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Die Casting

ADCI. The American Die Casting Institute, a trade association
serving the die casting industry by providing statistical,
marketing, technical, and management programs.

Alignment System. A set of pins, bushings, blocks, and wear
plates that work together and cause the two die halves to align

Alloy. A substance composed of two or more metals, or of a
metal and a non-metal. The alloy elements are dissolved in each
other when molten and fused together when a solid. Most die
castings are made from alloys.

Alloy, Certified Zinc. A program implemented by the ADCI in
which participating die casting companies regularly have their
zinc die castings tested to certify they are maintaining the correct
alloy content.

Aluminum. A light silvery metal that is used as the major
constituent in may die casting alloys.

Anodize. A chemical process using an electric current in a
solution to produce a hard and dense oxide protective surface
on a part.

As-Cast. The condition of a die casting when the runners, flash,
and overflows have been removed, but no surface finishing,
machining, or coating operations have been performed.

Auto-Ladle. A mechanical metal feeding delivery device usually
attached to a cold chamber die casting machine, or a part of a
furnace system.

Automatic Operation. An expression used to describe a die
casting machine that operates continuously without an operator
initiating each cycle, lading the molten metal, or removing the

Benching. The hand finishing of die casting die cavity surfaces.

Biscuit. The excess of ladled metal that remains in the shot sleeve
on a cold chamber die casting machine. The biscuit is part of the
cast shot and is removed from the die with the casting.

Blister. A casting defect characterized by a smooth bump on the
surface of the casting and a hole inside the casting directly below
the bump.

Blow. The physical opening of the die casting die when the
internal force of the shot exceeds the locking force of the
machine. The blow causes flash and excessive casting

Castibility. The relative ease that a molten metal flows through
a casting die. More generally, the relative ease that a casting can
be made with a particular alloy.

Casting. The product that results from the solidification of molten
metal in a mold or die.

Casting Cycle. The total number of events required to make each
casting. For die casting, the cycle generally consists of solidification
time, machine movement, and the operators manual movements.

Cavity. The space within the die casting die that is the size and
shape of the part to be cast. The molten metal flows into this space
and is held until it has solidified.

Cavity Insert. A separate die component inserted into the die block
to form an external feature of the casting. Sometimes the entire
cavity block is referred to as the cavity insert.

Clamping Force. The actual force applied by the die casting
machine to keep the die halves closed. This may be less than the
clamping capacity of the die casting machine.

Cold Chamber Machine. A die casting machine in which the
molten metal pressure chamber is not submerged in the molten
metal to be cast. The metal is ladled into the shot sleeve of the
machine prior to each shot.

Cold Shut. A defect in a die casting that shows as a line on the
casting surface. This is caused when two metal flows meet, but
are to cold to fuse together properly.

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

Core Actuating Mechanism. The various parts of a die casting
die, and their mounting to the die that controls or retains the cores
movement. The mechanism may include cams, slides, detents,
angled pins, and hydraulic cylinders.

Core Pins. A hot work tool steel pin, usually H-13, that is used to
form a cored hole in a die casting.

Density. The unit mass of material, usually expressed in pounds
per cubic inch or kilograms per cubic meter.

Die. A tool used to impact the shape to the casting. Specifically,
two matching steel blocks with their cavities that shape the molten
metal until it solidifies.

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

Die Blow. Describes the dimensional growth of a casting across
the parting line or in the direction of slide movements. A growth
or blow can occur in small amounts without substantial flash

Die, Cover. The half of a die casting die that is attached to the
stationary platen of the die casting machine.

Die, Ejector. The half of a die casting die that contains the ejection
system and that mounts to the moving platen of the die casting

Die, Trim. A die, usually in a power press, that cuts the runners,
overflows, and flash off the die casting.

Die, Unit. A type of die construction that allows quick changing of
the cavity blocks in the holder or die block. This usually can be
performed while the die is still in the machine.

Dimension, Critical. A dimension on a part that must be held
within the specified tolerance for the part to function in its
Draft. A slight angle placed on surfaces that would otherwise be
parallel to the direction in which the die opens. The draft allows
that surface to move away from the cavity wall as the casting is
removed from the die.

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

Ejector. A pin or mechanism that pushes the solidified die casting
out of the die.

Flash. A thin web or fin of metal on a casting which occurs at die
parting, air vents, and around movable cores. This excess metal is
due to the necessary working and operating clearances in a die.

