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Production Of Coins
Minting, coining or coinage is the process of manufacturing coins using a kind of stamping, the process used in both hammered coinage and milled coinage. This "stamping" process is different from the method used in cast coinage. A coin die is one of the two metallic pieces that are used to strike a coin, one per each side of the coin. A die contains an inverse version of the image to be ''struck'' on the coin. ''Striking'' a coin refers to pressing an image into the blank metal disc, or planchet, and is a term descended from the days when the dies were struck with hammers to deform the metal into the image of the dies. Modern dies made out of hardened steel are capable of producing many hundreds of thousands of coins before they are retired and defaced. Ancient coin dies Prior to the modern era, coin dies were manufactured individually by hand by artisans known as engravers. In demanding times, such as the crisis of the Roman Empire in the 3rd century, dies were still used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mint (coin)
A mint is an industrial facility which manufactures coins that can be used as currency. The history of mints correlates closely 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 when minting coins. For example, it costs the United States Mint much less than 25 cents to make a quarter (a 25 cent coin), and the difference in production cost and face value (called seigniorage) helps fund the minting body. Conversely, a U.S. penny ($0.01) cost $0.015 to make in 2016. History The first minted coins 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 th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lathe
A lathe () is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis. Lathes are used in woodturning, metalworking, metal spinning, thermal spraying, parts reclamation, and glass-working. Lathes can be used to shape pottery, the best-known design being the Potter's wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces and screw threads or helices. Ornamental lathes can produce three-dimensional solids of incredible complexity. The workpiece is usually held in place by either one or two ''centers'', at least one of which can typically be moved horizontally to accommodate varying workpiece lengths. Other work-holding methods include clamping the work about the axis of rotation using a chuck or col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annealing (metallurgy)
In metallurgy and materials science, annealing is a heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and reduce its hardness, making it more workable. It involves heating a material above its recrystallization temperature, maintaining a suitable temperature for an appropriate amount of time and then cooling. In annealing, atoms migrate in the crystal lattice and the number of dislocations decreases, leading to a change in ductility and hardness. As the material cools it recrystallizes. For many alloys, including carbon steel, the crystal grain size and phase composition, which ultimately determine the material properties, are dependent on the heating rate and cooling rate. Hot working or cold working after the annealing process alters the metal structure, so further heat treatments may be used to achieve the properties required. With knowledge of the composition and phase diagram, heat treatment can be used to ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incuse
This glossary of numismatics is a list of definitions of terms and concepts relevant to numismatics and coin collecting, as well as sub-fields and related disciplines, with concise explanations for the beginner or professional. Numismatics (ancient Greek: , meaning "monetary") is the scientific study of money and its history in all its varied forms. While numismatists are often characterized as studying coins, the discipline also includes the study of other types of money, such as banknotes, stock certificates, medals, medallions, and tokens (also referred to as exonumia). Sub-fields and related fields of numismatics include: * Exonumia, the study of coin-like objects such as token coins and medals, and other items used in place of legal currency or for commemoration. * Notaphily, the study of paper money or banknotes. * Philately, the study of postage stamps. * Scripophily, the study and collection of stocks and bonds. A B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubbing
Hubbing is a metalworking process that is used to make dies. It is a cold-working process, which means that it occurs well below the melting temperature of the metal being worked. Process In hubbing, a male hub (master) is created with a profile that will form an impression on the female piece. The male hub is generally hardened and the female die block softened by annealing to help form the impression. As the metal flows the face of the die block is deformed, and, generally, must be machined flat. The die block is often a cylinder that is reinforced with a surrounding steel ring during the hubbing process. Hubbing is usually less expensive than die sinking, i.e., machining the female die, and multiple dies can be made from the male hub. In the case of mild steel, a typical hubbing press exerts a pressure of approximately 1500 short tons-force per square inch (21 GPa) to transfer the image from a master hub into the master die. See also *Coining (metalworking) *Die maki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Treating
Heat treating (or heat treatment) is a group of industrial, thermal and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve the desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering, carburizing, normalizing and quenching. Although the term ''heat treatment'' applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding. Physical processes Metallic materials consist of a microstructure of small crystals called "gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reducing Machine
A Reducing Machine was a type of pantograph lathe used until the 21st century to manufacture coin dies. Prior to the machine's introduction, designs were cut by hand into metal dies by a specialist engraver. The reducing machine changed this by allowing artists to create designs on a larger surface area and then have them scaled down and cut into a die automatically. The most successful version of the machine, created by Victor Janvier, was used by mints all around the world including the US Mint who operated one as late as 2008 when it was replaced by CNC milling machines. History Contamin Pantograph From 1836 to 1867 the US Mint operated the first die-engraving pantograph invented by a now forgotten French inventor whom the machine is named after. It used a rotating cutter to copy a design. Hill Pantograph During the mid 1800s Englishman C. J. Hill developed a variation of the Contamin whereby the electrotype was traced horizontally using a treadle. Hill sold his idea to Wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable metallic form ( native metals). This led to very early human use in several regions, from circa 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, circa 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large scale (300 kton/year, in 1989) for uses in pencils, lubricants, and electrodes. Under high pressures and temperatures it converts to diamond. It is a weak conductor of heat and electricity. Types and varieties Natural graphite The principal types of natural graphite, each occurring in different types of ore deposits, are * Crystalline small flakes of graphite (or flake graphite) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken. When broken the edges can be irregular or angular; * Amorphous graphite: very fine flake graphite is sometimes called amorphous; * Lump graphite (or vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasticine
Plasticine is a putty-like modelling material made from calcium salts, petroleum jelly and aliphatic acids. Though originally a brand name for the British version of the product, it is now applied generically in English as a product category to other formulations. Plasticine is used for children's play and as a modelling medium for more formal or permanent structures. Because of its non-drying property, it is a material commonly chosen for stop-motion animation, including several Oscar-winning films by Nick Park. History Franz Kolb, owner of a pharmacy in Munich, Germany, invented an oil-based modelling clay in 1880. At the time, the city was a centre for the arts, and among Kolb's circle of friends were sculptors. They complained about how with the clay they were using for modelling, their sculptures would dry too fast and that — particularly in winter —, it was too difficult to work with. In order to commercialize his invention, he presented it to the Faber-Castel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Die Making
Tool and die makers are highly skilled crafters working in the manufacturing industries. Variations on the name include tool maker, toolmaker, die maker, diemaker, mold maker, moldmaker or tool jig and die-maker depending on which area of concentration or industry an individual works in. Tool and die makers work primarily in toolroom environments—sometimes literally in one room but more often in an environment with flexible, semipermeable boundaries from production work. They are skilled artisans ( craftspeople) who typically learn their trade through a combination of academic coursework and with substantial period of on-the-job training that is functionally an apprenticeship. They make jigs, fixtures, dies, molds, machine tools, cutting tools, gauges, and other tools used in manufacturing processes. Divisions The main divisions of the tool & die industry include: *Die casting * Dies * Fixtures *Forging * Gauges *Jigs *Metal working * Moulding Job description Traditionally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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