Abstract: An injection method for making a hole in an injection molded plastic article comprising the steps of filling a mold cavity with a molten plastic and cooling the mold to effect gate seal. A first hole-making punch and a second punch, which are slidably inserted in a bore provided in the mold coinciding with the hole to be made in the article in an axial direction in which a movable mold half is opened and closed, are vibrated with high frequency after gate seal is completed to soften the solidified plastic between the two punches. The punches are then displaced with respect to the bore when the plastic is softened to make the hole. A second injection method comprises the step of making the hole in the molded article by sliding the punches during both dwelling and cooling subsequent to the completion of dwelling after filling the mold with the molten plastic and before gate seal is effected.

Abstract: A method for degating an injection molded plastic article includes the steps of filling a mold cavity with a molten plastic, dwelling and cooling the mold subsequent to filling to effect gate seal. A first degating punch and a second punch are provided slidably inserted in holes in the mold which cross a gate in an axial direction, being the direction in which a movable mold half is opened and closed. The punches are vibrated at a high frequency after gate seal is completed in order to soften the solidified plastic in the gate. The punches are then displaced with respect to the gate when the plastic is softened in order to effect degating. In another method, a step of cutting the gate in the molded article by sliding the punches occurs during both dwelling after filling the mold with the molten plastic, and cooling subsequent to the completion of dwelling, and before gate seal is effected.