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The thoery of injection machining
Jan 16, 2019

The working principle of the injection moulding machine is similar to that of the injector used for injection. It is a process of injecting the graininess of plasticized metal material (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 cyclic 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.

 Injection Molding Machine Operating Project: Injection Molding Machine Operating Project includes control keyboard operation, electrical control system operation and hydraulic system operation. The selection of injection process action, feeding action, injection pressure, injection speed, ejection type, temperature monitoring of each section of the barrel, injection pressure and back pressure adjustment are carried out respectively.

 Generally, the forming process of screw injection moulding machine is as follows: firstly, the granular or powdery plastic is added into the barrel, and then the plastic is melted by the rotation of the screw and the heating of the outer wall of the barrel. Then the machine closes the mould and moves the injection seat forward to make the nozzle close to the gate of the mould, and then the injection cylinder is injected with pressure oil to push the screw forward with high pressure and speed. The speed will inject the melt into the closed die with lower temperature, after a certain period of time and pressure (also known as holding pressure) and cooling to make it solidified, the product can be removed from the open die (holding pressure is designed to prevent the reflux of the melt in the die cavity, to supplement the material to the die cavity, and to ensure that the product has a certain density and size tolerance). The basic requirements of injection moulding are plasticization, injection and moulding. Plasticization is the precondition to realize and guarantee the quality of moulded products. In order to meet the requirements of moulding, injection must ensure sufficient pressure and speed. At the same time, due to the high injection pressure, the corresponding high pressure in the cavity (the average pressure in the cavity is usually between 20 and 45 MPa), so it must have enough clamping force. Therefore, injection device and clamping device are the key parts of injection moulding machine.


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