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Home > Glossary of Foundry Terms > R

Glossary of Foundry Terms - R

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Radiant Heat

Heat communicated by radiation and transmitted by electromagnetic waves.

Radiation Area

Any part of an installation accessible to employees in which there exists a radiation level of 7.5 millirem in any one hour over 150 millirem in any seven consecutive days.

Radiation Hazard

Any situation where persons might be exposed to radiation in excess of the maximum permissible dose.

Radiation, Direct

All radiation coming from within an x-ray tube and tube housing except the useful beam.

Radioactive Isotope

Varieties of an element possessing the same chemical characteristics but emitting detectable radiation's by means of which they can be identified and traced.

Radioactive Material

Any compound or element which may emit any or all of the following: alpha and beta particles, electrons, photons neutrons and gamma and all other emissions which produce ionization directly or indirectly.

Radiographic Inspection

Examination of the soundness of a casting by study of radiographs taken in various areas or of the whole casting.

Radiographic Testing

Use of x-or gamma rays in studying the internal structure of objects to determine their homogeneity.


A radioactive element which the chemical symbol Ra; radium and its salts are used in gamma-ray radiography because of their radioactivity. Radium's melting point is 700°C (1,292°F).


Process of packing sand in a mold using a hand, pneumatic or mechanized ramming device.


Tool for ramming the sand. See Ramming.


Packing sand in a mold by raising and dropping the sand, pattern, flask on a table. Jolt squeezers, jarring machines, and jolt rammers are machines using this principle.

Ramming Up

The process of packing the sand in the mold or core box with a rod or rammer.

Ram-Up Core

See Core, Ram-Up.


The difference between the highest and lowest values of a measurable attribute of the output of a process.


Loosening the pattern from the mold by jarring or knocking.

Rapping Bar

A pointed bar or rod made of steel or other metal, which is inserted vertically into a hole in a pattern, or driven into it, then struck with a hammer on alternate sides to cause vibration and loosening of the pattern from the sand.

Rapping Plate

Metal plate attached to a pattern to permit rapping for removal from the sand.

Rare Earth (RE)

Any of a group of 15 similar metals with atomic numbers 57 to 71. Also rare earth element, rare earth metal, lanthanide series, uncommon metals, Mischmetal.

Rare Gases

These include helium, argon, neon, krypton, xenon and radon.

Rat Tail

An expansion discontinuity in a sand casting, featured as a long, narrow, linear depression, resulting from sand expansion and minor buckling of the mold surface during filling of the mold.



Term usually employed in reference to adding new bonding material to used molding sand so that it can be used again to produce molds.

Receiving Ladle

A ladle placed in front of the cupola into which all metal is tapped. It acts as a mixer and reservoir and to smooth out metal flow to the pouring area. See Cupola, Ladle.


Reversing a pattern upon a face plate to permit turning the opposite face to the required shape.

Recovery Rate

Ratio of the number of parts scrapped to the total number of parts manufactured, expressed as a percentage.


A process whereby the distorted grain structure of cold-worked metals is replaced by a new, strain-free grain structure during annealing above a specific minimum temperature.

Recrystallization Temperature

The lowest temperature at which the distorted grain structure of a cold-worked metal is replaced by a new, strain-free grain structure during prolonged annealing. Time, purity of the metal, and prior deformation are important factors.

Reducing Flame

Flame burning with insufficient oxygen to provide complete combustion, resulting in the presence of carbon in the flame.


The removal of oxygen or addition of hydrogen.


An instrument for the ultrasonic testing of metals.


Heat-resistant material, usually non-metallic, used for furnace linings etc. The quality of resisting heat. Material usually made of ceramics, which is resistant to high temperatures, molten metal, and slag attack.

Refractory Clay

A clay which fuses at pce 25 (1590°C, 2894°F) or higher.


Regression Analysis

A statistical method of determining, or predicting, the value of a dependent variable, based on levels of one or more know independent variables.

Reject Rate

Ratio of the number of parts scrapped to the total number of parts manufactured, expressed as a percentage.

Release Agent (Parting Agent)

A material, e.g. silicone, stearate, oil, or wax for lubricating a die pattern or core box to facilitate easy removal of a casting, mold or core.

Relief Sprue

The term usually refers to a second sprue at opposite end of the runner to relieve pressure created during pouring operation.


The remaining flux density after the magnetizing force has been removed.


See Revert.

Repair Welding

Any welding carried out after delivery to the end user, i.e., after the casting has been in service.

Replicast Process (CS)

A ceramic shell process similar to the investment casting process. Uses a pattern made from expanded polystyrene (EPS) and is surrounded by a thin ceramic shell.


Any element remaining in any alloy following melting and casting which was not added to meet an analytical specification limit.

Residual Stress

See Stress, Residual.

