Casting Terminology

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A substance having metallic properties and composed of two or more chemical elements, of which at least one is metal. Alloy properties are usually different from those of the alloying elements.

To subject a metal to electrolytic action as the anode of a cell in order to coat with a protective or decorative film.

Condition of a casting that has not been given a thermal treatment subsequent to casting. This is also termed as the “F temper.”



Excess metal left at the end of the injection cylinder of a cold-chamber die casting machine, formed at the end of the plunger stroke. Also called a slug.

A surface defect or eruption caused by expansion of gas, usually as a result of heating trapped gas within the casting, or under metal which has been plated on the casting.

Blow holes
Voids or holes in a casting that may occur due to entrapped air or shrinkage during solidification of heavy sections.



The relative ease with which an alloy can be cast; includes the relative ease with which it flows and fills out a die/mould cavity, and its relative resistance to hot cracking and tearing.

The recess in the die in which the casting is formed.

Checking (Heat-checking)
Fatigue of a die surface, especially when subjected to repeated heating by molten alloys at high casting temperatures. The resulting fine cracks produce corresponding raised veins on die castings.

A conversion coating consisting of trivalent and hexavalent chromium compounds.

Cold shut 
A lapping that sometimes occurs where metal fronts join during the formation of solidified metal that sometimes occurs in the formation of die castings which constitutes an imperfection on or near the surface of the casting.

Cold-Chamber machine
A die casting machine designed so that the metal chamber and plunger are not continually immersed in molten metal.

Combination die (Family Die)
A die with two or more different cavities each producing a different part, also called a family die.

A part of a die casting that forms an internal feature of the casting (usually a feature with considerable dimensional fidelity) and is a separate piece from the cavity block. Acore may be fixed in a stationary position relative to the cavity block or may be actuated through some movement each time the die is opened.

Core pin
A core, usually of circular section. Core pins are hot work tool steel pins, usually H-13, used for a core hole in a die casting die and may be fixed or movable. A core is made from a core pin.



The removal of burrs, sharp edges or fins by mechanical, chemical electrochemical or electrical discharge means.

The bending or twisting of a die casting or a tool when a load is imposed on it. Deflection is normally used to describe elastic strain (i.e., the item will return to its original shape when the load is removed) rather than permanent (plastic) deformation.

A metal block used in the die casting process, incorporating the cavity or cavities that form the component, the molten metal distribution system and means for cooling and ejecting the casting.

Die cast skin
The metal on the surface of a die casting, to a depth of approximately 0.020 in. (0.8mm), characterized by fine grain structure and freedom from porosity.

Die life
The number of usable castings that can be made from a die before it must be replaced or extensively repaired.

Die release
Die coating to improve casting surface quality and facilitate removal from die.

Die, multiple-cavity
A die having more than one casting cavity.

Die, single cavity
A die casting die that has only one cavity.

Dimension, linear
Any dimension to features of the die casting that are formed in the same die component(half). Any straight line dimension on a part of die print.

Dimension, parting line
A dimension on a casting, or in a die casting die cavity, that is parallel to the direction of die pull and crosses the die parting line.

Draft allowance
The maximum angle of the draft that is allowed by the casting’s part print.

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



To push the solidified casting out of the cavity of the die casting die.

Ejector marks
Marks left on castings by ejector pins, frequently including a light collar of flash formed around the ejector pin.

Ejector pin
A pin actuated to force the casting out of the die cavity and off the cores.

A damaged condition in the die cavity or die runners caused by the impingement of the molten metal during injection.



The phenomenon leading to fracture under repeated or fluctuating stresses that have a maximum value less than the tensile strength of the material.

Fatigue, thermal
The cracking (or crazing) of the die cast die cavity surface. This is caused by the expansion and contraction of the outer cavity surface which happens every time molten metal is injected into the die.

Curved juncture of two surfaces; e.g., walls that would otherwise meet at a sharp corner.

