to a computer-aided design operation that creates a 3D form from a 2D sketch.

In metal and polymer manufacturing, extrusion typically begins with a billet or feedstock placed in a loading chamber. A ram or screw pushes the material through a die, producing a continuous or long part. Variants include direct extrusion (where the billet is pressed toward the die) and indirect extrusion (where the die moves toward the billet, reducing friction). Hot extrusion, performed above the material’s recrystallization temperature, lowers forming forces and enables complex shapes; cold extrusion, done at or near room temperature, yields better surface finish and tighter tolerances but requires higher forces. The process can produce long sections such as rails, bars, pipes, and flexible profiles, with material choices including metals, plastics, and ceramics.

In plastics, extrusion often uses a screw extruder to melt polymer resin, which is then forced through a die to form pipes, tubing, films, sheets, or profiles. In food processing, extrusion produces snack foods, breakfast cereals, and pasta by forcing ingredients through dies under heat and shear.

In CAD and 3D modeling, extrusion refers to converting a 2D shape into a 3D solid by extending it along a specified direction, with parameters that control depth, draft, and finishes.

Factors influencing extrusion quality include die design, material properties, temperature, friction, and cooling.