Z94.12.2 Foundry/Casting

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SAND. A loose, granular material resulting from the disintegration of rock. The name sand refers to the size of grain and not to mineral composition. Diameter of the individual grains can vary from approximately 6 to 270 mesh. Most foundry sands are made up principally of the mineral quartz (silica). The reason for this is that it is plentiful, refractory and cheap.

• bank sand. Sedimentary deposits, usually containing less than 5% clay.
• dune sand. Wind-blown deposits of sand found near large bodies of water.
• molding sands. Sands which contain over 5% natural clay, usually between 10% and 20%.
• silica sand. Although most foundry sands contain a high percentage of silica, the term silica sand is generally reserved for those that show a minimum of 95% silica content. Many high grade silica sands will analyze better than 99% pure silica.
• miscellaneous sands. These include zircon, olivine, CaCO3, black sands (lava grains), titanium minerals, etc.

SAND BLAST. Sand driven by a blast of compressed air (or steam); used to clean castings; to cut, polish or decorate glass or other hard substances; for cleaning building fronts, etc.

SAND CONTROL. Procedure whereby various properties of foundry sand, such as fineness, permeability, green strength, moisture content, etc., are adjusted to obtain castings free from blows, scabs, veins, and similar defects.

SAND INCLUSIONS. Sand which has loosened from the mold and become entrapped in the molten metal.

SAND RECLAMATION. Processing of used foundry sand by thermal or hydraulic methods, so that it may be used in place of new sand without substantially changing current foundry sand practice.

SAND SPUN PROCESS. A centrifugal casting technique for coating the mold with a thin layer of unbonded refractory parting material. Particularly useful for short lengths of cylindrical shapes.

SAND TOUGHNESS NUMBER. The product of deformation, times green compressive strength, times 1000. It is an indication of the workability of the sand mixture, and is usually expressed STN.

SCALING (SCALE). Surface oxidation, partially adherent layers of corrosion products, left on metals by heating or casting in oxidizing atmospheres.

SCRAP. Metal for remelting; includes scrapped machinery, rail, or structural steel and rejected castings.

SCREEN. A sieve or riddle with openings of a definite size. Sieves are used to separate the different fractions of a sand distribution or to remove agglomerated particles or lumps.

SEAM. A surface defect on a casting related to but of lesser degree than a cold shut; a ridge on the surface of a casting caused by a crack in the mold face.

SEGREGATION. (1) A sand problem which occurs during transportation in bulk or in sand silos or hoppers. It is difficult to reblend the various fractions into a homogeneous mix. (2) A casting defect which is evidenced by the concentration of alloying elements in specific regions usually as a result of the primary crystallization of one phase with the subsequent concentration of other elements in the remaining liquid.

SELFCURING BINDER. A material used in core making that sets up to form cured cores without heat or additional assistance.

SEPARATOR. A mechanical device which separates or grades materials into constituent parts, used in the foundry to remove fines from system sands and dust from the air.

SHAKE-OUT. The operation of removing castings from the mold. A mechanical unit for separating the molding material from the solidified metal casting.

SHAW PROCESS. A precision casting process which uses ceramic molds in five stages and using conventional metal patterns. The patented mold material microcrazes to produce sufficient permeability to pour castings weighing up to 1500 pounds (682 kg).

SHELL CORE PROCESS. Resin-coated sand is blown into a heated core box. The sand against the box hardens. The balance of the sand is drained out to make a hollow core.

SHELL MOLDING. A process for forming a mold from resin-bonded sand mixtures brought in contact with pre-heated (300°-500°F; 150°-260°C) metal patterns, resulting in a firm shell with cavity corresponding to the outline of the pattern. Also called Croning process.

SHOT BLASTING. A casting cleaning process which uses a metal abrasive (grit or shot) propelled by centrifugal or pneumatic force.

SHRINKAGE. Change in size as the metal passes from the fluid to the solid state in the mold.

SHRINKAGE, PATTERNMAKER'S. A scale divided in excess of standard measurement to allow for the difference in size between the casting and the corresponding mold cavity. Used by patternmakers to avoid calculations for shrinkage.(See PATTERNMAKER'S SHRINKAGE)

SIEVE ANALYSES. Determination of the partial size distribution of a molding sand expressed in terms of the weight retained on each of a series of standard sieves stacked according to the decreasing mesh size.

SILICA. Silicon dioxide, the prime ingredient of sharp sand and acid refractories.

SILICA BRICK. Refractory material of Ganister bonded with hydrated lime and fired at high temperature.

