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Home > Glossary of Foundry Terms > D

Glossary of Foundry Terms - D

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D (Fordath) Process

Shell molding in which the shell is made by blowing sand into a box like heated structure so that a shell of controlled thickness is created. See Shell Molding.

Damping Capacity

The ability to absorb vibration. More accurately defined as the amount of work dissipated into heat by a unit volume of material during a completely reverse cycle of unit stress.

Datum Plane

In layout and machining operations the reference plane from which dimensions are measured in the perpendicular direction.

Datum Points

In layout and machining operations the reference points on a datum plane from which dimensions are measured.

Daub

To coat or plaster the inside of a cupola at the melting zone or the inside of a ladle with a refractory mixture.

Daubing

Filling of cracks in molds or cores by specially prepared pastes or coatings to prevent a mechanical penetration of metal into these cracks during pouring. Also, the final plastering or coating of the cupola or ladle after shrinkage has taken place during the drying period. Clay slurry or clay wash with various coating compounds are applied. See Clay Wash.

DC (Direct Chill) Casting

A continuous method of making ingots or billets or extrusion by pouring the metal into a short mold. Some times called semi-continuous casting.

Dead Annealing

See Annealing.

Dead Steel

Fully killed steel, also applied to steel which fails to respond to heat treatment. See Heat Treatment, Killed Steel.

Deadburned

Term applied to refractory materials obtained by calcimining at a temperature high enough to form a product inert to atmospheric moisture and carbon dioxide, and less apt to contract. See Refractory.

Deadburned Dolonite

Dolonite burned at high temperature with additions of an agent, such as oxide of iron.

Deadhead

The useless metal projecting on a casting which corresponds to the position of a riser in the mold. See Casting, Riser.

Decant

Pour from one vessel to another. Pour off molten metal without disturbing the sludge.

Decarburiztion

Loss of carbon from the surface of a ferrous alloy as a result of heating in a medium, usually oxygen, that react with carbon.

Decibel (dB)

Unit for measuring the ration amounts of acoustical power; one-tenth of a bel.

Deep Etching

Macroetching; etching for examination at a low (less that 10X) magnification, in a reagent that attacks the metal to a much greater extent than normal for microscopic examination. Gross features may be developed; i.e., abnormal grain size, segregation, cracks, or grain flow.

Deep Red Filter

A gas filter in air pollution control, consisting of a loosely packed mat of fibrous materials; not practical where high grain loading are encountered.

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Defect

A discontinuity in the product whose severity is judged unacceptable in accordance with the applicable product specification.

Deformation test

An AGS test using an instrument such as the Dietert Universal Sand-Strength Testing machine (with deformation accessory) to determine the amount in inches that the sand specimen is compressed before it ruptures.

Degasifier

A material employed for removing gases from molten metals and alloys.

Degassing

Usually a chemical reaction resulting from a compound added to molten metal to remove gases from the metal. Often inert gases are used in this operation.

Degassing Flux

A flux for removing gas from the melt.

Degree of Ramming

The extent of hardness to which a sand mold is rammed. See Ramming, Sand Molding.

Delay Screen (Skim gate (Erroneously), Skim Strainer)

A small piece of perforated light gage tinned sheet steel, or of copper, aluminum, and/or magnesium alloys, frequently placed in the pouring basin at the top of the downsprue. It delays the flow of metal long enough to allow the basin to fill before it melts to permit only clean metal from the bottom of the basin to enter the downsprue. Delay screens are also use elsewhere in the gating system.

Delta Iron

An allotropic (polymorphic) form of iron, stable above 2550°F, crystallizing in the body-centered-cubic lattice.

Dendrite

A crystal of branched appearance, formed during solidification of alloys, the branching habit being controlled by specific crystallographic directions with the branching structure resembling a a fir tree.

Densitometer

Instrument utilizing the photoelectric principle to determine the degree of darkening of developed photographic film.

