According to whether the injection seat retreats before and after pre-plastic feeding, that is, whether the nozzle leaves the mold, injection molding machines generally have three options.

(1) Fixed feeding: The nozzle is always stuck into the mold before and after pre-plasticizing, and the injection seat does not move.

(2) Front feeding: the nozzle is pressed against the mold for pre-plastic feeding. After the pre-molding is completed, the injection seat will move back and the nozzle will leave the mold. Choose this way

The purpose is to use the injection hole of the mold to resist the nozzle during pre-molding to prevent the melt from flowing out of the nozzle when the back pressure is high. After pre-molding, it can prevent the nozzle and the mold from contacting for a long time to generate heat transfer and affect the relative stability of their respective temperatures. .

(3) Post-feeding: After the injection is completed, the injection seat moves backwards, the nozzle leaves the mold and then preforms, and the injection seat advances after preforming. This action is suitable for processing plastics with a particularly narrow molding temperature. Since the contact time between the nozzle and the mold is short, the loss of heat and the solidification of the melt in the nozzle hole are avoided.