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Coining (mint)
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mint (coin)
A mint is an industrial facility which manufactures coin A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in orde ...s 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 coinage, 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 (United States coin), quarter (a 25 cent coin), and the difference in production cost and face value ... [...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 ... [...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 ... [...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 ton The short ton (symbol tn) is a measurement unit equal to . It is commonly used in the United States, where it is known simply as a ton, alt ... [...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 |