Density

The mass per unit volume of a substance, usually expressed in grams per cubic centimeter or in pounds per cubic foot.

Density (Photographic)

Density is used to denote the degree of darkening of photographic film. Logarithm of opacity of exposed and processed film. Opacity is the reciprocal of transmission; transmission is the ratio of transmitted to incident intensity.

Dephosphorization

Elimination of phosphorus from molten steel.

Dermatis

An inflammation of the skin, which may be caused by allergy to certain casting adjuncts, as resins; particularly in the shell process.

Descale

Remove the fire scale from the surface of casting. See Casting.

Design Base Line

The noise spectrum which is the goal of any particular noise reduction program.

Designations

Type of metal named, as steel, malleable, nonferrous, etc.

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Despersion Hardening

Hardening by the formation of hard microconstituents dispersed in a softer matrix. See Precipitation Hardening.

Desulfurization

Removal of sulfur from the molten metal by addition of suitable compounds.

Desulfurizer

A material used to remove sulfur from molten metals and alloys. Also, a form of holding ladle or basin in which the molten metal and desulfurizing material are brought into contact. See Ladle.

Detroit Cup Test

A cupping test for sand, using a steel ball as plunger, the depth of cup being shown on a dial.

DeVries Test

A test to give the relative hardness of deep hardening steels. See BHN, Brinell Hardness.

Dew Point

The temperature at which moist air will become saturated and condensation of water vapor will take place.

Dewaxing

The process of melting out the expendable was pattern from an investment mold by the application of heat, usually at temperatures less than 250°F (121°C).

Dexidation

Removal of excess oxygen from molten metal, usually accomplished by adding materials with a high affinity for oxygen, the oxides of which are either gaseous or readily form slags.

Dextrin

Soluble gummy carbohydrate formed by the decomposition of starch by heat, acids, or enzymes; it is use din core compounds, mold compounds, mold washes, core pastes, and other compounds requiring high dry compressive strengths.

Dezincification

Corrosion of some copper-zinc alloys, involving loss of zinc and the formation of a spongy porous copper. See Alloy.

Diameters

In microscopy, an indication of the amount of magnification. 1000 diameters = 1000 times original size.

Diammonium Phosphate

Used to fireproof clothing of foundry workers.

Diaphragm Shell Molding Machine

An arrangement for applying a squeeze pressure with a high-temperature silicone rubber diaphragm.

Diaspore Clay

A rocklike mineral consisting chiefly of diaspore (HAlO2) bonded by fire clay substance with an alumina content higher than 63%.

Dia-Tester (Wolpert Hardness Tester)

A hardness testing machine using the Vickers or Brinell ball indenter. See BHN, Brinell Hardness, Vickers Diamond.

Diathermometer

An instrument for examining the thermal resistance or the heat conducting power of objects.

Diatomaceous Earth (Infusorial Earth)

A hydrous of silica which is soft, light in weight and consists mainly of microscopic shells of diatoms or other marine organisms.

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Die

A metal block used in forming materials by casting, molding, stamping, threading, or extruding. A metal form used as a permanent mold for die casting or lost wax process. See Lost Wax Process.

Die Assembly

The parts of a die stamp or press that hold the die and locate it for the punches.

Die Casting

(a) Forcing molten metal into permanent molds, dies. Die Casting is also called Pressure Casting. See Pressure Die Casting. (b) noun Casting resulting from die-casting process. (c) verb Pouring molten metal under pressure into metal molds.

Die Casting, Cold Chamber

Type of casting made in a die-casting machine in which the metal injection mechanism is not submerged in the molten metal.

Die Casting, Hot Chamber

Type of casting made in a die-casting machine in which the metal injection mechanism is submerged in the molten metal.

Die Coating

See Release Agent.

Die Insert

A removable liner or part of a die body or punch.

Die Set

In stamping, the parts of the press that hold the die and locate it in proper relation to the punches.

Die Sinking

Forming or machining a depressed pattern in a die.

