A die casting machine or an injection molding machine comprises a pressure member, such as a casting piston in a shot sleeve or extruder screw in an extruder barrel. A control unit is associated to this pressure member and/or to a filling system for filling the shot sleeve or the barrel. Moreover, an evacuation device is provided which includes a vacuum valve that communicates with the cavity of the die or mold, on the one hand, and a vacuum conduit on the other hand. This vacuum valve may be moved from an open position interconnecting the cavity and the vacuum source, and a closed position. There is a control connection between the control unit and the valve. The positions of the valve can be controlled by a material sensor located in its region and associated to it, the sensor supplying a closure signal to the valve through an output line. This output line, however, is also coupled to the control unit for influencing and controlling at least one of its controlled parts, i.e. pressure member and/or filling system.