A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, removing the mold material after the metal has solidified as it cools; the most common metals processed are cast iron. However, other metals, such as bronze, steel and zinc, are used to produce castings in foundries. In this process, parts of desired shapes and sizes can be formed. In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, allowing it to cool and solidify; the solidified part is known as a casting, ejected or broken out of the mold to complete the process. Casting is most used for making complex shapes that would be difficult or uneconomical to make by other methods. Melting is performed in a furnace. Virgin material, external scrap, internal scrap, alloying elements are used to charge the furnace. Virgin material refers to commercially pure forms of the primary metal used to form a particular alloy.
Alloying elements are either pure forms of an alloying element, like electrolytic nickel, or alloys of limited composition, such as ferroalloys or master alloys. External scrap is material from other forming processes such as forging, or machining. Internal scrap consists of gates, defective castings, other extraneous metal oddments produced within the facility; the process includes melting the charge, refining the melt, adjusting the melt chemistry and tapping into a transport vessel. Refining is done to remove deleterious gases and elements from the molten metal to avoid casting defects. Material is added during the melting process to bring the final chemistry within a specific range specified by industry and/or internal standards. Certain fluxes may be used to separate the metal from slag and/or dross and degassers are used to remove dissolved gas from metals that dissolve certain gasses. During the tap, final chemistry adjustments are made. Several specialised furnaces are used to heat the metal.
Furnaces are refractory-lined vessels that contain the material to be melted and provide the energy to melt it. Modern furnace types include electric arc furnaces, induction furnaces, cupolas and crucible furnaces. Furnace choice is dependent on the alloy. For ferrous materials EAFs, induction furnaces are used. Reverberatory and crucible furnaces are common for producing aluminium and brass castings. Furnace design is a complex process, the design can be optimized based on multiple factors. Furnaces in foundries can be any size, ranging from small ones used to melt precious metals to furnaces weighing several tons, designed to melt hundreds of pounds of scrap at one time, they are designed according to the type of metals. Furnaces must be designed based on the fuel being used to produce the desired temperature. For low temperature melting point alloys, such as zinc or tin, melting furnaces may reach around 500 °C. Electricity, propane, or natural gas are used to achieve these temperatures. For high melting point alloys such as steel or nickel-based alloys, the furnace must be designed for temperatures over 1,600 °C.
The fuel used to reach these high temperatures can be coke. The majority of foundries specialize in a particular metal and have furnaces dedicated to these metals. For example, an iron foundry may use a cupola, induction furnace, or EAF, while a steel foundry will use an EAF or induction furnace. Bronze or brass foundries use crucible furnaces or induction furnaces. Most aluminium foundries use either electric resistance or gas heated crucible furnaces or reverberatory furnaces. Degassing is a process that may be required to reduce the amount of hydrogen present in a batch of molten metal. Gases can form in metal castings in one of two ways: by physical entrapment during the casting process or by chemical reaction in the cast material. Hydrogen is a common contaminant for most cast metals, it forms from water vapor or machine lubricants. If the hydrogen concentration in the melt is too high, the resulting casting will be porous. Porosity seriously deteriorates the mechanical properties of the metal.
An efficient way of removing hydrogen from the melt is to bubble a dry, insoluble gas through the melt by purging or agitation. When the bubbles go up in the melt, they bring it to the surface. Chlorine, nitrogen and argon are used to degas non-ferrous metals. Carbon monoxide is used for iron and steel. There are various types of equipment. Alternatively, the presence of hydrogen can be measured by determining the density of a metal sample. In cases where porosity still remains present after the degassing process, porosity sealing can be accomplished through a process called metal impregnating. In the casting process, a pattern is made in the shape of the desired part. Simple designs can be made in solid pattern. More complex designs are made in two parts, called split patterns. A split pattern has a top or upper section, called a cope, a bottom or lower section called a drag. Both solid and split patterns can have cores inserted to complete the final part shape. Cores are used to create hollow areas in the mold.
Where the cope and drag separates is called the parting line. When making a pattern it is best to taper the edges so that the pattern c
In classical architecture rustication is a range of masonry techniques giving visible surfaces a finish that contrasts in texture with the smoothly finished, squared-block masonry surfaces called ashlar. The visible face of each individual block is cut back around the edges to make its size and placing clear. In addition the central part of the face of each block may be given a deliberately rough or patterned surface. Rusticated masonry is "dressed", or squared off neatly, on all sides of the stones except the face that will be visible when the stone is put in place; this is given wide joints that emphasize the edges of each block, by angling the edges, or dropping them back a little. The main part of the exposed face may be worked flat and smooth or left with, or worked, to give a more or less rough or patterned surface. Rustication is used to give visual weight to the ground floor in contrast to smooth ashlar above. Though intended to convey a "rustic" simplicity, the finish is artificial, the faces of the stones carefully worked to achieve an appearance of a coarse finish.
