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BACK DRAFT. A reverse taper which prevents removal of a pattern from the mold.
BACKING SAND. Reconditioned sand used for ramming main part of mold after pattern has been covered with facing sand.
BAGHOUSE. Large chamber for holding bags used in filtration of gases from a furnace to recover metal oxides and other solids suspended in the gases; one form of dust collector.
BAKED CORE. A core which has been heated through sufficient time and temperature to produce the desired physical properties attainable from its oxidizing or thermal-setting binders.
BAKED PERMEABILITY. The property of a molded mass of sand which when baked at a temperature above 230°F (110°C) and when cooled to room temperature permits passage through it of the gases resulting when molten metal is poured in a mold.
BAKED STRENGTH. Compressive, shear, tensile, or transverse strength of a molded sand mixture when baked at a temperature above 230°F (110°C) and then cooled to room temperature.
BANK SAND. Sedimentary deposits, usually containing less than five per cent clay, occurring in banks or pits, used in core making and in synthetic molding sands.
BARS (CLEATS). Ribs of metal or wood placed across the cope portion of a flask to help support the sand in the cope flask.
BASE PERMEABILITY. That physical property which permits gases to pass through packed dry sand grains containing no clay or other bonding substance.
BASIN. The enlarged mouth of the sprue into which the molten metal is first poured.
BED OR BED CHARGE. Initial charge of fuel in cupola upon which the melting is started.
BED COKE. First layer of coke placed in the cupola. Also the coke used as the foundation in constructing a large mold in flask or pit.
BENCH MOLDER. A craftsman who makes molds for smaller type castings, working at the molder's bench only.
BENTONITE. A colloidal clay derived from volcanic ash and employed as a binder in connection with synthetic sands, or added to ordinary natural (clay-bonded) sands where strength is required; western or sodium bentonite is found in Wyoming and South Dakota; also in the south central states which have quantities of southern or calcium.
BINDER. Artificially added bond (usually used to indicate other than clay) to foundry sand, such as cereal, pitch, resin, oil, sulphite by-product, etc.
BLACKING. Carbonaceous materials such as plumbage, graphite or powdered carbon, usually mixed with a binder and frequently carried in suspension in water or other liquid; used as a thin facing applied to surfaces of molds or cores to improve casting finish.
BLAST FURNACE. In ferrous metallurgy, a shaft furnace supplied with an air blast (usually hot) and used for producing pig iron by smelting iron ore in a continuous operation. The raw materials (iron ore, coke, and limestone) are charged at the top, and the molten pig iron and slag which collect at the bottom, are tapped out at intervals. In nonferrous metallurgy, a shaft type of vertical furnace is used for smelting coarse copper, lead, and tin ores; similar to the type used for smelting iron, but smaller.
BLAST PRESSURE. Pressure of air in blast pipe or wind belt of cupola, depending on location of indicating instrument; usually given in ounces per square inch or inches of water.
BLEEDER. A defect wherein a casting lacks completeness due to molten metal draining or leading out of some part of the mold cavity after pouring has stopped.
BLOWHOLE. Irregular shaped cavities with smooth walls produced in a casting when gas, entrapped while the mold is being filled, or evolved during solidification of the metal, fails to escape and is held in pockets.
BOB. A riser or feeder, usually blind, to provide molten metal to the casting during solidification, thereby preventing shrinkage cavities.
BOND, BONDING SUBSTANCE, OR BONDING AGENT. Any material other than water, which when added to foundry sands, imparts bond strength.
BOND CLAY. Any clay suitable for use as a bonding material.
BOND STRENGTH. Property of a foundry sand by virtue of which it offers resistance to deformation.
BOSS. A projection of circular cross-section on a casting. Usually intended for thickening a section so that it can be drilled and tapped.
BOT. A mass of clay used to stop the flow of metal from the taphole of the cupola.
BREAK-OFF CORE. A thin core connecting the riser and casting which, while not impeding the flow of metal, serves as a notch to assist in riser removal.
BUCKLE. An indentation in a casting, resulting from expansion of the sand. May be termed the start of an expansion defect.
BUMPER. Machine for ramming sand in a flask by repeated jarring or jolting.
BURNED SAND. Sand from which the binder or bond has been wholly or partially lost by contact with molten metal.
BUTT-OFF. Operation performed at times to supplement ramming by jolting, either hand or air rammer.
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