1.
Chemical milling
–
Chemical milling or industrial etching is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. It is mostly used on metals, though materials are increasingly important. It was developed from armor-decorating and printing etching processes developed during the Renaissance as alternatives to engraving on metal, most modern chemical milling methods involve alkaline etchants, these may have been used as early as the first century CE. Armor etching, using mineral acids, was not developed until the fifteenth century. Etchants mixed from salt, charcoal, and vinegar were applied to plate armor that had painted with a maskant of linseed-oil paint. The etchant would bite into the areas, causing the painted areas to be raised into relief. Not long after, it used to etch trajectory information plates for cannon and artillery operators, paper would rarely survive the rigors of combat. Often such information was etched onto equipment such as daggers or shovels. In 1782, the discovery was made by John Senebier that certain resins lost their solubility to turpentine when exposed to light, photo-chemical milling was extensively used in the development of photography methods, allowing light to create impressions on metal plates. Etching has applications in the circuit board and semiconductor fabrication industries. It is also used in the industry to remove shallow layers of material from large aircraft components, missile skin panels. Etching is used widely to manufacture integrated circuits and Microelectromechanical systems, in addition to the standard, liquid-based techniques, the semiconductor industry commonly uses plasma etching. Chemical milling is normally performed in a series of five steps, cleaning, masking, scribing, etching, cleaning is the preparatory process of ensuring that the surface to be etched is free of contaminants which could negatively impact the quality of the finished part. An improperly cleaned surface could result in poor adhesion of the maskant, causing areas to be etched erroneously, the surface must be kept free from oils, grease, primer coatings, markings and other residue from the marking out process, scale, and any other foreign contaminants. For most metals, this step can be performed by applying a solvent substance to the surface to be etched, the material may also be immersed in alkaline cleaners or specialized de-oxidizing solutions. It is common practice in modern industrial chemical etching facilities that the workpiece never be directly handled after this process, masking is the process of applying the maskant material to the surface to ensure that only desired areas are etched. Liquid maskants may be applied via dip-masking, in which the part is dipped into a tank of maskant. Maskant may also be applied by flow coating, liquid maskant is flowed over the surface of the part, certain conductive maskants may also be applied by electrostatic deposition, where electrical charges are applied to particles of maskant as it is sprayed onto the surface of the material
2.
Melting
–
Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the energy of the solid increases, typically by the application of heat or pressure. At the melting point, the ordering of ions or molecules in the solid breaks down to an ordered state. Substances in the state generally have reduced viscosity as the temperature increases. An exception to this principle is the element sulfur, whose viscosity increases to a point due to polymerization, some organic compounds melt through mesophases, states of partial order between solid and liquid. Melting is therefore classified as a phase transition. Melting occurs when the Gibbs free energy of the liquid becomes lower than the solid for that material, the temperature at which this occurs is dependent on the ambient pressure. Low-temperature helium is the only exception to the general rule. Helium-3 has an enthalpy of fusion at temperatures below 0.3 K. Helium-4 also has a very slightly negative enthalpy of fusion below 0.8 K. This means that, at appropriate constant pressures, heat must be removed from these substances in order to melt them, among the theoretical criteria for melting, the Lindemann and of Born criteria are those most frequently used as a basis to analyse the melting conditions. The Lindemann melting criterion is supported by experimental data both for crystalline materials and for transitions in amorphous materials. The Born criterion is based on rigidity catastrophe caused by the elastic shear modulus. Under a standard set of conditions, the point of a substance is a characteristic property. The melting point is equal to the freezing point. However, under carefully created conditions, supercooling or superheating past the melting or freezing point can occur, water on a very clean glass surface will often supercool several degrees below the freezing point without freezing. Fine emulsions of pure water have been cooled to −38 degrees Celsius without nucleation to form ice, nucleation occurs due to fluctuations in the properties of the material. If the material is still there is often nothing to trigger this change. Thermodynamically, the liquid is in the metastable state with respect to the crystalline phase
3.
