Foundry Casting

Casting is a widely used forming process in which a melt is poured into a mold or injected into a die and allowed to solidify. Since the solid takes the shape of the mold (with some shrinkage), the product is near net final shape. 

The final casting will be a polycrystalline solid whose microstructure will be largely determined by the structure of the dendrites that formed during the process as discussed previously. If a fine grain structure is required, additional nucleates may be added along with surface-active components to reduce the interfacial energy between the grains. 

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The products for these appHcations are fabricated from materials from brass mills (manufacturers of copper and alloy mill products), wire mills, and foundries (manufacturers of castings). Brass mill products consist of sheet, strip, plate, rod, bar, tube, pipe, forgings, extmsions, and mechanical wire. Wire mills make electrical wire. Foundry castings consist primarily of plumbing products and industrial valves and pumps. 

Giesserei,/. foundry, casting house founding, casting. betrieb, m. foundry practice, -eisen, n. foundry iron, foundry pig. -koks, m. foundry coke, -roheisen, n. foundry pig iron, foundry pig. -wesen, n. founding, foundry matters. 

In most foundries, casting sands are recycled internally until they can no longer be used for casting. At that time, many of the sands, such as those from iron foundries, are landfilled as nonhazardous waste. Casting sands used in the production of brass castings may be contaminated with lead and must be disposed of as hazardous waste. Methods which can be employed to reduce the toxicity or volume of these wastes are discussed below ... 

Different foundry casting techniques are used. Included are plastic-based binders mixed with sand. Various types of molds and cores are produced that include no-bake or cold-box, hot-box, shell, and oven-cured. Usual binders are phenolic, furan, and thermoset polyester. There is the foundry shell casting, also called dry-mix casting. It is a type of process used in the foundry industry, in which a mixture of sand and plastic (phenolic, thermoset polyester, etc.) is placed on to a preheated metal pattern (producing half a mold) causing the plastic to flow and build a thin shell over the pattern. Liquid plastic pre-coated sand is also used. After a short cure time at high temperature, the mold is stripped from its pattern and combined with a similar half produced by the same technique. Finished mold is then ready to receive the molten metal. Blowing a liquid plastic/sand mix in a core-box also produces shell molds. 

These two bronze pillars each measured between thirty-four and thirty-five feet and had a diameter of six feet at the base. The foundry cast the hollow pillars with a uniform wall thiekness of about three inches. A sort of chain ornamentation eovered the lower part of the eapitals, with representations of pomegranates in two rows of two hundred. At the very top was a lily-work motive, an imitation of the Egyptian lotus blossom. 

On the moulding side, a basic distinction is made between permanent and lost moulds. Foundries casting in permanent moulds, buy these metal moulds (dies) externally, but typically operate an in-house mould repair and maintenance shop. Foundries casting in lost moulds, often buy wooden, metal or plastic patterns (for their mould design) and operate an in-house pattern maintenance and repair shop. Moulds, cores and lost models are generally produced as part of the foundry process. 

Natural sand, which is found ready-mixed in nature, does not have the same high demands for mixing equipment as synthetic sand. It is mainly used in small-sized non-ferrous (e.g. copper) foundries and is not used in foundries casting iron and steel. 

On the basis of the stated criteria, the replacement of the eupola by induction or rotary furnaces may be eonsideied. The selection of induction or rotary furnaces is given priority over cold blast cupolas for small foundries casting a variety of products in several European countries (e g. Austria, Belgium (Flanders)). 

Chem. Descrip. Diisobutyl phthalate CAS 84-69-5 EINECS/ELINCS 201-553-2 Uses Plasticizer for thermoplastic and thermoset resins solvent, plasticizer in cellophane, resin-coated sand for foundry casting, org. peroxides food pkg. adhesives, coatings, paper, cellophane, rubber articles, l6Xlil6 ... 

Gressel MG (1997) An evaluation of a local exhaust ventilation control system for a foundry casting-cleaning operation. Am Ind Hygiene Assoc 58 254-258... 

Very large thick-gauge molds are usually made of atmospheric or foundry cast aluminum. A-360 series aluminum is easy to melt, pour, machine, weld, and has good corrosion resistance [10]. The mold is usually foundry sand. Properly cast aluminum is relatively free of surface and subsurface pores and... 

Uses Latex foam surfactant latex thread lubricant release agent for foundry casting additive to softeners, modifiers, particle treatments Features Chemically inert... 

