The most important element: extruders
Any extruder machine has the responsibility to process thermoplastics dosed in pellets to generate an unlimited cross section in fluid plastic that will take its geometry according to our die and calibrators adapted to the output of the machine.
Currently, we can work at controlled pressure and temperature, eliminating trapped air and offering high reproducibility in manufacturing processes due to modern instrumentation and electronics.
There are different types of extruders, mainly differentiated by screws, double screws, or even multiple screws. The diameter and the extrusion capacity in kg/h are differentiating elements of these machines too.
In short, the rotation of the screw pushes the thermoplastic through the cylinder surrounded by thermal resistance to raise it to the necessary fusion temperature for each material. Part of this heat is also generated by friction within the cylinder and increased pressure when it reaches the exit point through the die (tooling).
Currently, several extruders can be used to coextrude different raw materials into the same part.
In the next article, we will see what auxiliary machinery is necessary to operate a complete extrusion line.