To set the dwell time for the molding conditions of plastic injection molding, it need to know the gate time. The weight of the molded product becomes heavier if pressure is applied until the gate seal, and after the gate seal, the molten resin does not enter the mold cavity even if the dwell time is extended, so the weight of the molded product does not increase and remains constant. From these relationships, it is possible to know the gate sealing time by applying the dwell time until the product weight no longer changes.
If the dwell time is longer than the gate seal time, the weight of the molded product is constant and there is no change in the weight. If the dwell time is shorter than the gate seal time, the weight of the molded product changes. If the variation of this change is large, it can be said that the dwell time is desirable to be longer than the gate seal time in consideration of stable molding.
However, since the extending the dwell time to the gate seal time also extends the molding cycle, it is required to determine the dwell time in consideration of the quality requirements and cycle cost of the molding product after determining the quality variation of the molding product under each dwell time.