Single-acting piston extruder

Fig. 1 Single-acting piston extruder, the so-called running-out machine or stupids , from 1810).

Plastication. First, the thermoplastic resin is fed from a hopper into the barrel of a single screw extruder in which the resin is softened (or plasticized) by the action of the rotating screw. Injection. The molten polymer is forced through a nozzle by the forward action of either a piston or the screw itself acting as a piston. The resin enters through the nozzle and a series of channels, the mnners, a number of cavities in a colder mold. It should be noted that in the case of thermoset injection, the mold will be hotter than the injected resin. 

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