Glossary of Die Casting Terms

(courtesy NADCA)

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Die, Trim. A die, usually in a power press, that cuts the runners, overflows, and flash off the die casting.
Die, Unit. A type of die construction that allows quick changing of the cavity blocks in the holder or die block. This usually can be performed while the die is still in the machine.
Dimension, Critical. A dimension on a part that must be held within the specified tolerance for the part to function in its application.
Draft. A slight angle placed on surfaces that would otherwise be parallel to the direction in which the die opens. The draft allows that surface to move away from the cavity wall as the casting is
removed from the die.
Eject. To push the solidified casting out of the cavity of the die casting die.
Ejector. A pin or mechanism that pushes the solidified die casting out of the die.
Flash. A thin web or fin of metal on a casting which occurs at die parting, air vents, and around movable cores. This excess metal is due to the necessary working and operating clearances in a die.
Gate. A thin passage for molten metal which connects the runner to the die cavity. Also, the entire ejected content of a die, including the castings, gates, runners, biscuit (or spue), and flash.
H-13 Steel. An air hardening hot work tool steel of fine grain structure and high cleanliness that is exclusively used for making die casting dies for casting aluminum and zinc alloys.
Hole, Cored. In a die casting, any hole that is formed by a core in the die casting die. A cored hole is distinguished from a hole that is added after the casting has been made (as by drilling).
Hot Chamber Machine. A die casting machine that has the molten metal pressure chamber immersed in the molten metal in the holing furnace.The advantage of the hot chamber machine is that the pressure chamber refills naturally after each shot is made.
Injection. The process of forcing molten metal into die casting die.
Insert, Cast-In. A piece of material, usually metal, which is placed in a die and becomes an integral part of the die casting after molten metal is cast around it.
Metal Saver. A shape made on the cavity of a die casting for the sole purpose of displacing unnecessary die casting alloy from the casting. The shape placed on the casting by the metal saver is not required for the function of the casting.
Overflow. A small reservoir cavity added to the exterior of the die cavity (on a parting line) to receive impure or cold metal during cavity fill. Also used to generate added die heat in the local area.
Parting Line. A line-like mark around a die casting where the two halves of the die came together.
Platen. A large thick flat steel plate that is a major part of a diecasting machine frame.

Porosity. Any void within a die casting that was not intentionally created. This includes such voids that are open to the surface of the casting as well as those that are completely encased within the casting.