Ekstruusio

Ekstruusio, or extrusion, is a manufacturing process in which material is forced through a die to create objects with a fixed cross-sectional profile. The material is typically plasticized or sufficiently softened, then pushed or drawn by a screw or ram to acquire a continuous shape that can be cut to length or left as a continuous product. The process is used for both polymers and metals, as well as ceramics and some foods.

Common variants include direct and indirect extrusion, hot and cold extrusion, and hydrostatic extrusion. In direct extrusion, material is pushed through the die by a screw or ram located on the same side as the die. In indirect extrusion, the die moves with the material, reducing friction. Hot extrusion shapes metals at elevated temperatures to improve formability, while cold extrusion operates at or near room temperature for dimensional accuracy and surface finish. Hydrostatic extrusion uses a fluid medium to transmit pressure.

Equipment and setup typically involve an extruder or press, a feed hopper, a heated or cooled barrel, a die with the desired cross-section, and a cutting or winding system. Quality control focuses on dimensional tolerances, surface finish, porosity, and residual stresses, with material-specific tests for polymers, metals, ceramics, or food products.

Materials and products vary widely. Plastics are extruded into pipes, sheets, films, profiles, and coatings. Metals (notably aluminum, copper, and steel alloys) are extruded for tubes, rods, and complex cross-sections. Ceramics and food products (such as breakfast cereals and snacks) also use extrusion. The method offers net-shape production, high throughput, and design flexibility, but can entail significant equipment cost and energy use and may require secondary processing.