The injection rate of molten material from the nozzle toemissions per unit time, the theoretical value is the product ofthe machine barrel cross-sectional area and speed. Therequirements of injection molding process of injection rate tends to not only numerical must be high, but also in the injection process of program design (i.e. grade injection). According to the specific characteristics of the use of plastic raw materialsand processing products, realize the effective control of the flow state of melt filling.