Glossary
Abrasive Blasting
The
process by which particle abrasive material is propelled at high velocity, via air
or wheel. This is primarily used for cleaning parts. Little
controls are necessary or used.
Annealing
Annealing applies to softening by changing the
microstructure and is the term used to describe the heating and cooling
cycles in a solid state. Sometimes the terms Stress Relieving is used to
define the heat treatment process used.
Balzers, Phygen, Ion Bond, Melonite, Philo
Popular coatings that may be applied over either
MetaLLife
or
Thermallife substrate where considered necessary
Blast, Sand Blasting Cleaning
Abrasive blast cleaning using sharp edged media for removing debris,
oxides, and other surface contaminants. Will invariably set us stress
risers that lead to shortened tool life and premature failure by fatigue
of the surface
Blistering
See Laminar Fill or Porosity.
Breakout, Die Breakout
Excess
metal protruding from a casting resulting from cracking or pitting of a
molding surface such as a die casting die or plastic injection mold. Is
usually result of unchecked die cavitation effect
Case Hardening
Diffusion and/or heat treatment method that adds high
carbon in a very thin surface layer that increases strength and some
brittleness to OEM parts. Not usually used on tool steels which prefers
a nitriding or carbonitriding hardening method of diffusion
Castings
Object obtained by pouring molten metal in a mold; also
the act of pouring metal. Materials include: aluminum, magnesium, zinc,
gray iron, malleable iron and steel.
Casting Texturing
A
specific texture applied to castings to accomplish a change in cosmetic
finish for appearance or to improve the flow of metal in a die casting
operation in specific areas or the entire die. Often times combined
with compressive stress texturing to provide both flow benefits and
fatigue resistance to thermal cracking.
Cavitation
The
rapid formation and collapse of extremely small violent vapor pockets in
a flowing liquid in regions of pressure changes from very low pressure,
resulting in the pitting of a solid surface; a frequent cause of
structural damage to propellers, pumps, die casting dies, etc.
Cavity
(in reference to die casting or plastic injection molding)
A
hollow space within one or multiple sets of die castings dies or plastic
injection molds where molten metal or plastic will flow into to make
castings or parts. Cavity can be reference to an insert or set of
inserts inserted into a holder block or mold base.
Coating processing, Coatings
PVD (lower temperature) Physical Vapor
Deposition treatments that when applied to proper substrates of ferritic
nitro carburizing provide added benefits of improved performance and
sometimes extended life. CVD (high temperature) Chemical Vapor
Depositions are specifically limited since their application temperature
requires that tooling, especially die casting tools, needs to be
completely again heat treated. Colorado School of Mines is the present
authority on research being done to evaluate a smart coating that when
applied can prevent soldering in die casting dies.
Compressive Stress, Compressive Stress Texturing
An
internal beneficial resistance set up by a material (Tool Steel) when it is
deformed. Measured in units of force per unit area (MPa) or KSI
(kilograms/sq in) with a -y axis value to indicate compression.
Compressive stress (beneficial) and Tensile stress (detrimental) work in
opposition to one another. The
Core
A
specially formed refractory object inserted into a mold or die to
produce cavities or depressions in the casting that cannot be readily
formed on the pattern.
Cover Insert
CVD
Coatings
This
high temperature coating process, as it relates to tooling applications,
involves the deposition of a solid material onto a heated substrate via
a chemical reaction from a gas phase. This process can be done in
atmosphere or vacuum. Because this is a chemical bond, the bond
strength is many times stronger than achieved through the PVD process.
CVD is typically used for carbide inserts, forming tools and other high
load applications. Due to the high processing temperature (1925° F),
there are some material and tolerance limitations. Due to the high
processing temperature, all tool steels and High Speed Steels (HSS) must
be heat treated after this coating process.
Decarburization
Loss
of carbon from the surface layer of a carbon-containing alloy due to
reaction with one or more chemical substances in a medium that contacts
the surface.
Diamond
Polishing
The
act of polishing a tool steel’s surface to a mirror finish. Using
special polishing compounds, the surface is completely smooth and
contains no surface inclusions. The act of applying a mirror finish
also induces small levels of compressive stress
which increases the fatigue strength of the tool steel. Because of cost
is usually performed only in critical and most likely failure areas such
as fillets and radii. Any surface inclusions such as scratching or
polishing marks create little stress risers
where cracks can propagate from leading to die cracking failure. To be
most effective usually done to a previously prepared compressive stress
surface to substantially increase the compressive stress benefits and
value.
