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Glossary of Foundry Terms - N

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Nail, Chill

Steel nail with a heavy head which is inserted in the mold wall to hasten cooling of the metal at that point.

Natural Aging

See Aging.

Natural Sand

Unconsolidated sand, sand derived from a rock in which grains separate along their natural boundaries. This includes soft sandstone where little pressure is required to separate the individual grains. See Molding Sand, Naturally Bonded Molding Sand.

Naturally Bonded Molding Sand

A sand containing sufficient bonding material as mined to be suitable for molding purposes. Seldom used today in the metalcasing industry. See Molding Sand.

Navy (USA) Tear Test

A method of evaluating the susceptibility of ship plate to brittle or cleavage type fracture.

Neat Brick

Brick with faces arranged so one of the flat faces in inclined toward the other, almost eliminating one end face.

Neat Cement

Portland Cement mixed with water only.

Neck Down (Knock-Off, Wafer Core, Washburn, Cameron Core)

A thin core or tile used to restrict the riser neck, making it easier to break or cut off the riser from the casting. See Core.

Necking

Reducing the cross sectional area of the metal in an area by stretching.

Necking Down

Reduction in area concentrated at the subsequent location of fracture when a ductile metal is stressed beyond it yield point in tension.

Needles

Elongated acicular crystals, tapering at each end to a fine point, as martensite.

Needling Agents

Special agents such a boron which markedly increase the hardness of steel.

Negative Quenching (Negative Hardening)

Accelerated cooling in water or oil, from a temperature below the critical range. See Quenching.

Negative Thermoie Heat Exchange

In shell molding, improving the mass-surface ratio by simulating profile geometry of pattern or core cavity on the underside; will boost running temperature of high projections by 25%. See Shell Molding.

Nesh (Hot Short)

A British term applied to metal that is weak and ruptures easily under not working conditions.

Network Structure

A structure in which the grains or crystals of one constituent are partly or entirely enveloped in another constituent; an etched section through the crystals resembles a network.

Neumann Band

A mechanical twin in ferrite.

Neutral Refractories

A loose term designating refractories which presumably will not react with so-call acid or basic refractories and slags. See Refractory, Slag.

Neutron

Elementary nuclear particle with a mass (1.00893 mass units) approximately the same as that of a hydrogen atom. It is electrically neutral.

New Jersey Sand

A large number of grades of foundry sands mined in southern New Jersey.

Nichrome

Oxidation-resistant alloy 65% Ni, 20% Fe, and 15% Cr.

Nickel

An element used for alloying iron and steel as well as nonferrous metals; melting point 1455°C (2651°F). Nickel is also a base metal for many casting alloys resistant to corrosion and high temperature oxidation. Nickel’s chemical symbol is Ni. Its formula weight is 58.69, the specific gravity is 8.90, and nickel’s melting point 1,452°C. See Monel, Nimonic, Inconel, Ni-Hard.

Ni-Hard

Hard white cast iron containing 4% Ni and 2% Cr. See White Cast Iron.

Nil Ductility Transition Temperature (NDDT)

Determined in the dropweight test. Refers to the absence of the ductile fracture appearance and any reduction in area due to the brittle behavior of the steel. See Ductility.

Nimonic

Class of nickel-base cast alloy resistant to stress and to oxidation at high temperatures. See Inconel.

Nine-Inch Equivalent

Standard unit of volume in refractories industries; 9 x 4-1/2, 2-1/2 in brick.

Nipple

A pipe coupling consisting of a short piece of threaded tubing.

Nital

A solution of nitric acid in alcohol use as an etching agent in ferrous metallography.

Nitriding

A surface hardening process involving heating in a atmosphere of ammonia or in contact with a nitrogen-bearing material so as to promote the absorption of nitrogen.

Nitrogen Flush

Bubbling nitrogen gas through a metal melt under vacuum (as with valve bronze) to improve tensile properties and pressure tightness.

Nobake Binder

A synthetic liquid resin sand binder that hardens completely at room temperature, generally not requiring baking, used in the Cold Setting process. See Cold Setting Process.

No-Bake Process

Molds/cores produced with a resin bonded air setting sand. Also known as the air set process because molds are left to harden under normal atmospheric conditions. See Core, Mold.

Noble Metals

Metallic elements with surfaces that do not readily oxidize in air; e.g., gold, silver, platinum.

Nodular Fireclay (Burley, Burley Flint)

Rock containing aluminous or ferrogenous nodules, or both, bonded by fireclay.

Nodular Graphite

Graphite or carbon in the form of spheroids, characteristically in malleable and nodular iron.

Nodular Iron

Cast iron, normally gray cast iron, which has the major part of its graphitic carbon in nodular from. See Ductile Iron.

Noise Radiator

A device creating noise.

Noise Spectrum

The various frequencies making a noise.

Nomogram (Graph)

A graph that enables one by the aid of a straight-edge to read off the value of a dependent variable when the value of two or more independent variables are given.

Nondestructive Testing (Inspection)

Testing or inspection that does not destroy the object being tested or inspected.

Nonferrous

A negative term, refers to alloy in which the predominate metal or solvent is not iron. See Alloy.

Nonferrous Metal Casting

Metal casting done with a nonferrous metal, in which the molten metal is poured into a mold, cooled, and allowed to solidify. See Nonferrous.

Nonferrous Metal Processing

The processing of a nonferrous metal, such as by melting, alloying, or casting. See Nonferrous.

Normal Segregation

Concentration of alloying constituents that have low melting points in those portions of a casting that solidify last.

Normal Steel

Steel in which the pearlite is completely laminated. See Pearlite.

Normalizing

Heating a ferrous alloy to a suitable temperature above the transformation temperature Ac3, followed by cooling at a suitable rate, usually in still air to a temperature substantially below the transformation range.

Notch Bar

Small size ingot with notches to facilitate breakage for remelting.

Notched Bar

A test specimen which is notched. Used in impact or fatigue tests.

Novalak

A two-step basic flake resin with no thermosetting properties, applied to sand in shell molding process as a mold or solution. See Shell Molding.

Nowel

The lower section of the flask, commonly called the drag. See Drag, Flask.

Nozzle

Pouring spout of the bottom-pour ladle. See Ladle.

Nozzle Brick

A thick-walled tubular refractory shape set in bottom of a ladle through which steel is teemed.

Nozzle Pocket Brick

A refractory shape set in bottom of a ladle containing a recess in which nozzle is set. See Ladle.

NTP

Abbreviation for normal temperature and pressure reference point, zero centigrade 760 mm mercury pressure.

Nucleus

The first structurally determinate particle of anew phase or structure that may be about to form. Applicable in particular to solidification, recrystallization, and transformations in the solid state.

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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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