What is the process of injection filling?

The injection filling process is the process in which the pre-molded melt in the metering chamber is injected into the mold cavity. This is the process in which the polymer melt flows through the nozzle, runner and gate to the mold cavity. From the point of view of the process procedure It is divided into two stages, the injection molding stage and the pressure holding stage. Although these two stages belong to the melt flow process, the flow conditions are quite different.



The injection molding stage starts from the screw advancing the melt until the melt fills the cavity. During injection, the pressure established by the melt at the screw head is called the injection rate, and the stroke of the screw advancing the melt is called the injection stroke. The body speed performance is the main one, and enough speed head and pressure head must be established to fill the cavity.



The pressure holding stage starts from the melt filling the mold cavity until the gate is frozen. After the injection molding stage is completed, the injection pressure must continue to be maintained to maintain the shrinkage flow of the melt until the gate is frozen. The characteristic is that the pressure performance is the main, the injection pressure in the holding pressure stage is called the holding pressure, under the action of the holding pressure, the melt in the mold cavity is cooled, fed and further compressed and densified.