Discontinuity
An interruption in the normal physical structure or
configuration of an object, such as cracks, forging laps, seams,
inclusions and porosity.
Dwell
Time
(In reference to Peening)
The total time that the media is in contact with a
specified area or the test or production part surface. Dwell time is
not to be confused with saturation of the peened surface which pertains
more to coverage percentage.
EDM
(Electrode Discharge Machining)
A manufacturing process whereby a wanted shape of an
object, called a work piece, is obtained using electrical discharges
(sparks). The material removal from the work piece occurs by a series of
rapidly recurring current discharges between two
electrodes,
separated by a
dielectric
liquid
and subject to an electric
voltage.
Ejector
Insert
Part
of a die casting die or plastic injection mold that contains holes where
ejector pins travel
through to eject plastic or alloyed parts from the die or mold.
Ejector
Pin
Pins
that protrude from an ejector insert
which eject plastic or alloyed parts from the die or mold.
Equo-Tip
Tester
A professional, portable device used to test hardness of
pieces ranging from massive steel rolls, heavy forgings, castings, die
steels, to bar stock, pipes and cylinders, and more.
Ferritic
Nitro Carburizing
(FNC)
Any of
several processes in which both nitrogen and carbon are absorbed into
the surface layers of a ferrous material at temperatures below the lower
critical temperature and, by diffusion, create a concentration
gradient. Nitro carburizing is done mainly to provide an anti-scuffing
surface layer and to improve fatigue resistance.
Finishing
The process used to refine or roughen a surface to meet
surface finish requirements, or to clean, strengthen or prepare the
surface for additional processing.
Flash
Excess material on molded component resulting from a
leakage at joining surfaces in a casting process.
Ferrous
Metals
Alloys containing iron.
Forging
A
process where metal is shaped by pressing, pounding, or squeezing under
very high pressure, to form forgings.
Gross
Cracking
A mode of die failure in the die casting industry
Heat
Treatment
An operation or combination of operations involving
heating and cooling of metal or an alloy in a solid state for the
purpose of obtaining certain desirable conditions or properties.
Heat
Checking
Also known as fatigue fracturing, this type of tool
damage generally occurs when repeated or fluctuating stresses have a
maximum value less than the tensile strength of the substrate:
basically, the tool has been overloaded. This type of fracture is
generally progressive, beginning as minute cracks that grow under the
action of the fluctuating stress. This is a common tool failure mode
for die casting dies and hot work steels.
Holder
Block
An
apparatus used by die casters meant to contain inserts that are used to
create parts or castings. The holder block also contains cooling lines
and connections used to dissipate heat from the die casting or molding
process.
Insert
One
part of a die casting die or plastic injection mold, containing an
impression and cooling lines, that will ‘inserted’ into a
holder block or
mold base and will subsequently create a part
or casting.
Laminar
Fill
In die
casting, where a thin skin of cooled aluminum at the surface of a
casting traps gases, bubbles, or pores just below the surface resulting
in a blister on the
final part.
Lubricity
The
ability to lubricate; capacity for lubrication.
Mold
A term
used in the plastic injection industry for a hollow form or matrix for
giving a particular shape to something in a molten or plastic state.
NADCA
(North American Die Casting Association)
An
organization headquartered in Wheeling, IL designed to promote die
casting industry awareness
Nitriding
A
process of case hardening in which nitrogen is introduced to the surface
layer of a solid ferrous alloy by holding at a suitable temperature in
contact with a nitrogenous material, usually ammonia of appropriate
composition.
Pitting
A
hollow or depression in a die casting die or molding die surface
resulting in a mirrored riser on a casting or part. The pitting usually
results from a phenomena called cavitation effect.
PVD
Coating
Physical Vapor Deposition, or PVD, is a term used to describe a family
of relatively low temperature (750° F) vacuum coating processes that
involve the generation of positively charged ions through various
methods. Reactive gases are introduced into the chamber to create
various compounds. The positively charges ions are attracted to a
negative bias given to the tool substrates. This attraction results in
a dense thin-film layer with an extremely strong physical bond to the
tool substrate.
