Abstract: A method for determining an actual volume Vr of an injection-moldable compound during an injection-molding process is disclosed. The injection-moldable compound is introduced into at least one cavity of the mould. The method includes the steps of: a) determining a theoretical volume Vt from process variables at least during a filling phase of the injection-molding process, b) determining and/or measuring at least one value for at least one compound pressure pM, c) selecting a material-specific compression k (p), corresponding to the value of pM, of the injection-moldable compound, and d) calculating an actual volume Vr by taking into account the compression k (p).

Abstract: In a method for operating an injection moulding machine in the absence of a backflow barrier, plastic melt is injected by a plasticising device into a cavity in a screw antechamber of a plasticising screw adapted to rotate about a longitudinal axis and to move translationally by a drive unit during an injection phase and a holding- pressure phase. A rotational drive of the drive unit is controlled such that a speed of the plasticising screw causes overlay of a backflow of the plastic melt from the screw antechamber back into screw threads of the plasticising screw by an opposing delivery flow as a result of a rotation of the plasticising screw due to a translational injection movement of the plasticising screw. A differential flow is established from the backflow and the opposing delivery flow and influenced at least during the injection phase by influencing the speed of the plasticising screw.