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Common Die Casting Terms

Die Casting

Ageing - A change in the metallurgical structure of an alloy occurring over a period of time following casting, affecting material properties and component dimensions. It is accelerated by moderate heating.

Alloy - A substance having metallic properties and composed of two or more chemical elements, of which at least one is a metal.

Alloy, primary - Any diecasting alloy whose major constituent has been refined directly from ore, not recycled scrap metal.

Alloy, secondary - Any diecasting alloy whose major constituent is obtained from recycled scrap metal.

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

Barrel plating - A plating process in which parts are processed in bulk in a rotating container.

Biscuit - Excess of ladled metal remaining in the shot sleeve of a cold chamber diecasting machine. It is part of the cast shot and is removed from the die with the casting. Also known as the slug.

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

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

Casting rate - The average number of shots that can be cast during one hour of steady running.

Cavity fill time - The period of time required to fill the cavity with metal after the metal begins to enter the cavity.

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

Chromate - A conversion coating consisting of trivalent and hexavalent chromium compounds.

CNC - Computer Numerical Control is a system that uses a dedicated computer as the machine control unit.

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

Combination die - A die with two or more different cavities each producing a different part.

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

Core, fixed - A core that, as the die opens and closes, does not move relative to the cavity block into which it is mounted.

Core, moving - >A core which must move through some travel as the die opens or immediately after the die has opened, to allow the unrestricted ejection of the casting.

CPM - Cycles Per Minute, denoting the speed of a diecasting machine in terms of the number of shots (which may be of multiple cavities) produced per minute.

Creep - The continuing deformation of a material over time when subjected to a constant stress, dependent on both temperature and initial stress.

Crucible - The vessel in which metal alloy is melted.

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

Die block - The large block of steel that forms the base for one half of a diecasting die. All other components of the die are attached to or mounted on the die block.

Die cast skin - The metal on the surface of a diecasting which is approximately 0.8mm thick and is characterized by a fine grain structure and freedom from porosity.

Die insert - A removable liner or part of a die body.

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

Die release - A coating which improves casting surface quality and which facilitates removal of the casting from the die.

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 alignment 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.

EDM - Spark erosion or Electrical Discharge Machining is a process to remove metal using sparks. In this process, a shaped electrode creates a cavity, which is a mirror image of the electrode.

Ejector marks - Marks left on castings by ejector pins.

Fatigue - The phenomenon, leading to fracture under repeated or fluctuating stresses, that has 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 the molten metal is injected into the die.

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.

Flow Analysis - A computer simulation to model how molten metal flows, cools and solidifies in a die.

Furnace - The vessel in which metal alloy is melted.

Galling - Tearing out of particles from a metal surface caused by sliding friction.

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

Gate erosion - Die damage induced by the long-term high temperature and high velocity stream of metal entering the cavity.

Gooseneck - Spout connecting a metal pot or chamber with a nozzle or sprue hole in the die, 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 diecasting machine.

Heat checking - (See Checking)

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

HSM - High-Speed Milling removes die steel using high spindle speeds and rapid surface feeds. It is an alternative to EDM.

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 diecasting.

Laser Milling - A tool fabrication technique removing die steel using laser beams.

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

Multiple/multi 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 diecasting 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.

Pot - The vessel in which metal alloy is melted.

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 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.

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

Stability, dimensional - (See Dimensional Stability)

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 diecasting.

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

Undercut - Recess in the side wall, or cored hole of a casting, to hold the casting during the opening of the dies. 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 line, 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.

Wire EDM - Similar to Electrical Discharge Machining, but using a wire electrode, as a jigsaw, to create linear features through steel.

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

This technical information has been contributed by
Deco Products Company

Click on Company Name for a Detailed Profile

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