Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed through a die of the desired cross-section.
There are two main advantages of this process over other manufacturing processes.
The first is to create very complex cross-sections. The second is to work materials that are brittle, because the material only encounters compressive and shear stresses. As an additional benefit, it also forms parts with an excellent surface finish.
Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). The extrusion process can be conducted with hot or cold material.
Commonly extruded materials include metals, polymers, ceramics, concrete, modelling clay and foodstuffs. The products of extrusion are generally called “extrudates”.
Hollow cavities within extruded material cannot be produced using a simple flat extrusion die, because there would be no way to support the centre barrier of the die.
Instead, the die assumes the shape of a block with depth, beginning first with a shape profile that supports the centre section. The die shape then internally changes along its length into the final shape, with the suspended centre pieces supported from the back of the die. The material flows around the supports and fuses together to create the desired closed shape.
The extrusion process in metals may also increase the strength of the material.
Aluminium extrusion is a technique used to transform aluminium alloy into objects with a definitive cross-sectional profile for a wide range of uses.
The extrusion process makes the most of aluminium’s unique combination of physical characteristics.
Aluminium is the most commonly extruded material and it can be hot or cold extruded. If it is hot extruded it is heated to 575 to 1100 °F (300 to 600 °C).
Examples of products include profiles for tracks, frames, rails and heat sinks.
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