Working Principle of Injection Molding Machine Barrel

The material barrel of an injection molding machine is one of the core components in the plastic plasticization and injection molding process. Its working principle mainly relies on the synergistic effect of the screw and the material barrel, which achieves the transformation of plastic from solid particles to a uniform molten state through heating and shearing.

Basic working principle

Accommodation and Heating: The material barrel is a cylindrical metal structure with heating coils (such as resistors or electromagnetic induction heating) installed inside to externally heat the plastic raw materials.

Screw rotation drive: The screw rotates inside the material barrel, conveying the plastic particles entering from the feeding port forward.

Friction and shear heat generation: Plastic is subjected to strong friction and shear between the inner wall of the barrel, the screw edges, and its own particles in the screw groove, generating a large amount of internal friction heat to assist melting.

Three stage plasticization process:

Feeding section (solid conveying section): Plastic is transported and compacted in solid form by screws.

Compression section (melting section): The depth of the screw groove becomes shallower, and the plastic is compressed, sheared, and gradually melted.

Homogenization section (metering section): The melt is further mixed and homogenized to ensure uniform temperature and viscosity, preparing for quantitative injection.

The plasticized melt is stored at the front end (storage area) of the barrel. When injected, the screw stops rotating and moves axially forward, like a plunger, injecting the melt at high speed into the closed mold through the nozzle.