Dielectric Baking

Baking of cores and molds in a field of high-frequency electric current generated by dielectric equipment; employed with resin-bonded cores. See Bake, Baked Core.

Dielectric Oven (Dryer)

A rapid-drying high frequency electric oven used to bake cores. See Bake, Baked Core.

Dietert Process

A patented process for the production of precision molds involving blowing a contoured core around a pattern to form half a mold. See Core, Mold, Pattern.

Dietert Tester

A patented apparatus for the direct reading of a Brinell hardness after impression without using magnification or conversion tables. See BHN, Brinell Hardness.

Differential Heat Treatment

A heating process by which the temperature is varied within the object so that, after cooling, various parts may have different properties as desired. See Heat Treatment.

Diffuser

X-ray equipment, a portion of the condensing and focusing system that permits even distribution of energy. See X-Ray.

Diffusion

Movements of atoms within a solution. Net movement is usually from regions of high concentration to regions of low concentration to achieve homogeneity of the solution which may be a solid, gas, or liquid.

Dike

A patented flexible seal to prevent blow-by in core boxes. See Core Box.

Dilatometer

Instrument for measuring expansion or contraction, the length of a metal sample, caused by changes in temperature or structure.

Dimensional Stability

Ability of a casting to remain unchanged in size and shape under ordinary atmospheric conditions.

Dimensional Tolerance Grades

A system of classifying the tightness of tolerances for the purpose of defining accurately the tolerances involved, and for simplifying the communication process between customer and producer regarding what is wanted, and what is possible, respectively.

Dip Coat

In solid and shell mold investment casting, a fine ceramic coating applied as a slurry to the pattern to produce maximum surface smoothness, followed by a cheaper conventional investment. See Investment Precoat.

Dip Tank

A tank, preferably lined with rubber, epoxy, or other nonmetallic, into which die castings are dipped for cooling after leaving the machine.

Dipped Joint

A thin joint made by dipping of the brick in a thin mortar.

Direct Casting

Teeming from the ladle into the casting mold without the use of a tundish.

Direct-Arc Furnace

Electric furnace in which the material is heated directly by an arc established between the electrodes and the work. See Dielectric Furnace.

Directional Solidification

Refers to the arrangement of a solidification pattern in a casting by establishment of high temperature gradients, whereby solidification of the metal begins at the point farthest from the metal entrance or sprue and the metal progressively freezes or solidifies to and including the sprue. See Solidification.

Dirt

Indefinite term referring to any extraneous material entering a mold cavity and usually forming a blemish on the casting surface. See Mold Cavity.

Dirt Trap

A well employed in a gating system to entrap the first metal poured, which may contain dirt or unwanted particles (ineffective). See Slag Trap.

Dirty Casting

A casting containing an excessive amount of nonmetallic inclusions in the body of the metal. See Inclusion.

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Disamatic Molding

Disamatic molding is a type of sand molding process in which molten metal is poured into a mold made of sand to make Gray Iron Castings. Disamatic machines are designed to provide molds built for vertical casting and the molds are created in a vertical orientation. Disamatic machines create flaskless molds. Disamatic molding gets its name from the company that manufactures the molding machine, DISA. A Disamatic molding machine is a vertically parted sand molding machine. The vertical molding machine is often the choice for production of very close tolerance Gray Iron Castings. See Gray Iron, Hunter Molding.

Disappearing Filament Pyrometer (Optical Pyrometer)

A telescope in which a hot body is viewed through an eyepiece and temperature is measured by the matching color of a calibrated lamp filament with color of hot metal.

Dispersed Shrinkage

Small shrinkage cavities dispersed through the casting, which are not necessarily cause for rejection. See Casting, Cavity, Shrinkage.

Dissolved Carbon

Carbon in solution in steel in either the liquid or solid state.

Distorted Pattern

A pattern untrue to the specified dimensions. See Pattern.

Distortion

See Warpage.

