Abstract: A mold assembly for use in injection molding an object having an aperture therein, includes first and second interlocking portions which are separable from each other along an axis which is perpendicular to the axis of the aperture. The aperture is formed by an elongated core which is stationarily defined on one of the mold portions and conformingly engages the other mold portion when the mold is closed. The mold portions are drawn into tight, interlocking engagement with each other by wedge-shaped surfaces adjacent the core and respectively defined on the mold portions, thereby preventing flashing from forming over the aperture during the molding process.