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The molding of injection molded parts relies on the collaborative cooperation of injection molding machines and molds. Injection molding, also known as injection molding, belongs to the mainstream molding process of thermoplastic plastics (thermosetting plastics can also be achieved through injection molding machines). The core is to melt the plastic raw materials from solid to viscous state, fill them into the mold cavity through high pressure, and then cool and solidify to restore the shape of the mold cavity. The entire process can achieve automated continuous production, and a single cycle only takes a few seconds to a few minutes. The specific standard process is divided into six steps:
1. Raw material pretreatment: Drying and removing impurities from plastic particles (mainstream raw material forms) to remove moisture from the raw materials (to avoid bubbles and silver lines after molding). Some raw materials need to be colored, added with additives (anti-static, flame-retardant, toughening, etc.), and mixed evenly;
2. Melting plasticization: The pre treated raw materials are added to the hopper of the injection molding machine and transported to the material cylinder through the rotation of the screw. The material cylinder is heated externally (150-350 ℃, adjusted according to the material) and the screw shear friction heat is used to melt the solid particles into a uniform viscous plastic melt without clumping or bubbles;
3. High pressure injection: The screw of the injection molding machine pushes the melt, which is filled into the closed mold cavity at high pressure and high speed (usually 50-200MPa injection pressure) through the nozzle and pouring system (main channel, diversion channel, gate), filling all corners of the cavity (including fine structures);
4. Pressure retention and shrinkage compensation: After the melt fills the mold cavity, maintain a certain pressure to continue adding material to the mold cavity to compensate for the volume shrinkage during the cooling process of the plastic melt, and prevent shrinkage marks, dents, and insufficient size of the product;
5. Cooling and shaping: The mold is cooled by circulating cooling water/oil, rapidly cooling the melt in the mold cavity to below the glass transition temperature, and solidifying the melt into a solid product that conforms to the shape of the mold cavity;
6. Demoulding and component retrieval: The mold is separated from the fixed mold, and the molded injection molded part is ejected from the mold cavity through an ejection mechanism, completing one molding cycle. After the mold is closed, it enters the next cycle.