The molding process is an important part of the plastic molding process, about 30% of the plastic raw materials are used for injection molding, and the injection molding machine accounts for about 40% of the total output of plastic machinery. Injection mold is a tool for the production of plastic products, which is composed of several groups of parts, and this combination has a molding cavity. During injection molding, the mold is installed on the injection molding machine. The plastic melted into liquid is injected into the molding cavity, and cooled in the cavity, and then the upper and lower molds are separated through the ejection system to eject the plastic product from the mold cavity. Injection molding is a cyclic process, and the completion of injection molding needs to go through three stages: pre-molding, injection molding and cooling. 
(1) Pre-plastic stage; The screw begins to rotate, and then the plastic transported from the hopper to the front end of the screw, plastic under the action of high temperature and shear force plasticized uniformly and gradually gathered in the front end of the barrel, with the accumulation of molten plastic, the pressure is increasing, and finally overcome the back pressure of the screw gradually pushed back, when the plastic in the front of the material reaches the required amount of injection molding, the screw stops backward and rotating. The premolding phase is over. (2) Injection molding stage; The screw moves forward under the action of the injection cylinder, pushing forward the plastic stored in the front of the material sheet at multiple speeds and pressures, and injecting it into the closed mold cavity through the runner and gate. (3) cooling and shaping stage; The plastic passes through the pressure holding in the mold cavity to prevent the plastic backflow until the plastic cures and the pressure in the mold cavity disappears. The proportion of cooling setting time in each production cycle is the largest. The injection molding process is a periodic cycle process, and the mold is closed and filled to maintain pressure in each cycle. Operation such as cooling mold opening and ejecting products. Among them, injection molding (melt filling) pressure holding and cooling are the three key bad joints that are related to the smooth molding. However, the flow behavior and filling characteristics of the melt are closely related to the pressure and speed of the filling and the temperature of the body, so understanding the flow behavior and other related characteristics of the melt is of great significance for the design of the entire injection molding process. BHC precision is a professional plastic mold manufacturer, providing mold design, manufacturing, mold assembly, mold trial, injection molding to the complete set of services, providing ordinary injection molding and 100,000 clean injection molding processing, welcome to consult.
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