Working Principle Of Injection Molding Machine

The working principle of an injection molding machine is similar to that of a syringe used for injection. It uses the thrust of a screw (or plunger) to inject the melted plastic (i.e. viscous flow) that has already been plasticized into a closed mold cavity, and then solidifies to obtain the product.
Injection molding is a cyclic process, which mainly includes: quantitative feeding, melting and plasticizing, pressure injection, mold filling and cooling, and mold opening and picking up. After removing the plastic part, close the mold again and proceed to the next cycle.
Injection molding machine operation project: The injection molding machine operation project includes three aspects: control keyboard operation, electrical control system operation, and hydraulic system operation. Select the injection process action, feeding action, injection pressure, injection speed, and ejection type separately, monitor the temperature of each section of the material barrel, and adjust the injection pressure and back pressure.
The molding process of a general screw injection molding machine is as follows: first, granular or powdered plastic is added to the barrel, and the plastic is melted through the rotation of the screw and the heating of the outer wall of the barrel. Then, the machine closes the mold and moves the injection seat forward to make the nozzle close to the gate of the mold. Then, pressure oil is introduced into the injection cylinder to push the screw forward, Thus, the molten material is injected into a closed mold with a low temperature at a high pressure and a fast speed. After a certain period of time and pressure maintenance (also known as pressure maintaining) and cooling, the product can be solidified and formed. The purpose of pressure maintaining is to prevent the reverse flow of molten material in the mold cavity, replenish material into the mold cavity, and ensure that the product has a certain density and dimensional tolerance. The basic requirements for injection molding are plasticization, injection, and molding. Plasticization is a prerequisite for achieving and ensuring the quality of molded products, and in order to meet the requirements of molding, injection must ensure sufficient pressure and speed. At the same time, due to the high injection pressure, a corresponding high pressure is generated in the mold cavity (the average pressure in the mold cavity is generally between 20 and 45 MPa), so there must be sufficient clamping force. It can be seen that the injection device and clamping device are key components of the injection molding machine.
There are three main aspects to evaluate plastic products. The first is the appearance quality, including integrity, color, gloss, etc; The second is the accuracy between size and relative position; The third is the physical, chemical, and electrical properties corresponding to the purpose. These quality requirements vary depending on the usage occasion of the product and the required scale. The defects of the product mainly lie in the design, manufacturing accuracy, and wear degree of the mold. But in fact, the technical personnel of plastic processing plants often face the difficult situation of using process methods to compensate for the problems caused by mold defects without achieving much success.