Extrusion is a process of manufacturing long products of constant
cross-section (rods, sheets, pipes, films, wire insulation coating) forcing
soften polymer through a die with an opening.
Polymer material in form of pellets is fed into an extruder
through a hopper. The material is then conveyed forward by a feeding screw and
forced through a die, converting to continuous polymer product.
Heating elements, placed over the barrel, soften and melt the
polymer. The temperature of the material is controlled by thermocouples.
The product going out of the die is cooled by blown air or in
water bath.
Extrusion of
polymers (in contrast to extrusion of metals) is continuous process lasting
as long as raw pellets are supplied.
Extrusion is used mainly
for Thermoplastics, but Elastomers and Thermosets are also may be extruded. In this case cross-linking forms during heating and melting of the material in
the extruder.
The thermoplastic extruded
products may be further formed by the Thermoforming method.
