Discover what is the manufacturing forming process Extrusion and its usage in the industry.
The extrusion process can create objects with fixed cross-sectional profiles by pushing a material, most commonly metals, polymers, ceramics, concrete, modeling clay, and foodstuffs, through a die of the desired cross-section. This is beneficial for creating very complex cross-sections and with fragile materials because the material is only exposed to compressive and shear stresses. One key advantage is the excellent surface finish. Another is the increased strength of metal objects produced with extrusion.
Two types of extrusion exist: continuous or semi-continuous. Continuous extrusion involves the production of an indefinitely long material; semi-continuous involves the production of many pieces. The material can be either hot or cold. Extrudates is the term for objects produced with extrusion.
In 1797, the English inventor Joseph Bramah patented the first extrusion process for making pipe out of soft metals. The metal was preheated and forced through a die via a hand-driven plunger. Later, in 1820, Thomas Burr implemented this process with a lead pipe and a hydraulic press called “squirting.” Alexander Dick went on to expand the extrusion process to copper and brass alloys in 1894.
The extrusion process also has some drawbacks. They include surface and internal cracking, surface lines, and a “pipe,” which is a flow pattern that draws surface oxides and impurities to the center of a product.
The five different extrusion processes are:
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