Injection molding processing methods for thermoplastic plastics

Thermoplastic injection molding is a method of melting plastic materials and injecting them into the membrane cavity.
Once molten plastic enters the mold, it is cold formed into a certain shape according to the mold cavity sample. The resulting shape is often the final product, and no further processing is required before installation or use as the final product. Many details, such as protrusions, ribs, and threads, can be formed in one step of injection molding.
The injection molding machine has two basic components: an injection device for melting and feeding plastic into the mold, and a clamping device. The function of the mold closing device is to: 1. make the mold close under the pressure of injection; 2. Remove the product from the injection device and melt it before injecting the plastic into the mold. Then, control the pressure and speed to inject the melt into the mold.
There are currently two designs of injection devices used: screw type pre plasticizer or two-stage device, and reciprocating screw. The screw type pre plasticizer utilizes the pre plasticizing screw (first stage) to inject molten plastic into the injection rod (second stage).
The advantages of a screw pre plasticizer are constant mass of molten material, high pressure and speed, and precise injection volume control (utilizing mechanical thrust devices at both ends of the piston stroke). These strengths are required for transparent, thin-walled products, and high production rates. Its drawbacks include uneven residence time (leading to 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 plastic.