E. Doetsch and H. DoHwa, "Economical and Process Technology Aspects of Cast Iron Melting," Electrowarmeint. 37(B3), B157 (1979), contains an economic comparison fuel-fired and electric iron foundry melting furnaces. 

A typical m el ter iastalled in a medium sized brass foundry contains 4500 kg of brass and its inductor is rated 500 kilowatts. Brass is an alloy containing copper and zinc. Zinc vaporizes at temperatures weU below the melting temperature of the alloy. The channel iaductor furnace s low bath temperature and relatively cool melt surface result in low metal loss and reduced environmental concerns. Large dmm furnaces have found use in brass and copper continuous casting installations. 

Most ferrous scrap is recycled in steelmaking processes by melting the scrap in either a basic oxygen or an electric arc furnace. However, a significant market exists for cast-iron products, which are also made by melting ferrous scrap. In 1991, world production of cast irons was estimated at nearly 3.9 X 10 t at over 14,000 iron foundries (15). 

Dryings of Castings and Other Products. The use of microwaves in the curing and drying of foundry cores is weU estabhshed (185). The best example is the use of microwaves for drying water-based core washes at 2450 MHz with up to 150 kW. These apphcations have not, however, found apphcation in manufacturing. Many similar drying apphcations have been examined (186,187). 

Technical molybdic oxide can be reduced by reaction of ferrosiUcon in a thermite-type reaction. The resulting product contains about 60% molybdenum and 40% iron. Foundries generally use ferromolybdenum for adding molybdenum to cast iron and steel, and steel mills may prefer ferromolybdenum to technical molybdic oxide for some types of steels. 

Foundry Resins. In the foundry industry, phenoHc resins are used as the binder for sand in the manufacture of sheU molds and cores. The two mating halves are joined by clamps or a bonding agent to form a sheU mold into which the molten metal is poured for castings. The sheU is formed by depositing a resin—sand mix on a hot metal pattern plate. After a certain period the pattern is inverted and the excess resin sand is removed. The sand particles are bonded by an oven cure, and the sheU is ejected from the pattern plate. 

Storage and Handling. Plutonium can be stored safely in dry air. Because of self-heating, storage accompanied by heat removal is advisable. The metal can be machined in moisture-free air containing at least 70 vol % Ar or He. Casting and foundry operations that requite melting of the metal must be carried out in vacuum or inert atmospheres and special containers. 

S, sand cast P, permanent mold cast D, pressure die cast. Aluminum and impurities constitute remainder. Table 22. Mechanical Properties of Aluminum Foundry Alloys ... 

Machinery nd Cupola. Cast Iron. This designation combines two cast-iron grades known as drop broken machinery cast and cupola cast. The former consists of clean, heavy machined cast iron that has been broken into pieces suitable for cupola charging. Cupola cast consists of a wide variety of cast-iron scrap, including automobile blocks and parts from agricultural and other machinery, in sizes suitable for the cupola. Machinery and cupola cast-iron scrap are primary sources of scrap for the iron foundries. 

Ferrous foundries consist of two types steel foundries in which electric furnaces (EAF and induction) are used, and iron foundries in which hot-blast cupolas and/or electric furnaces are used. Electric furnaces use virtually 100% scrap charges. Cupolas are shaft furnaces which use preheated air, coke, fluxes, and metallic charges. Scrap is over 90% of the metallic charge. Cupolas accounted for about 64% of total iron foundry scrap consumption in 1994 and electric furnaces accounted for about 34%. The balance was consumed by other furnaces, such as air furnaces. Iron foundry products have a high carbon content and the scrap charge usually contains a high percentage of cast iron or is used in combination with pig iron. 

K. E. Nicholas, The CO —Silicate Process in Foundries, Bfitish Cast Iron Research Association, Alvechurch, U.K., 1972. 

Prior to its addition to the aluminum casting alloys, the strontium metal is usually alloyed into the form of a master alloy. These master alloys are typically 10% Sr—90% A1 or 90% Sr—10% Al, and improve the dissolution and handling characteristics of strontium in the foundry. 

A second, more recently developed use for strontium metal is as an inoculant in ductile iron castings. Inoculants provide nuclei upon which graphite forms during the sohdification of cast iron, thus preventing the formation of white cast iron. Elkem Metals Company has commercialized a range of fine-sized foundry inoculants for iron castings. These inoculants, called superseed, are ferrosiUcon alloys containing 50 or 75% Si, 0.8% Sr. Most of the balance is iron. 

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