Any apparatus that holds a part, such as a die castig, firmly in a predetermined position while secondary operations are being performed on the part.

Flash (metal extension)
The thin web or fin of metal on a casting occurring at die partings, air vents, and around movable cores. The excess metal is due to the working pressure and operating clearances in the die.

Flow lines
Marks appearing on the surface of a casting that indicates the manner of metal flow.



Gate erosion
Die damage induced by the long term high-temperature and high- velocity metal stream from the die inlet gate(s).

The passage connecting a runner or overflow with a die cavity. Also, the entire ejected content of a die, including the casting or castings and the gates, runners, sprue (or biscuit) and flash.

In hot-chamber die casting, a 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.



Hot-chamber machine
A die casting machine designed with the metal chamber and plunger continually immersed in molten metal, to achieve higher cycling rates.

Particles of foreign material in a metallic matrix. The particles are usually compunds(such as oxides, sulfides or silicates), but may be of any substance that is foreign to (and essentially insoluble in) the matrix.



A pig or slab of metal or alloy.

The act or process of forcing molten metal into a die.

A piece of solid material, usually metal, that becomes an integral part of the casting. Inserts are commonly set in the die so that metal is cast around that portion left exposed in the die cavity. Alternatively, inserts are often applied subsequent to casting. (Note: inserts become a part of the casting, whereas die inserts are a part of the die.)



A recess in a die, connected to a die cavity by a gate, remote from the entrance gate (ingate.)



Pre-Production Approval Process

Parting line
The junction between the cover and ejector portions of the die or mold. Also, the mark left on the casting at this die joint.

Ram or piston that forces molten metal into a die.

Voids or pores, commonly resulting from solidification shrinkage; air (primarily the nitrogen component of air) trapped in a casting or hydrogen exuded during electroplating.

The process of heating a die casting die prior to making castings to minimize the thermal shock from the first few castings. Also applied to die heating prior to die placement in the machine for more rapid die changing and onset of production.



Pressure Die Casting 
The process of taking molten metal and injecting it into a steel mould under pressure to form a "near net shape" product.  This is the most cost-effective way to produce metal parts in significant volume.  Process speed and accuracy reduce the amount of labor and added processes required while increasing product quality and consistency.

The process of smelting trimmings, scrapped parts, dross and machine turnings back to original alloy specifications.

Release agent
A material that is applied to the surface of the die cavity to keep the casting from sticking to the die. Such materials are usually applied frequently, sometimes every shot, and are usually applied by spraying. To facilitate the spray, the material is mixed with water or a mineral solvent which evaporates from the cavity surface.

A wall normal to a second wall or surface to strengthen or brace the second wall or surface.

A die passage connecting the sprue hole or plunger hole of a die to the gate or gates where molten metal enters the cavity or cavities.



Die filling or part of the casting cycle in which molten metal is forced into the die.

Shot size
The cubic volume of a die cast shot or the cubic volume of die casting alloy that a die casting machine is capable of injecting into a die. Shot sizes are sometimes expressed in weight or mass units.

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

Sleeve, shot
The molten metal chamber of a cold-chamber die casting machine. This is a hardened steel tube through which the shot plunger moves to inject the molten metal into the die.

Portion of a die generally arranged to move parallel to the parting line. The inner end forms a part of the die cavity wall and sometimes includes a core or cores.

The sticking or adhering of molten metal to portions of the die following casting.

Metal that fills the conical passage (sprue hole) that connects the nozzle or hot chamber to the runners of a hot-chamber machine. (Most cold-chamber machines form a slug and have no sprue.)



A thin narrow passage that permits air to escape from the die cavity as it is filled with metal.

Vibratory finishing
A process for deburring and finishing, mechanically by means of abrasive media in a container subjected to high-rate oscillations.

A large pore or hole within the wall of a casting usually caused by solidification shrinkage or gas trapped in the casting. Also, a blow hole.