Resin Binder

Any of the thermosetting types of resins used as binders for producing cores and shell molds, such as phenol and urea formaldehydes, melamines, furans (fufuryls and furfuryl alcohol), etc.

Resin-Coated Sand

Molding or core sand in which the binder is resin applied to the sand as a coating by either cold or hot coating. See Binder, Core Sand, Molding Sand.

Resolved Shear Stress

Stress operating on a crystallographic slip system.


A filtering device which covers the nose and mouth and prevents inhalation of dust or fumes; should have the U.S. Bureau of Mines certificate or approval for the specific contaminant being filtered out. Handkerchiefs and gauze masks give little or no protection.


Metal in the form of gates, sprues, risers or defective castings which are put back into the melting cycle. See Casting, Gate, Riser, Sprue.

Reverberatory Furnace

Melting unit with a roof arranged to deflect the flame and heat toward the hearth on which the metal to be melted rests.


Recycled sprues, gates, risers, defective castings and machine chips.See Casting, Gate, Riser, Sprue.

Reynolds Numbers

Used in hydraulics and in casting gating theory. A dimensionless value (dynamic viscosity / density) describing the fairly sudden shift of flow from laminar to turbulent. Re > 2000 represents turbulent flow. Laminar flow is seldom experienced in runner and gating systems.


Also called flow casting. A metal forming process in which a semi-solid metal is used to make the casting. The solid metal is heated to a partly liquid, softened state and then pressed into the final form. The finished part has closer tolerances, better surface finish, higher strength, and lighter weight than a similar part made with traditional casting techniques.



Hand- or power-operated device for removing large particles of sand or foreign material from foundry sand.


Gates, risers, loose pieces, etc., needed on the pattern to produce a sound casting. See Casting, Gate, Riser, Loose Pieces, Pattern.

Rimmed Steel

A low-carbon steel.

Ringelmann's Scale

In air pollution control, a black and white mesh scale reading from all clear to solid black, used to measure the density of smoke. Observer normally uses chart comparator 50 feet from the point where smoke emits.


A reservoir of molten metal that the casting can draw from to offset the shrinkage that is taking place as the metal solidifies. See Feeder.

Riser Contact

The connecting passage between a riser and a casting. See Casting, Riser.

Riser Distance

The length of the riser neck. The term is applied to side risers only. See Riser Neck.

Riser Gating

Gating system in which molten metal from the sprue enters a riser close to the mold cavity and then flows into the mold cavity. See Mold Cavity.

Riser Height

The distance from the top of the riser when liquid to the top of the riser neck. Riser height when sold is usually several inches less than when liquid because of contraction and loss of feed metal to the casting.

Riser Neck

The connecting passage between the riser and casting. Usually only the height and width or diameter of the riser neck are reported, although the shape can be equally important.

Riser Pad (Riser Contact)

An enlargement of the riser neck where it joins the casting. The purpose of the pad is to prevent the riser from breaking into the casting when it is struck or cut from the casting.

Riser, Blind

A riser that does not break through the top of the cope and is entirely surrounded by sand; opened to the atmosphere by means of a firecracker core.

Riser, Open

Conventional form of riser usually located at the heaviest section of the casting and extending through the entire height of the cope.

Riser, Side (Side Head)

A riser attached to the side of a casting.

Riser, Top (Top head)

A riser attached to the top surface of a casting.


Practice of running metal for the casting through the riser to help directional solidification.

Rockwell Hardness

See Hardness.

Rockwell Hardness Testing

Method of determining the indentation hardness by measuring the depth of residual penetration by a steel ball or a diamond cone. See Hardness.


Reinforcing the sand in a core with metal rods or shapes to strengthen parts of the core.

Rolling Over

Operation of turning flask over to reverse its position. Positioning the mold so that the pattern faces upward in order to be removed. See Core, Cope, Flask.

Rollover Board

A wood or metal plate on which the pattern is laid top face downward for ramming the drag half mold, the plate and half mold being turned over together before the joint is made. See Pattern.

Rollover Machine

A molding machine with which the flask is rolled over before the pattern is drawn from the mold.


Trapezoidal shaped piece that runs horizontally to the mold cavity and connects the Sprue base to the gate(s). See Gate, Sprue.

Runner Box

System into which molten metal is introduced.

Runner Extension

In a mold, part of a runner which extends beyond the farthest ingate as a blind end. It acts as a dirt trap and is sometimes vented. See Dirt Trap.

Runner Riser

A conventional runner, usually in the horizontal plane, which permits flow of molten metal to the in gate and is large enough to act as a reservoir to feed the casting.

Runner System (Gating)

The set of channels in a mould through which molten metal is poured to fill the mold cavity. The system normally consists of a vertical section (downgate or sprue) to the point where it joins the mold cavity (gate) and leading from the mould cavity further vertical channels (risers or feeders). See Riser, Feeder, Mold Cavity.


Metal flowing through a defect in the mold.


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Marion, IN 46952-3348
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