Distribond

A siliceous clay containing Bentonite used as bond in molding sands. See Molding Sands.

Distribution, Sand Grain

Variation or uniformity in particle size of a sand aggregate when properly screened by U.S. Standards screens.

Distruptive Strength

Maximum strength of a metal when subjected to three principal tensile stresses at right angles to one another and of equal magnitude.

Disturbed Metal

The cold worked metal formed on a polished surface during the processes of grinding and polishing.

Divorced Pearlite (Granular perlite, Spheroidite, Spheroidized cementite)

Pearlite in which the cementite has been spheroidized by prolonged annealing just below the Ac1 point, or by annealing at the same temperature after cold working. See Ac1, Pearlite.

Dolomite

A mineral calcium-magnesium carbonate (Ca, MG (CO3)2) used as a flux in iron melting and smelting; also as a base in refractors.

Dosimeter

Instrument used to detect and measure an accumulated dosage of radiation; in common usage it is a pencil-size ionization chamber with a built-in self-reading electrometer; used for personal monitoring. See Dosimeter, Pocket.

Dosimeter, Pocket

A pocket ionization chamber containing it own electrometer. An auxiliary charging device is usually necessary. See Dosimeter.

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Double Annealing

As applied to hypoeutectoid steel, a process of heating to above the upper critical point, Ac3, and holding at that temperature until complete solution of the carbide has been achieved then cooling rapidly and reheating immediately to above A3 and slowly cooling. See Ac3, Annealing.

Double Impression Method

A way of determining approximate Brinell hardness by placing a hardened steel ball between a specimen of known hardness and the metal to be tested and pressurizing in an arbor press. See BHN, Brinell Hardness.

Double Skin (Bottom Splash, Ingot Shell, Plaster)

A defect consisting of a secondary layer of metal sometimes found on top-poured ingots. See Ingot.

Double Tempering

A retempering operation sometimes necessary for steel containing retained austenite which breaks down during cooling from the first tempering to form a new and hence untempered martensite.

Doublebruned

Deadburn; not be mistaken for two firing.

Dowel

A pin used between the sections of parted patterns or core boxes to locate and hold them in position, registering them correctly. See Core Box.

Downcomer

In air pollution control, a pipe for conducting bases down into a conditioner and subsequent cleaning.

Downgate

See Downsprue.

Downsprue (Sprue, Downgate)

The first channel, usually vertical, which the molten metal enters; so called because it conducts metal down into the mold.

Downtime

Time lost from normal casting activity, due to unscheduled interruptions.

Draft

The taper on vertical surfaces of a pattern which allows easy withdrawal of the pattern from a compacted sand mixture without distorting or tearing of the sand and without excessive rapping and tearing of the mold walls.

Draft, Pattern

See Pattern Draft.

Drag

Lower or bottom section of a mold, pattern or flask. See Mold, Pattern, Flask.

Draw

A term used to temper, to remove pattern from mold, as an external contraction defect on surface of mold.

Draw (verb)

To remove a pattern from a mold.

Draw Bar (noun)

A bar used for lifting the pattern from the mold. See Mold, Pattern.

Draw Peg

A wooden peg used for drawing patterns.

Draw Plate

A plate attached to a pattern to facilitate drawing of a pattern from the mold.

Draw Screw

A threaded rod with an eye screwed into a pattern to enable it to be drawn from the mold. See Mold, Pattern.

Draw Spike

A steel spike used to rap and draw a pattern from the sand; it is driven into the wood of the pattern, as opposed to a Draw Screw, which threaded.

Draw, Surface

Appearance of shrink on the upper surface of a casting. See Casting, Shrink.

Drawback

A part of the mold, made of green sand, which may be drawn back to clear overhanging portions of the pattern. It is rammed up on a plate or arbor so that it can be lifted away. See Arbor, Mold, Pattern, Ramming.

Drawing

Removing pattern from the mold or mold from pattern in production work. See Temper.

