Injection molding is a specific cycle. There are five elements that affect injection molding: temperature, speed, pressure, position, and time, and these five process elements determine the quality of the injection molding process. Most of the quality problems frequently encountered in injection molding process are caused by the abnormal quality caused by the failure to control the five points. Temperature is the primary factor in injection molding. Temperature can be divided into several key factors: drying temperature, material temperature, mold temperature, etc. Drying temperature for the plastic material pre-drying to ensure its molding quality, to ensure that the dry plastic wetness within a certain range; material temperature for the normal plasticization of plastic and smooth filling, molding; mold temperature for the injection molding process to take into account the important factors, injection mold temperature, the size of the temperature, appearance, molding cycle and other factors affect the cooling rate of the product in the mold cavity and the appearance of the product quality. The second element speed: speed is divided into injection mold speed, molten material temperature, rejection speed, mold opening and closing speed, ejector forward and rejection speed. The increase in injection speed affects the increase in mold pressure, improve the speed of injection molding process can improve the flow rate, product quality uniformity, to ensure product quality, high-speed injection is suitable for long process products, low speed to control the size of the product injection speed affects the plasticizing ability, is an important parameter of plasticization quality, the higher the speed, the higher the temperature of the melt, the stronger the plasticizing ability of the loosening speed in order to reduce the melt specific volume, reduce the internal pressure of the melt to prevent its outflow of the opening and closing speed is an important condition to ensure mechanical operation. The third element is pressure: pressure is divided into injection pressure, holding pressure, back pressure, clamping pressure, mold protection pressure, ejector pressure. Injection pressure is used to ensure the melt from the nozzle - runner - gate - pressure loss in the cavity to ensure that the cavity is full; pressure-holding method is used to reduce the parts due to excessive injection pressure and cause sticky mold rupture or bending; being pressure method is used to avoid the mold in the high-speed high-pressure state of foreign objects and make the mold rupture; ejector pressure method is used to prevent the products out of the mold surface and make the mold damage.