Extrusio

Extrusio is a manufacturing process in which a material is forced through a shaped opening, or die, to produce objects with a continuous cross-section. The name derives from Latin extrudere, to thrust out, and is used in metalworking, plastics processing, and to a lesser extent ceramics and composites to form long parts with uniform profiles.

In metal extrusion, a billet is heated and loaded into a chamber; a ram or screw applies force, pushing the material through a die. In polymer extrusion, solid or pelletized resin is melted and pumped through a rigid die, with the output typically drawn or cut to length. The die geometry determines the final cross-section; multiple dies or coextrusion can produce complex shapes and multi-layer products.

Common forms include hot extrusion, cold extrusion, direct and indirect extrusion, and, in plastics, extrusion and blown film processes. Hot extrusion lowers flow stress and enables larger cross-sections; cold extrusion yields high-strength parts with good surface finish but requires more force.

Applications include structural profiles (rails, channels, fins), pipes and tubes, electrical conduits, automotive and aerospace components, and consumer packaging. Extrusio can also refer to filament deposition in additive manufacturing contexts where materials are extruded from a nozzle.

Advantages include high production rates, efficient material use, and the ability to produce long parts with accurate cross-sections. Limitations include significant equipment cost, die wear, frictional heating, residual stresses, and limitations with certain materials or very small or complex cross-sections. Post-processing such as heat treatment, annealing, or sizing is common.