Nihon-yuki sticks to the screw design which is suitable for the raw material and continues to challenge raw materials to be developed one after another. Also, the unit of vent injection molding being noted is supplied by us. The experience and experience of many years of screw production, many vent remodeling requests and the merrit of vents considered, the development of a vent type injection molding machine plasticizing unit was not hesitated.　"Hungry feeder" was developed using a feeder mounted on the "SR RUDER · BAMBI" repaireting device of excess material on molding process. Abnormal wear and vent-up under the cylinder hopper can be alleviated by using this. In addition, the effect of screw design also affects vent-up. In this report, the history of vent injection molding will be explained.