In core pull technology, the cavity is first completely filled and the part is subjected to melt back pressure (FIgura 10.24a). Before or during the introduction of the gas, an additional displaced volume is created in the main cavity by the withdrawal of one more the cores (Figure 10.24b).
In core pull technology, work also proceeds with an open nozzle. The core is inserted. The material is injected, and the moulded part is completely filled. The core is withdrawn from the moulder part hydraulically, this opening into the moulded part occurs simultaneously. The gas holding phase follows. The recovery of the gas follows after the gas holding phase. After the gas is sealed, the screw can begin dosing again. The process is illustrated in Figure 10.24.