Die Casting Glossary of Terms

Die casting is a manufacturing process
Automation – Industry term commonly used to describe the mechanization of various aspects of die casting process.

Biscuit – Excess of ladled metal remaining in the shot sleeve of a cold chamber die casting machine. It is part of a cast shot and is removed from the die with the casting.

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.

Cold chamber machine – A type of die casting machine in which the metal injection mechanism is not submerged in molten metal.

Checking – Fine cracks on the surface a die which produce corresponding raised veins on die casting. Caused by repeated heating of the die surface by injected molten alloys. Also called heat checking.

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

Dimensional stability – Ability of a component to retain it’s shape and size over a long period of service.

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 pins – A rod which forces the casting out of the die cavity and off cores.

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 a sharp angle.

Flash - A thin web or fin of metal on a casting which occurs on 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.

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

Heat checking – (See checking)

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

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

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

Injection – The processes 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.

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 repeated 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.

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

Parting line - A mark left on 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.

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 – The 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 a die arranged to move parallel to die parting. The inner and 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 portion of the die.

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 though which water is circulated to cool a casting die.
Kinetic Die Casting, an American Die Casting Company