The working principle of injection machine is similar to that of the syringe used for plastic. It is a process of injecting the plasticized melt state (i.e. viscous flow state) into the closed cavity with the help of the screw (or plunger) to obtain the product after solidification and shaping.

Injection molding is a cycle process, each cycle mainly includes: quantitative feeding - melt plasticization - pressure injection - filling cooling - opening parts. After removing the plastic parts, the mould is closed again for the next cycle.