FAQ - 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. 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, 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.