Plastic Injection Molding Process 

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Plastic injection molding process is the primary molding method for thermoplastic materials. The process usually includes the following steps: feeding, plasticization, injection, pressure holding, cooling and ejection. Plastic pellets are fed into the injection hopper and then fall into the barrel. Inside the barrel, the rotating screw transports the pellets forward. the heating bands wrapping around the barrel warm up the plastic pallets. As the pellets are moved forward by the rotating screw, they are gradually melted, and are entirely molten when they reach the front of barrel. Once enough molten plastic is in front of screw, the screw injects the molten plastic into the mold cavity through sprue & runner system of the mold. When the molten plastic is shrinking inside the mold due to cooling, the screw will continuously force the molten plastic into the mold for replenishment, to ensure that a complete structured product is produced. The mold temperature controller delivers water or oil into the cooling system to maintain the mold temperature as specified. The molten plastic cools down and then solidifies in less than a minute. The mold opens and the ejector rod moves the ejector pins forward. The part and runner fall and are captured in a bin. After that, the whole process repeats over and over to produce more plastic products.