An injection molding machine (injection molding machine) has two basic components: an injection device and a mold clamping device for melting and feeding plastic into a mold. The role of the mold device is to: 1. Close the mold under conditions that withstand the injection pressure; 2. Remove the product from the injection device before the plastic is injected into the mold, and then control the pressure and speed to inject the melt into the mold. Currently used injection devices have two designs: screw-type pre-plasticizers or two-stage devices, and reciprocating screws. The screw-type pre-plasticizer uses a pre-plasticizing screw (first stage) to inject the molten plastic into the injection rod (second stage).
Screw pre-plasticizers have the advantages of constant melt quality, high pressure and high speed, and precise injection volume control (using mechanical thrusters at both ends of the piston stroke). These strengths are needed for transparent, thin-walled products and high production rates. Disadvantages include uneven residence time (resulting in material degradation), high equipment costs and maintenance costs.
The most commonly used reciprocating screw injection device does not require a plunger to melt and inject the plastic.