There are three feeding methods for standard vertical injection molding machines: front feeding, rear feeding and fixed feeding. Generally, the appropriate feeding method is selected according to the nozzle and material conditions.
1. Pre-feeding: After each injection is completed, after the plasticization reaches the pre-plasticization requirements, the injection seat moves backward, and then advances until the next working cycle, so that the nozzle contacts the mold for injection. This method is used in situations where the nozzle temperature is difficult to control, the back pressure is high, and backflow is prevented.
2. Post-feeding: After the injection is completed, the injection seat is retracted and then pre-plasticized. When the next working cycle starts, the injection seat is moved forward for injection. This method is used to control the nozzle temperature and process clean plastic.
3. Fixed feeding: During the entire injection molding process, the nozzle and the mold are kept in contact. This method is suitable for the case where the nozzle temperature is easy to control and the temperature range of plastic molding is wide.