Metal
–
A metal is a material that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally malleable—that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible and ductile, about 91 of the 118 elements in the periodic table are metals, the others are nonmetals or metalloids. Some elements appear in both metallic and non-metallic forms, astrophysicists use the term metal to collectively describe all elements other than hydrogen and helium, the simplest two, in a star. The star fuses smaller atoms, mostly hydrogen and helium, to larger ones over its lifetime. In that sense, the metallicity of an object is the proportion of its matter made up of all chemical elements. Many elements and compounds that are not normally classified as metals become metallic under high pressures, the atoms of metallic substances are typically arranged in one of three common crystal structures, namely body-centered cubic, face-centered cubic, and hexagonal close-packed. In bcc, each atom is positioned at the center of a cube of eight others, in fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature, atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat, while this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond, Metals are usually inclined to form cations through electron loss, reacting with oxygen in the air to form oxides over various timescales. Examples,4 Na + O2 →2 Na2O2 Ca + O2 →2 CaO4 Al +3 O2 →2 Al2O3, the transition metals are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium, platinum and gold, do not react with the atmosphere at all, some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades. The oxides of metals are generally basic, as opposed to those of nonmetals, exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions. Painting, anodizing or plating metals are good ways to prevent their corrosion, however, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two form an electrochemical cell, and if the coating is less reactive than the coatee. Metals in general have high conductivity, high thermal conductivity. Typically they are malleable and ductile, deforming under stress without cleaving, in terms of optical properties, metals are shiny and lustrous. Sheets of metal beyond a few micrometres in thickness appear opaque, although most metals have higher densities than most nonmetals, there is wide variation in their densities, lithium being the least dense solid element and osmium the densest
4.
Semi-finished casting products
–
Semi-finished casting products are intermediate castings produced in a foundry that need further processing before being a finished good. There are four types, ingots, blooms, billets, ingots are large rough castings designed for storage and transportation. The shape usually resembles a rectangle or square with generous fillets and they are tapered, usually with the big-end-down. In the era of commercial wrought iron, blooms were slag-riddled iron castings poured in a bloomery before being worked into wrought iron, blooms are usually further processed via rotary piercing, structural shape rolling and profile rolling. Common final products include structural shapes, rails, rods, a billet is a length of metal that has a round or square cross-section, with an area less than 36 in2. Billets are created directly via continuous casting or extrusion or indirectly via hot rolling an ingot or bloom, billets are further processed via profile rolling and drawing. Final products include bar stock and wire, centrifugal casting is also used to produce short circular tubes as billets, usually to achieve a precise metallurgical structure. They are commonly used as cylinder sleeves where the inner and outer diameters are ground, because their size is not modified significantly, they are not always classified as semi-finished casting products. In copper production, a billet is a 30 long, about 8 diameter, a slab is a length of metal that is rectangular in cross-section. It is created directly by casting or indirectly by rolling an ingot on a slabbing mill. Slabs are usually further processed via flat rolling, skelping, common final products include sheet metal, plates, strip metal, pipes, and tubes
5.
Steel
–
Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and then Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product. Today, steel is one of the most common materials in the world and it is a major component in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft, ductile, and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and niobium. Additional elements are important in steel, phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
6.
Ingot
–
An ingot is a piece of relatively pure material, usually metal, that is cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products, Ingots usually require a second procedure of shaping, such as cold/hot working, cutting, or milling to produce a useful final product. Non-metallic and semiconductor materials prepared in bulk form may also be referred to as ingots, precious metal ingots can be used as currency, or as a currency reserve, as with gold bars. Metal, either pure or alloy, heated past its melting point, a special case are polycrystalline or single crystal ingots made by pulling from a molten melt. Single crystal ingots of materials are grown using methods such as the Czochralski process or Bridgeman technique, the boules may be either semiconductors or non-conducting inorganic compounds for industrial and jewelry use. Single crystal ingots of metal are produced in similar fashion to that used to high purity semiconductor ingots. Single crystal ingots of engineering metals are of interest due to their high strength due to lack of grain boundaries. The method of production is via single crystal dendrite and not via simple casting, in the United States, the brass and bronze ingot making industry started in the early 19th century. The US brass industry grew to be the number one producer by the 1850s, during colonial times the brass and bronze industries were almost non-existent because the British demanded all copper ore be sent to Britain for processing. Copper based alloy ingots weighed approximately 20 pounds, Ingots are manufactured by the freezing of a molten liquid in a mold. The manufacture of ingots has several aims, secondly, the shape and size of the mold is designed to allow for ease of ingot handling and downstream processing. Finally the mold is designed to minimize melt wastage and aid ejection of the ingot, a variety of designs exist for the mold, which may be selected to suit the physical properties of the liquid melt and the solidification process. Molds may exist in top, horizontal or bottom-up pouring and may be fluted or flat walled, the fluted design increases heat transfer owing to a larger contact area. Molds may be either solid massive design, sand cast or water-cooled shells, ingot molds are tapered to prevent the formation of cracks due to uneven cooling. Crack or void formation occurs as the liquid to solid transition has a volume change for a constant mass of material. Formation of these defects may render the cast ingot useless. The physical structure of a material is largely determined by the method of cooling. The rate of front advancement controls the time that dendrites or nuclei have to form in the solidification region, the width of the mushy zone in an alloy may be controlled by tuning the heat transfer properties of the mold, or adjusting the liquid melt alloy compositions
7.