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Dried Sand

Sand which bas been dried by mechanical dryer prior to use in core making.

Drier (Dryer)

A material, as alcohol ammonium nitrate, sodium perborate and manganese oleate, added to a core or mold mixture to remove or reduce the water content.

Drier-Core

Plates for supporting odd shaped cores during baking.

Drillings, Test

Chips, or small particles of metal removed from a test specimen for chemical analysis.

Drop (Dropout)

A casting defect caused by sand dropping from the cope or other overhanging section.

Drop Ball

A heavy weight, usually ball or pear shaped, dropped from a height to break large pieces of metal scrap. Also used to strengthen warp castings.

Drop Gate

A term for a pouring gate or runner leading directly into the top of the mold.

Drop Off or Drop Out

Sand falling from the Cope of a mold. See Drop.

Drop or Drop Out

The falling away of a body of sand when the mold is jarred or lifted.

Dropping the Bottom

Removal of the supporting props under the cupola bottom doors to permit emptying of the remaining contents. See Cupola.

Dross

Metal oxides and other scum on the surface of molten metal or in a metal or alloy (mostly a non-ferrous term).

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Drum Ladle

A cylindrical refractory-lined ladle that is completely enclosed. A removable cover at the pouring spout permits addition of molten metal.

Drum, Magnetic

An electrically energized pulley or drum used for removing magnetic materials from sand, nonferrous borings and turnings, etc.

Dry Analysis

A term applied to spectrographic analysis.

Dry And Baked Compression Test

An AFS test to determine the maximum compressive stress that a baked sand mixture is capable of developing.

Dry Pan

A grinding machine of heavy rollers or millers testing on a bed. Screens or slits allow fine material to pass through.

Dry Permeability

Property of a molded mass of sand dried at 221°F to 230°F and cooled to room temperature, to permit passage of gases through it.

Dry Sand

Sand mixture that is baked to produce strong molds that are moisture free.

Dry Sand Casting

The process in which the sand molds are dried at above 212°F (100°C) before using.

Dry Sand Core

See Core.

Dry Sand Mold

A mold from which the moisture has been removed by heating.

Dry Strength, or Dry Bond Strength

The maximum compressive, shear, tensile, or transverse strength of a sand mixture which has been dried at 220°F to 230°F (105°C to 110°C) and cooled to room temperature.

Dryer, Core

See Core Driers.

Dryer, Dielectric

See Dielectric Oven.

Dry-Sand Mold

A mold made of prepared molding sand dried thoroughly before being filled with metal. See Mold, Molding Sand.

Dual Metal Centrifugal Casting

Centrifugal castings produced by pouring a different metal into the rotating mold after the first metal poured.

Ductile Iron

A type of iron in which the graphite content takes spherical rather than flake form. Ductile iron is produced by adding magnesium. The spherical form of the graphite provides greater tensile strengths and flexibility than other types of iron. An iron/graphite composite in which the graphite exists in spheres or nodules, allowing the material to deform rather than fracture when placed under mechanical stress. Also called Nodular Iron. Iron in which carbon is in the form of spherical nodules. See Nodular Iron.

Ductility

The property permitting permanent deformation by stress in tension with out rupture.

Duplexing

Term usually used in reference to melting metals or alloys in one type of furnace and transferring to another for holding, refining, etc. Common in the malleable field, where charges are melted in a cupola and transferred to air or electric furnaces for slight reduction of carbon and an increase in temperature.

Dust

Small solid particles created by the breaking up of larger particles by a process.

Dye Penetrant

Penetrant is used to crack detection, which has a dye added to make it more readily visible under normal or black-lighting conditions. In the case of normal lighting, the dye is usually red and nonfluorescent. With black lighting, the dye is fluorescent and yellow-green in color.

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Atlas Foundry Company, Inc.
601 N. Henderson Avenue
Marion, IN 46952-3348
Telephone: (765) 662-2525 • Fax: (765) 662-2902
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