Glossary and Terms of the Foundry Industry

SFSA: Glossary of 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.
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.
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.
dB: See Decibel
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
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.
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.
Dead Steel: Fully killed steel, also applied to steel which fails to respond to heat treatment.
Decant: 1) Pour from one vessel to another, 2) 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 my be developed; i.e., abnormal grain size, segregation, cracks, or grain flow.
Deepbed 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.
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.
Degasser: 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.
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.
Dendrite: A crystal of branched appearance, formed during solidification of alloys, the branching habit being controlled by specific crystallographic directions.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
Die: A metal block used in forming materials by casting, molding, stamping, threading, or extruding.
Die Assembly: The parts of a die stamp or press that hold the die and locate it for the punches.
Die Casting (Brit. Pressure Die Casting): A rapid, water-cooled permanent mold casting process limited to nonferrous metals. There are three types: the plunger-type operated hydraulically, mechanically or by compressed air with or without a gooseneck; the direct-air injection which forces metal from a goose-neck into the die, and the Cold-Chamber Machine. All force the metal into the die with a pressure greater than that of gravity flow.
Die Coating: See Release Agent
Die Insert: A removable liner or part of a die body or punch.
Die Sinking: Forming or machining a depressed pattern in a die.
Dielectric Oven (Dryer): A rapid-drying high frequency electric oven used to bake cores.
Die Set: In stamping, the parts of the press that hold the die and locate it in proper relation to the punches.
Dietert Process: A patented process for the production of precision molds involving blowing a contoured core around a pattern to form half a mold.
Dietert Tester: A patented apparatus for the direct reading of a Brinell hardness after impression without using magnification or conversion tables.
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.
Diffuser: X-ray equipment, a portion of the condensing and focusing system that permits even distribution of energy.
Dike: A patented flexible seal to prevent blow-by in core boxes.
Dilatometer: An instrument for measuring the length of a metal sample during heating and cooling.
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 diecastings are dipped for cooling after leaving the machine.
Dipped Joint: A thin joint made by dipping of the brick in a thin mortar.
Direct-Arc Furnace: An electric arc furnace in which the metal being melted is one of the poles.
Direct Casting: Teeming from the ladle into the casting mold without the use of a tundish.
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.
DIS: See Ductile Iron Society for address
Disappearing Filament Pyrometer (Optical Pyrometer): A telescope in which a hot body is viewed through an eyepiece; 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.
Despersion Hardening: Hardening by the formation of hard microconstituents dispersed in a softer matrix.
See Preciptitation Hardening
Distruptive Strength: Maximum strength of a metal when subjected to three principal tensile stresses at right angles to one another and of equal magnitude.
Dissolved Carbon: Carbon in solution in steel in either the liquid or solid state.
Distorted Pattern: A pattern untrue to the specified dimensions.
Distortion: See Warpage
Distribond: A siliceous clay containing Bentonite used as bond in molding sands.
Distribution, Sand Grain: Variation or uniformity in particle size of a sand aggregate when properly screened by U.S. Standards screens.
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.
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.
Dose: A quantity of radiation measured at a certain point expressed in roentgens, rems or rads.
Dose, Exposure: Quantity of radiation measured in air in roentgens without backscatter at a given point.
Dose Meter, Integrating: Ionization chamber and measuring system designed for determining total radiation administered during an exposure. In medical radiology the chamber is usually designed to be placed on the patient's skin. A device may be included to terminate the exposure when it has reached a desire value.
Dose Rate: Dose per unit time.
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.
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.
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.
Double Skin (bottom Splash, Ingot Shell, Plaster): A defect consisting of a secondary layer of metal sometimes found on top-poured ingots.
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: 1) a wooden or metal pin of various types used in the parting surface of parted patterns and core boxes, 2) in diecasting dies, metal pins to ensure correct registry of cover and ejector halves.
Downcomer: In air pollution control, a pipe for conducting bases down into a conditioner and subsequent cleaning.
Downgate: See Downsprue
Downhand Welding: Welding deposited along a horizontal line and surface.
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, Pattern: See Pattern Draft
Drag: Lower or bottom section of a mold or pattern.
Draw: A term used for 1) to temper, 2) to remove pattern from mold, 3) an external contraction defect on surface of mold.
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.
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.
Drawback: Part of a mold of green sand that may be drawn back to clear overhanging portions of the patterns.
Drawing: Removing pattern from the mold or mold from pattern in production work.
See also Temper
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.
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
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: The property of a molded mass of sand bonded or unbonded, dried at 220-230°F (105-110°C) and cooled to room temperature that allows passage of gases resulting during pouring of molten metal into a mold.
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 to 230°F (105 to 110°C) and cooled to room temperature.
Dryer, Core: See Core Driers
Dryer, Dielectric: See Dielectric Oven
Dual Metal Centrifugal Casting: Centrifugal castings produced by pouring a different metal into the rotating mold after the first metal poured.
Dust: Small solid particles created by the breaking up of larger particles by an process.
Ductile Iron: See Nodular Iron
Ductile Iron Society: See Ductile Iron Society for address

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