Aluminium
–
Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
8.
Copper
–
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents, fungicides, and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, muscle, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings. Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
9.
Henry Bessemer
–
Sir Henry Bessemer was an English inventor, whose steelmaking process would become the most important technique for making steel in the nineteenth century. He also played a significant role in establishing the town of Sheffield as an industrial centre. Bessemer had been trying to reduce the cost of steelmaking for military ordnance and this made steel easier, quicker and cheaper to manufacture, and revolutionised structural engineering. Bessemer also made over 100 other inventions in the fields of iron, steel, unlike most inventors, he managed to bring his own projects to fruition and profited financially from their success. Bessemers father, Anthony, was born in London, but moved to Paris when he was 21 years old and he was an inventor who, while engaged by the Paris Mint, made a machine for making medallions that could produce steel dies from a larger model. He became a member of the French Academy of Science, for his improvements to the microscope when he was 26. He was forced to leave Paris by the French Revolution, there he invented a process for making gold chains, which was successful, and enabled him to buy a small estate in the village of Charlton, near Hitchin in Hertfordshire, where Henry was born. The invention from which Bessemer made his first fortune was a series of six steam-powered machines for making bronze powder, as he relates in his autobiography, he examined the bronze powder made in Nuremberg which was the only place where it was made at the time. He then copied and improved the product and made it capable of being made on a production line. It was an example of reverse engineering where a product is analysed. The process was kept secret, with members of his immediate family having access to the factory. It was a widely used alternative to a patent, and such trade secrets are used today. The Nuremberg powder, which was made by hand, retailed in London for £5 12s per pound and he reduced the price to half a crown. The profits from sale of the paint allowed him to pursue his other inventions, Bessemer patented a method for making a continuous ribbon of plate glass in 1848, but it was not commercially successful. He gained experience in designing furnaces, which was to be of use for his new steel-making process. Henry Bessemer worked on the problem of manufacturing cheap steel for production from 1850 to 1855 when he patented his method. On 24 August 1856 Bessemer first described the process to a meeting of the British Association in Cheltenham which he titled The Manufacture of Iron Without Fuel and it was published in full in The Times. The Bessemer process involved using oxygen in air blown through molten pig iron to burn off the impurities, james Nasmyth had been working on a similar idea for some time prior to this
10.
Bessemer converter
–
The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron before the development of the open hearth furnace. The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron, the oxidation also raises the temperature of the iron mass and keeps it molten. Related decarburizing with air processes had been used outside Europe for hundreds of years, one such process has existed since the 11th century in East Asia, where the scholar Shen Kuo describes its use in the Chinese iron and steel industry. In the 17th century, accounts by European travelers detailed its possible use by the Japanese, the modern process is named after its inventor, the Englishman Henry Bessemer, who took out a patent on the process in 1856. The process was said to be discovered in 1851 by the American inventor William Kelly. The process using a basic refractory lining is known as the basic Bessemer process or Gilchrist–Thomas process after the English discoverers Percy Gilchrist and these oxides either escape as gas or form a solid slag. The refractory lining of the converter also plays a role in the conversion — clay linings are used there is little phosphorus in the raw material - this is known as the acid Bessemer process. When the phosphorus content is high, dolomite, or sometimes magnesite and these are also known as Gilchrist-Thomas converters, after their inventor, Sidney Gilchrist Thomas. In order to produce steel with desired properties, additives such as spiegeleisen, when the required steel had been formed, it was poured into ladles and then transferred into moulds while the lighter slag was left behind. The conversion process, called the blow, was completed in approximately 20 minutes, during this period the progress of the oxidation of the impurities was judged by the appearance of the flame issuing from the mouth of the converter. The modern use of methods of recording the characteristics of the flame greatly aided the blower in controlling final product quality. After the blow, the metal was recarburized to the desired point and other alloying materials were added. A Bessemer converter could treat a heat of 5 to 30 tons at a time and they were usually operated in pairs, one being blown while another was being filled or tapped. Before the Bessemer process, Western Europe and the United States relied on the process to reduce the carbon content of white cast iron. It was possible to make low-quality puddled steel, but the process was difficult to control, high-quality steel was made by the reverse process of adding carbon to carbon-free wrought iron, usually imported from Sweden. The manufacturing process, called the process, consisted of heating bars of wrought iron together with charcoal for periods of up to a week in a long stone box. The blister steel was put in a crucible with wrought iron and melted, up to 3 tons of expensive coke was burnt for each ton of steel produced. Such steel when rolled into bars was sold at £50 to £60 a long ton, the most difficult and work-intensive part of the process, however, was the production of wrought iron done in finery forges in Sweden
11.
