A plasticizing unit for a molding machine includes a plasticizing screw arranged in a barrel so as to be rotatably driveable, and the screw is configured to plasticize a material. A feeding device is arranged on a lateral surface of the barrel, and the feeding device is configured to feed the material to be plasticized into the barrel. A dividing device divides the feeding device into two sub-regions. A first sub-region is configured to feed the material to be plasticized into the barrel, and a second sub-region is fluidically connected to a degassing device and/or an opening along the longitudinal axis of the barrel at one end of the barrel, through which opening the plasticizing screw is inserted into the barrel, is fluidically connected to the degassing device. The degassing device is configured to discharge gases generated during the plasticization of the material to be plasticized from the barrel.

An injection molding system and method of operating the system are disclosed. The system may include a hopper, a barrel configured to receive injection material from the hopper, a screw disposed within the barrel, and a mold defining a mold cavity configured to receive the injection material from the barrel. A pressure-balancing conduit may connect the mold cavity and a rear end of the barrel and be configured to allow air to flow from the mold cavity to the rear end of the barrel. A mold valve may be disposed between the pressure-balancing conduit and the mold cavity and a barrel valve may be disposed between the pressure-balancing conduit and the rear end of the barrel. The method may include opening the mold valve and injecting a material into the mold cavity from the barrel.