Plastic injection molding process
Plastic injection molding process
1. Clamping process. The pressure oil in the mold clamping cylinder pushes the moving platen forward to close the mold. Among them, the mold is first closed at low pressure and high speed; when the moving platen is about to approach the fixed platen, it is switched to low pressure and closed at low speed (mold protection); when it is confirmed that there is no foreign matter in the mold, it is switched to high pressure (clamping force), and lock the mold.
2. The injection table and the material injection process. After the mold is locked with the clamping force, the nozzle and the mold fit together in the injection stage. After the injection solenoid valve is energized, the injection cylinder is filled with pressure oil, pushes the screw connected to the piston rod of the cylinder, and injects the molten material in the barrel into the locked cavity according to the graded pressure and speed.
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3. Pressure-holding process. During the process of filling the mold cavity with the melt until it is filled, the screw is required to maintain a certain pressure on the melt to prevent the melt in the mold from flowing back; The required materials to avoid defects such as shrinkage holes in the products.
4. Cooling and pre-molding process. Once the gate is sealed, the pressure-holding process is cancelled, and the product is naturally cooled and shaped in the mold; at the same time, the pre-plastic oil motor is driven to rotate the screw, and the granular plastic from the hopper is transported forward for plasticization. After the plasticization of the raw material reaches a predetermined metering value, in order to prevent the melted plastic from overflowing the nozzle, the screw needs to be moved backward for a certain distance, that is, the saliva treatment is performed.
5. The ejection table is withdrawn, the mold is opened and the product is ejected. After the pre-plastic measurement is completed, in order to prevent the nozzle from contacting the cold mold for a long time to form a cold material, etc., it is usually necessary to withdraw the nozzle from the mold, that is, enter the injection table retreat condition. Whether the action is executed and the sequence of execution can be selected. Once the product is cooled and shaped, the mold is opened and the product is automatically ejected.