SILICA FLOUR. Material commonly produced by pulverizing pure grains of quartz sand in large ball mills. It is available in several mesh sizes, generally from 80 to 325 mesh. In analysis, it is 99% pure silica, and is commonly used in foundry practice for improving finish and increasing hot strength. It is also used in production of core and mold washes.

SILT. Very fine particles that pass a No. 270 mesh sieve, but which are not plastic or sticky when wet. (Between -50 and + 5 microns in size.)

SINTERING. The bonding of adjacent surfaces of particles or a compact by heating to a suitable temperature and cooling.

SLAG. A nonmetallic covering which forms on the molten metal as a result of the flux action in combining impurities contained in the original charge, some ash from the fuel, and any silica and clay eroded from the refractory lining. It is skimmed off prior to tapping the heat.

SLICK, SLICKER, SMOOTHER. A tool used for mending and smoothing the surfaces of a mold after withdrawal of pattern and before closing mold.

SLIP CASTING. In ceramics, the pouring of slip (water suspension of finely ground clay) into a plaster of Paris mold. After hardening, it is dried and fired.

SLURRY. A term loosely applied to any clay-like dispersion. It may be used to wash ladles or other refractory linings to impart a smoother surface, as a bonding addition to molding sand; as a thin loam over specially made molds; or as a mixture to fill in joints or cracks of a core, etc.

SLUSH CASTING. A casting made from an alloy that has a low melting point and freezes within a wide range of temperatures. The metal is poured into the mold, and brought into contact with all surfaces so as to form a shell of frozen metal; then the excess metal is poured out. Castings that consist of completely enclosed shells may be made by using a  definite quantity of metal and a closed mold.

SNAGGING. The process of rough cleaning castings by grinding.

SOLIDIFICATION. The physical process of change from a liquid to a solid state.

SOLIDIFICATION SHRINKAGE. The decrease in size accompanying the freezing of a molten metal.

SONIC TESTING. Using sound waves above audible frequency via a supersonic reflectoscope to measure the time sound waves take as they return from opposite sides of the casting. Defects return the waves in more, or less time.

SPARK TEST. A method of determining the approximate composition of steel by producing sparks on a grinding wheel.

SPIEGELEISEN. An alloy of iron and manganese used in basic and acid open hearth steel-making practices. Also can be used in cupola charges. A high manganese pig iron containing 15% to 20% Mn and 4.5% to 6.5% carbon.

SPIRAL FLUIDITY TEST. A quantitative test for determining the fluidity of an alloy by pouring molten metal into a mold with a long narrow spiral channel. The fluidity index is determined by the length of flow which the alloy achieved.

SPLASH CORE. A core or tile placed in a mold to prevent erosion of the mold at places where metal impinges with more than normal force. Splash cores are commonly used at the bottom of large rammed pouring basins, at the bottom of long downsprues, or at the ingates of large molds.

SPRUE. The vertical channel connecting the pouring basin with the skimming gate, if any, and the runner to the mold cavity, all of which together may be called the gate. In top-poured castings the sprue may also act as riser. Sometimes used as a generic term to cover all gates, risers, etc. returned to the melting unit for re-melting. Also applies to similar portions of master patterns, pattern dies, patterns, investment molds, and the finished castings.

SQUEEZE BOARD. A board used on the cope half of the mold to permit squeezing it on a jolt squeeze machine.

STANDARD PATTERN. A pattern of high-grade material and workmanship in daily use or used at frequent intervals. A pattern used as a master to make or check production patterns.

STICKER. A lump on the surface of a casting caused by a portion of the mold face sticking to the pattern. Also, a forming tool used in molding.

STREAMLINE FLOW. Steady flow of liquid metal with a minimum of changes in direction and subsequent eddying. True streamlined flow cannot be achieved in metal casting but disruptive turbulence can be eliminated.

STRESS, RESIDUAL. Those stresses set up in a metal as a result of non-uniform plastic deformation or the unequal cooling of a casting.

STYROFOAM PATTERN. Expendable pattern of foamed plastic, especially polystyrene used in producing castings by the full mold process. Especially useful for large automotive body dies or for art sculpture castings.

SUPERHEAT. Any increment of temperature above the melting point of a metal or alloy.

SWEEP. A template cut to the profile of the desired mold shape, which when revolved around a stake or spindle, produces that mold.

SWELL. A casting defect consisting of an increase in metal section due to the displacement of sand by metal pressure.

SWING FRAME GRINDER. A device for grinding large castings which must remain stationary. The grinder is suspended by a hoist because of its weight.

SYNTHETIC MOLDING SAND. Any sand compounded from selected individual materials which, when mixed together, produce a mixture of the proper physical and mechanical properties from which to make foundry molds.

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