Rustication was used in ancient times, but became popular in the revived classical styles of Italian Renaissance architecture and that of subsequent periods, above all in the lower floors of secular buildings. It remains in use in some modern architecture. Similar finishes are common in medieval architecture in castles and similar buildings, but here it arises from an unwillingness to spend the extra money required for ashlar masonry in a particular building, lacks the deliberate emphasis on the joints between blocks. Though it achieves a decorative effect, this is something of a by-product, the exploitation for architectural effect within a single building of contrasts between rusticated and ashlar surfaces is seen. In some buildings, such as the Palazzo Vecchio in Florence something other than cost-saving is at play, this may be the association of the technique with the display of power and strength, from its use in military architecture. Rough finishes on stone are very common in architecture outside the European tradition, but these too would not be called rustication.
For example, the bases of Japanese castles and other fortifications use rough stone very attractively. Although rustication is known from a few buildings of Greek and Roman antiquity, for example Rome's Porta Maggiore, the method first became popular during the Renaissance, when the stone work of lower floors and sometimes entire facades of buildings were finished in this manner, it was used for secular buildings, has always remained uncommon in churches through a lingering association with the architecture of military power. The earliest and most influential example is the Palazzo Medici Riccardi in Florence, built between 1444 and 1484, with two contrasting rusticated finishes; the ground floor has an irregular and genuinely rugged appearance, with a variation in the degree to which parts of the faces of blocks project from the wall, equalled later. Above, the rustication is to emphasize the individual blocks, the faces are all smooth and even. In Florence, Palazzo Strozzi, begun 1489, with large oblong rounded cushions, the front of the Pitti Palace, begun 1458, rusticated their whole facades in the same style.
These facades only used the classical orders in mullions and aedicules, with arched forms in rustication the main relief from the massive flat walls. The Palazzo Rucellai of the 1460s, begins to classicize such facades, using smooth-faced rustication throughout, except for the pilasters at each level. In Rome, Donato Bramante's Palazzo Caprini provided a standard model for the integration of rustication with the orders. Here the obvious strength of a blind arched arcade with emphatic voussoirs on the rusticated ground storey gave reassuring support to the upper storey's paired Doric columns standing on rusticated piers, set against a smooth wall; the first major Renaissance building in Spain, the Palace of Charles V in Granada, had a rusticated ground floor facade with regular rounded cushions. The technique was enthusiatically taken up by the next generation of Mannerist architects, with Giulio Romano in the lead. Most early examples of this "rustic" style are therefore built for sophisticated patrons in the leading centres of taste.
Giulio's Palazzo Stati Maccarani in Rome and Palazzo Te in Mantua expand the voussoirs still further, the courtyard in Mantua plays games with the technique, with some blocks ashlar, other projecting further than the rest, larger blocks placed higher than smaller ones. The Mannerist architectural writer Sebastiano Serlio and others of his generation enjoyed the play between rusticated and finished architectural elements. In the woodcut of a doorway from Serlio's 1537 treatise, the banded rustication of the wall is carried right across the attached column and the moldings of the doorway surround, binding together all the elements; the Italians brought in to expand the Palace of Fontainebleau introduced the technique to France. Its spread to Germany and England took longer, but by about the end of the 16th century it had reached all parts of Europe. In his Banqueting House in London, Inigo Jones gave a rusticated surface texture to emphasize the blocks on both storeys, to unify them behind his orders of pilasters and columns.
During the 18th century, following the Palladian revival, rustication was used on the ground floors of large buildings, as its contrived appea
A mint is an industrial facility which manufactures coins that can be used in currency. The history of mints correlates with the history of coins. In the beginning, hammered coinage or cast coinage were the chief means of coin minting, with resulting production runs numbering as little as the hundreds or thousands. In modern mints, coin dies are manufactured in large numbers and planchets are made into milled coins by the billions. With the mass production of currency, the production cost is weighed. For example, it costs the United States Mint much less than 25 cents to make a quarter, the difference in production cost and face value helps fund the minting body; the earliest metallic money did not consist of coins, but of unminted metal in the form of rings and other ornaments or of weapons, which were used for thousands of years by the Egyptian and Assyrian empires. Metals were well suited to represent wealth, owing to their great commodity value per unit weight or volume, their durability and rarity.
