Working principle of injection molding machine

- 2021-07-14-

Injection molding machine is also called injection machine, which is the main molding equipment that uses plastic molding molds to make thermoplastic or thermosetting plastics into various shapes of plastic products. Including vertical, horizontal, and all-electric. The injection molding machine can heat the plastic and apply high pressure to the molten plastic to inject it to fill the mold cavity.

The injection molding machine and the syringe used for injection have a relatively similar working principle. It is a process in which the plasticized molten state (ie, viscous flow state) plastic is injected into the closed mold cavity by the thrust of the screw (or plunger), and the product is obtained after solidification and shaping.

First, add granular or powdered plastic into the barrel of the injection molding machine. The plastic is melted by the rotation of the screw and the outer wall of the barrel. Then the machine closes the mold and moves the injection seat forward, and the nozzle is close to the gate of the mold. , And then pass the pressure oil through the injection cylinder and push the screw forward. Thus, the molten material is injected into the closed mold with a lower temperature at a high pressure and a faster speed. After a certain period of time and pressure holding (also called pressure holding), cooling, solidification and molding, the product can be opened and the product can be taken out. (To ensure that the product has a certain density and dimensional tolerances, it is the purpose of maintaining pressure to supplement the material in the cavity to avoid the reflux of the melt in the cavity). Plasticization, injection and molding are the basic requirements of injection molding. The prerequisite for the quality of the formed product to be achieved and guaranteed is plasticization, and there is a high pressure response in the cavity (20-45MPa is usually the average pressure in the cavity), so the injection molding machine has enough Large clamping force. It can be seen that the injection device and clamping device of the key part of the injection molding machine.