The injection unit of injection molding machine is much like an extruder. The injection unit melts the polymer resin and injects the polymer melt into the mold. It consists of a barrel that is fed from one end by a hopper containing a supply of plastic pellets. The unit may be: ram fed or screw fed.
The injection unit consists of a granulate hopper, cylinder, screw, nozzle, heating bands and hydraulic drives and serves the purpose of melting and injecting the moulding material.
The reciprocating-screw machine is the most common. This design uses the same barrel for melting and injection of plastic.
The alternative unit involves the use of separate barrels for plasticizing and injecting the polymer. This type is called […]