Gate. A thin passage for molten metal which connects the runner
to the die cavity. Also, the entire ejected content of a die, including
the castings, gates, runners, biscuit (or spue), and flash.

H-13 Steel. An air hardening hot work tool steel of fine grain
structure and high cleanliness that is exclusively used for making
die casting dies for casting aluminum, magnesium, and zinc alloys.

Hole, Cored. In a die casting, any hole that is formed by a core in
the die casting die. A cored hole is distinguished from a hole that is
added after the casting has been made (as by drilling).

Hot Chamber Machine. A die casting machine that has the molten
metal pressure chamber immersed in the molten metal in the holing
furnace. The advantage of the hot chamber machine is that the
pressure chamber refills naturally after each shot is made.

Injection. The process of forcing molten metal into die casting

Insert, Cast-In. A piece of material, usually metal, which is placed
in a die and becomes an integral part of the die casting after molten
metal is cast around it.

Magnesium. A low-density silver-white metallic element. Some
alloys of magnesium are widely die cast. Magnesium's specific
gravity is 35.5% less than aluminum.

Metal Saver. A shape made on the cavity of a die casting for the
sole purpose of displacing unnecessary die casting alloy from the
casting. The shape placed on the casting by the metal saver is not
required for the function of the casting.

Overflow. A small reservoir cavity added to the exterior of the die
cavity (on a parting line) to receive impure or cold metal during
cavity fill. Also used to generate added die heat in the local area.

Parting Line. A line-like mark around a die casting where the two
halves of the die came together.

Platen. A large thick flat steel plate that is a major part of a diecasting
machine frame.

Porosity. Any void within a die casting that was not intentionally
created. This includes such voids that are open to the surface of the
casting as well as those that are completely encased within the

Pressure Tightness. A measure of the integrity of a die casting
in terms of its ability to contain a fluid under pressure. The
method of testing and the pressure used must be stated.

Runner. A channel cut into one or both parting faces of a die casting
die to allow the injected molten metal to flow from the sprue or
biscuit to the cavity.

SDCE. The Society of Die Casting Engineers. A society dedicated
to increasing and disseminating the fund of knowledge of die casing,
fostering educational programs, encouraging the investigation of
new techniques, and advancing international development and
growth in die casting and related industries.

Shot. (1) The injection of molten metal into a die casting die. The
metal is injected so quickly that it can be compared to the shooting
of a gun. (2) The solidified metal-consisting of the castings, runners,
overflows, flash, and biscuit (or sprue) - as it is when removed
from a die casting die.

Shot Sleeve. 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.

Shut-Off. In a die casting die, any place where two surfaces are
fitted together with the intent of stopping the flow of any molten
metal between them.

Slide. Any member of a tool, die, or machine that moves in a
straight-line motion and is not parallel to the die pull.

Sprue. (1) The hole in a die casting die (for a hot chamber die
casting machine) through which the molten metal first enters. (2)
The portion of a cast shot formed by the spue hole in the die casting

Statistical Quality Control. A technique for monitoring the quality
of manufactured items, such as die castings, in which only a few
individual items are actually inspected. Estimates as to the general
quality level of the entire lot of items are made from the observed
quality of those inspected.

Tie Bar. The bars (usually round), that connect the stationary platen
to the adjustable platen on a die casting machine.

Trim. To remove the flash, overflows, and runners from a die

Undercut. Any condition in a die casting die cavity that restricts
the ejection of the casting.

Unit. A cavity block for a die casting die that can be installed into
the die block without removing the entire die from the die casting

Unit Die Holder. A particular type of die frame designed to accept
quick interchange unit die sets. A unit holder may remain mounted
in a machine for long service periods, and is complete with an
ejection mechanism, sprue or shot entries, and runner system, but
no cavities.

Vent. A shallow channel cut into the parting face of a die casting
die to let air and other gasses escape from the cavity to the outside
of the die.

Water Line. A passage through a die casting die in which water
flows to cool the die. The correct placement of these channels is a
highly developed science. The degree to which the water lines are
correctly placed is key to productivity in the die casting process.

Zinc. The major constituent of the zinc-base die casting alloys.
This technical information has been contributed by
Hyatt Die Cast & Engineering

Click on Company Name for a Detailed Profile

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