Refractory
–
A refractory material is a material that retains its strength at high temperatures. Refractory materials are used in linings for furnaces, kilns, incinerators and they are also used to make crucibles and moulds for casting glass and metals and for surfacing flame deflector systems for rocket launch structures. Today, the iron- and steel-industry uses approximately 70% of all refractories produced, refractory materials must be chemically and physically stable at high temperatures. Depending on the environment, they must be resistant to thermal shock, be chemically inert, and/or have specific ranges of thermal conductivity. The oxides of aluminium, silicon and magnesium are the most important materials used in the manufacturing of refractories, another oxide usually found in refractories is the oxide of calcium. Fire clays are also used in the manufacture of refractories. Refractories must be according to the conditions they face. Some applications require special refractory materials, zirconia is used when the material must withstand extremely high temperatures. Silicon carbide and carbon are two other materials used in some very severe temperature conditions, but they cannot be used in contact with oxygen, as they will oxidize. Binary compounds such as tungsten carbide or boron nitride can be very refractory, hafnium carbide is the most refractory binary compound known, with a melting point of 3890 °C. The ternary compound tantalum hafnium carbide has one of the highest melting points of all known compounds, Refractories can be classified on the basis of chemical composition, method of manufacture, physical form or according to their applications, fusion temperature. Acidic refractories consist of acidic materials like alumina and silica. They are generally not attacked or affected by acidic materials, and they include substances such as silica, alumina, and fire clay brick refractories. Notable reagents that can attack both alumina and silica are hydrofluoric acid, phosphoric acid, and fluorinated gases, at high temperatures, acidic refractories may also react with limes and basic oxides. These are used in areas where slags and atmosphere are either acidic or basic and are stable to both acids and bases. The main raw materials belong to, but are not confined to, common examples of these materials are alumina, chromia and carbon. These are used in areas where slags and atmosphere are basic, they are stable to alkaline materials, the main raw materials belong to the RO group to which magnesia is a very common example. Other examples include dolomite and chrome-magnesia, for the first half of the twentieth century, the steel making process used artificial periclase as a lining material for the furnace
12.
Tundish
–
The word tundish originates from a shallow wooden dish with an outlet channel, fitting into the bunghole of a tun or cask and forming a kind of funnel for filling it. These were originally used in brewing, the term is still used today in plumbing, where a funnel or hopper is filled by an outlet pipe above it. This is often provided for intermittent overflows, or where an air gap is required, in metal casting, a tundish is a broad, open container with one or more holes in the bottom. It is used to feed molten metal into an ingot mould so as to avoid splashing, metallic remains left inside a tundish are known as tundish skulls and need to be removed, typically by mechanical means. A casting tundish is lined with refractory bricks specific to the metal which is being cast
13.
Molding (process)
–
Molding or moulding is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have made using a pattern or model of the final object. A mold or mould is a block that is filled with a liquid or pliable material such as plastic, glass, metal. The liquid hardens or sets inside the mold, adopting its shape, a mold is the counterpart to a cast. The very common bi-valve molding process uses two molds, one for half of the object. Piece-molding uses a number of different molds, each creating a section of a complicated object and this is generally only used for larger and more valuable objects. The manufacturer who makes the molds is called the moldmaker, a release agent is typically used to make removal of the hardened/set substance from the mold easier. Typical uses for molded plastics include molded furniture, molded household goods, molded cases, and structural materials
14.
