Glossary of Die Cast Terms

Automation - Industry term commonly used to describe the mechanization of various aspects of the die casting process.

Blister - A surface bubble caused by gas expansion (usually from heating) which was trapped within the die casting or beneath the plating.

Blow holes - Voids or pores which may occur due to entrapped gas or shrinkage during solidification, usually evident in heavy sections (see porosity).

Cavity - The recess or impressions in a die in which the casting is formed.

Checking - Fine cracks on the surface of a die which produce corresponding raised veins on die castings. Caused by repeated heating of the die surface by injected molten alloys.

Creep - Plastic deformation of metals held for long periods at stresses lower than yield strength.

Die lubricant - Liquid formulations applied to the die to facilitate casting release and prevent soldering.

Dimensional stability - Ability of a component to retain its shape and size over a long period in service.

Dowel pin - A guide pin which assures registry between cavities in two die halves.

Draft - The taper given to walls, cores and other parts of the die cavity to permit easy ejection of the casting.

Ejector marks - Marks left on castings by ejector pins.

Ejector plate - A plate to which ejector pins are attached and which actuates them.

Fillet - Curved junction of two surfaces, e.g., walls which would meet at a sharp angle.

Flash - A thin web or fin of metal on a casting which occurs at die partings, vents and around moveable cores. This excess metal is due to working and operating clearances in a die.

Gate - Passage for molten metal which connects runner with die cavity. Also, the entire ejected content of a die, including castings, gates, runners, sprue (or biscuit) and flash.

Gooseneck - Spout connecting a metal pot or chamber with a nozzle or sprue hole in the die and containing a passage through which molten metal is forced on its way to the die. It is the metal injection mechanism in a hot chamber type of die casting machine.

Growth - Expansion of a casting as a result of aging or of intergranular corrosion, or both.

Heat checking - (See checking)

Hot chamber machines - Die casting machines which have the plunger and gooseneck (metal pressure chamber) immersed in molten metal in the holding furnace.

Hot short - Term used to describe an alloy which is brittle or lacks strength at elevated temperatures.

Impact strength - Ability to resist shock, as measured by a suitable testing machine.

Impression - Cavity in a die. Also, the mark or recess left by a ball, or penetrator of a hardness tester.

Ingot - Metal or alloy cast in a convenient shape for storage, shipping and remelting.

Injection - The process of forcing molten metal into a die.

Insert - A piece of material, usually metal, which is placed in a die before each shot. When molten metal is cast around it, it becomes an integral part of the die casting.

Intergranular corrosion - A type of corrosion which preferentially attacks grain boundaries of metals or alloys, resulting in deep penetration.

Loose piece, knockout - A type of core (which forms undercuts) which is positioned in, but not fastened to a die. It is so arranged as to be ejected with the casting and from which it is removed. It is used repeatedly for the same purpose.

Metal saver - Core used primarily to reduce amount of metal in a casting and to avoid sections of excessive thickness.

Multiple cavity die - A die having more than one duplicate impression.

Nozzle - Outlet end of a gooseneck or the tubular fitting which joins the gooseneck to the sprue hole.

Overflow-well - A recess in a die connected to a die cavity by a gate to assist in proper venting.

Parting line - A mark left on a die casting where the die halves meet; also, the mating surface of the cover and ejector portions of the die.

Plunger - Ram or piston which forces molten metal into a die.

Port - Opening through which molten metal enters the injection cylinder.

Porosity - Voids or pores resulting from trapped gas, or shrinkage during solidification.

Process control - Where parameters of a process are studied and correctly applied in the manufacturing process to produce high quality parts.

Runner - Die passage connecting sprue or plunger holes of a die to the gate where molten metal enters the cavity or cavities.

Shot - That segment of the casting cycle in which molten metal is forced into the die.

Shrinkage, solidification - Dimensional reduction that accompanies the freezing (solidification) of metal passing from the molten to the solid state.

Shrink mark - A surface depression which sometimes occurs next to a heavy section that cools more slowly than adjacent areas.

Slide - The portion of the die arranged to move parallel to die parting. The inner end forms a part of the die cavity wall that involves one or more undercuts and sometimes includes a core or cores.

Soldering - Adherence of molten metal to portions of the die.

Split gate - A gate of castings having the sprue or plunger axis in the die parting.

Sprue - Metal that fills the conical passage (sprue hole) which connects the nozzle with runners.

Sprue pin - A tapered pin with rounded end projecting into a sprue hole and acting as a core which deflects metal and aids in the removal of the sprue.

Toggle - Linkage employed to mechanically multiply pressure when locking the dies of a casting machine.

Trim die - A die for shearing or shaving flash from a die casting.

Unit die - A die interchangeable with others in a common holder.

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.

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 entrapped gas. A blow hole.

Waterline - A tube or passage through which water is circulated to cool a casting die.