The best metals for coinage are gold, platinum, tin, aluminum, zinc and their alloys. The first mint was established in Lydia in the 7th century BC, for coining gold and electrum; the Lydian innovation of manufacturing coins under the authority of the state spread to neighboring Greece, where a number of city-states operated their own mints. Some of the earliest Greek mints were within city-states on Greek islands such as Crete. At about the same time and mints appeared independently in China and spread to Korea and Japan; the manufacture of coins in the Roman Empire, dating from about the 4th century BC influenced development of coin minting in Europe. The origin of the word "mint" is ascribed to the manufacture of silver coin at Rome in 269 BC at the temple of Juno Moneta; this goddess became the personification of money, her name was applied both to money and to its place of manufacture. Roman mints were spread across the Empire, were sometimes used for propaganda purposes; the populace learned of a new Roman Emperor when coins appeared with the new Emperor's portrait.
Some of the emperors who ruled only for a short time made sure. Ancient coins were made by striking between engraved dies; the Romans cast their larger copper coins in clay moulds carrying distinctive markings, not because they knew nothing of striking, but because it was not suitable for such large masses of metal. Casting is now used only by counterfeiters; the most ancient coins were cast in bulletshaped or conical moulds and marked on one side by means of a die, struck with a hammer. The "blank" or unmarked piece of metal was placed on a small anvil, the die was held in position with tongs; the reverse or lower side of the coin received a “rough incuse” by the hammer. A rectangular mark, a “square incuse,” was made by the sharp edges of the little anvil, or punch; the rich iconography of the obverse of the early electrum coins contrasts with the dull appearance of their reverse which carries only punch marks. The shape and number of these punches varied according to their weight-standard. Subsequently, the anvil was marked in various ways, decorated with letters and figures of beasts, still the anvil was replaced by a reverse die.
The spherical blanks soon gave place to lenticular-shaped ones. The blank was struck between cold dies. One blow was insufficient, the method was similar to that still used in striking medals in high relief, except that the blank is now allowed to cool before being struck. With the substitution of iron for bronze as the material for dies, about 300 AD, the practice of striking the blanks while they were hot was discarded. In the Middle Ages bars of metal were hammered out on an anvil. Portions of the flattened sheets were cut out with shears, struck between dies and again trimmed with shears. A similar method had been used in Ancient Egypt during the Ptolemaic Kingdom, but had been forgotten. Square pieces of metal were cut from cast bars, converted into round disks by hammering and struck between dies. In striking, the lower die was fixed into a block of wood, the blank piece of metal laid upon it by hand; the upper die was placed on the blank, kept in position by means of a holder round, placed a roll of lead to protect the hand of the operator while heavy blows were struck with a hammer.
An early improvement was the introduction of a tool resembling a pair of tongs, the two dies being placed one at the extremity of each leg. This avoided the necessity of readjusting the dies between blows, ensured greater accuracy in the impression. Minting by means of a falling weight intervened between the hand hammers and the screw press in many places. In Birmingham in particular this system became developed and was long in use. In 1553, the French engineer Aubin Olivier introduced screw presses for striking coins, together with rolls for reducing the cast bars and machines for punching-out round disks from flattened sheets of metal. 8 to 12 men took over from each other every quarter of an hour to maneuver the arms driving the screw which struck the medals. The rolls were driven by horses, mules or water-power. Henry II came up against hostility on the par
Integrated Authority File
The Integrated Authority File or GND is an international authority file for the organisation of personal names, subject headings and corporate bodies from catalogues. It is used for documentation in libraries and also by archives and museums; the GND is managed by the German National Library in cooperation with various regional library networks in German-speaking Europe and other partners. The GND falls under the Creative Commons Zero licence; the GND specification provides a hierarchy of high-level entities and sub-classes, useful in library classification, an approach to unambiguous identification of single elements. It comprises an ontology intended for knowledge representation in the semantic web, available in the RDF format; the Integrated Authority File became operational in April 2012 and integrates the content of the following authority files, which have since been discontinued: Name Authority File Corporate Bodies Authority File Subject Headings Authority File Uniform Title File of the Deutsches Musikarchiv At the time of its introduction on 5 April 2012, the GND held 9,493,860 files, including 2,650,000 personalised names.
There are seven main types of GND entities: LIBRIS Virtual International Authority File Information pages about the GND from the German National Library Search via OGND Bereitstellung des ersten GND-Grundbestandes DNB, 19 April 2012 From Authority Control to Linked Authority Data Presentation given by Reinhold Heuvelmann to the ALA MARC Formats Interest Group, June 2012