Die Casting Glossary

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

Biscuit – Excess of ladled metal remaining in the shot sleeve of a cold chamber die casting machine. It is part of the 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 casting machine in which the metal injection mechanism is not submerged in molten metal.

Checking – Fine cracks on the surface of a die which produce corresponding raised veins on die castings. This is 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 lubricants – Liquid formulations applied to the die to facilitate casting release and prevent soldering.

Dimensional stability – The 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, spruce (or biscuit) and flash.

Gooseneck – Spout connecting a metal pot or chamber with a nozzle or spruce 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 inter-granular corrosion, or both.

Heat checking – (See checking)

Hot chamber machines – Die casting machines which have the plunger, 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 – The 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 penetration of a hardness tester.

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

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.

Inter-granular 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 spruce 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 – The 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 spruce 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 spruce or plunger axis in the die parting.

Spruce – Metal that fills the conical passage (spruce hole) which connects the nozzle with runners.

Spruce pin – A tapered pin with rounded end projecting into a spruce hole and acting as a core which deflects metal and aids in the removal of the spruce.

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. I.e. A blow hole.

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