Glossary A-CC-CD-EF-GG-II-MN-PP-SS-SS-TT-VW Trim die a die for removing flash from a die casting. Undercut recess in the side wall or cored hole of a casting disposed so that a slide or special form of core (such as a knockout) is required to permit ejection of the casting from the die. Unit die a die interchangeable with others in a common holder. Vent narrow passage at the die parting which permits air to escape from the die cavity as it is filled with molten metal. Void a large pore or hole within the wall of a casting usually caused by an entrapped gas. A blowhole.