Porosity - Casting Porosity
In die
casting, a part containing pores created by trapped gases,
cavitation bubbles, or other
mechanical means of bubble creation related to flow or tool geometry.
Quenching
The
rapid cooling of tool steel to obtain desirable tool characteristics by
developing proper microstructure and steel properties. For die
casting tools, it is recommended that the rate of cooling be at least 50
degrees F/min which is usually obtained by using liquid nitrogen
introduction into a vacuum chamber device. Higher cooling rates
are possible using oil as the quenching material, however, care must be
taken to evaluate the size of the piece of steel being quenched. A
high quench rate can result in a gross quench cracking of material for
larger insert tooling.
Residual
Stress
A
stress in a metal, on a microscopic scale and resulting from non-uniform
thermal changes, plastic deformation, or other causes aside from
temporary external forces or applications of heat. There are two types
- Tensile residual stress which is also commonly called detrimental
residual stress since it causes metal to fail by pulling on the core
structure....Compressive residual stress or controlled compressive
stress which can be induced to create and thus prevent premature fatigue
in all types of steel. Used extensively in the die casting industry for
controlling residual stress build up from cycle failure in die casting
dies, slides, and sometimes larger core pins.
Rockwell
Hardness
A measurement system used by commercial manufacturers to
determine the relative hardness of objects based on the depth of
indentation from a heavy object.
Shot
Blasting
The cleaning process using loose abrasive is propelled at
high velocity, and aimed at an area to be cleaned. This process is
typically used to remove flash, rust, scale, old paint, or any other dry
surface contaminants.
Shot
Peening
The procedure of impacting a metal surface with a
high-velocity stream of metal shot or glass beads for the purpose of
improving resistance to fatigue by induction of compressive stress.
Sodium
Hydroxide
(NaOH)
In die casting, a strong basic chemical used to dissolve
aluminum solder without attacking the base tool steel.
Soldering
In die casting, the loss
of a tool’s protective surface or lubrication barrier between the die
and cast molten metal which allows the
creation of
inter-metallic compounds
that cause a chemical adhesion of the cast metal to the die's
surface.
Stress
Relieving
The heat treatment
process used to anneal the steel. For die casting dies, this is
the temperature above the final temper which is usually at or above 1100
degrees F..
Stress
Riser
The most likely
location where a cracking failure is likely to occur. This is
usually in tight radius/radii and sharp corners.
Stress
Temper
The heat treatment
process used to normalize steel (remove tensile stress build up).
This is done at a temperature that is lower than the final hardening
temper temperature. For die casting tooling, the stress temper
temperature is something less than 1100 degrees F. The duration is
calculated at 1 hour per inch of maximum thickness.
It is
commonly used to relieve or dissipate
stresses in weldments, heavily machined parts, castings and forgings.
The parts are heated to a suitable temperature, holding long enough to
reduce residual stresses, and are then slowly cooled enough to minimize
the development of new residual stresses.
Tensile
Stress
A type of stress in which the two sections of material on
either side of a stress plane tend to pull apart or elongate.
Large tensile stress conditions may lead to failure of the material.
Values are given to steel to show how much force is necessary for this
to occur.
Measured in units of force per unit area (MPa) or KSI
(kilograms/sq in) with a +y axis value to indicate tensile.
Ultrasonic
Cleaning -
Solder removal
Acoustically created cavitation bubbles in a proprietary
chemical solution where a die cast die, plastic injection mold, or
rubber mold is placed for cleaning. The imploding cavitation bubbles act as a
mechanical means of removing foreign material, where as the proprietary
chemical solution (usually consisting of sodium hydroxide (NaOH) along
with other buffers and detergents) chemically remove foreign material.
Any residual cast material, such as aluminum solder, along with grease
or oil is removed from the casting surface, water/oil lines, etc. The
base tool steel is completely unaffected by the cleaning process.
Welding, Die cast die welding stress relieving
Used to make changes to the die metal
during PPAP (die casting configuration finalization before production)
or to repair larger cracks or cavitation metal breakout that would not
allow acceptable castings. The weld should be followed by a 1000 degree
F stress temper to normalize the steel and remove the high tensile stresses
that build up during the welding procedure. To be most effective this
is then followed by a compressive stress peening process to add
additional fatigue strength along with being able to check the integrity
of the welded area.
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