Hydrostatics
–
Fluid statics or hydrostatics is the branch of fluid mechanics that studies incompressible fluids at rest. It encompasses the study of the conditions under which fluids are at rest in stable equilibrium as opposed to fluid dynamics, hydrostatics are categorized as a part of the fluid statics, which is the study of all fluids, incompressible or not, at rest. Hydrostatics is fundamental to hydraulics, the engineering of equipment for storing, transporting and using fluids and it is also relevant to geophysics and astrophysics, to meteorology, to medicine, and many other fields. Some principles of hydrostatics have been known in an empirical and intuitive sense since antiquity, by the builders of boats, cisterns, aqueducts and fountains. Archimedes is credited with the discovery of Archimedes Principle, which relates the force on an object that is submerged in a fluid to the weight of fluid displaced by the object. The fair cup or Pythagorean cup, which dates from about the 6th century BC, is a technology whose invention is credited to the Greek mathematician. It was used as a learning tool, the cup consists of a line carved into the interior of the cup, and a small vertical pipe in the center of the cup that leads to the bottom. The height of this pipe is the same as the line carved into the interior of the cup, the cup may be filled to the line without any fluid passing into the pipe in the center of the cup. However, when the amount of fluid exceeds this fill line, due to the drag that molecules exert on one another, the cup will be emptied. Herons fountain is a device invented by Heron of Alexandria that consists of a jet of fluid being fed by a reservoir of fluid. The fountain is constructed in such a way that the height of the jet exceeds the height of the fluid in the reservoir, the device consisted of an opening and two containers arranged one above the other. The intermediate pot, which was sealed, was filled with fluid, trapped air inside the vessels induces a jet of water out of a nozzle, emptying all water from the intermediate reservoir. Pascal made contributions to developments in both hydrostatics and hydrodynamics, due to the fundamental nature of fluids, a fluid cannot remain at rest under the presence of a shear stress. However, fluids can exert pressure normal to any contacting surface, if a point in the fluid is thought of as an infinitesimally small cube, then it follows from the principles of equilibrium that the pressure on every side of this unit of fluid must be equal. If this were not the case, the fluid would move in the direction of the resulting force, thus, the pressure on a fluid at rest is isotropic, i. e. it acts with equal magnitude in all directions. This characteristic allows fluids to transmit force through the length of pipes or tubes, i. e. a force applied to a fluid in a pipe is transmitted, via the fluid, to the other end of the pipe. This principle was first formulated, in an extended form, by Blaise Pascal. In a fluid at rest, all frictional and inertial stresses vanish, when this condition of V =0 is applied to the Navier-Stokes equation, the gradient of pressure becomes a function of body forces only
15.
Rolling (metalworking)
–
In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness and to make the thickness uniform. The concept is similar to the rolling of dough, Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, if the temperature of the metal is below its recrystallization temperature, the process is known as cold rolling. In terms of usage, hot rolling processes more tonnage than any other manufacturing process, Roll stands holding pairs of rolls are grouped together into rolling mills that can quickly process metal, typically steel, into products such as structural steel, bar stock, and rails. Most steel mills have rolling mill divisions that convert the semi-finished casting products into finished products, there are many types of rolling processes, including ring rolling, roll bending, roll forming, profile rolling, and controlled rolling. The invention of the mill in Europe may be attributed to Leonardo da Vinci in his drawings. The earliest rolling mills in crude form but the basic principles were found in Middle East. Earliest rolling mills were slitting mills, which were introduced from what is now Belgium to England in 1590 and these passed flat bars between rolls to form a plate of iron, which was then passed between grooved rolls to produce rods of iron. The first experiments at rolling iron for tinplate took place about 1670, in 1697, Major John Hanbury erected a mill at Pontypool to roll Pontypool plates—blackplate. Later this began to be rerolled and tinned to make tinplate, the earlier production of plate iron in Europe had been in forges, not rolling mills. The slitting mill was adapted to producing hoops and iron with a half-round or other sections by means that were the subject of two patents of c. Some of the earliest literature on rolling mills can be traced back to Christopher Polhem in 1761 in Patriotista Testamente and he also explains how rolling mills can save on time and labor because a rolling mill can produce 10 to 20 or more bars at the same time. A patent was granted to Thomas Blockley of England in 1759 for the polishing and rolling of metals, another patent was granted in 1766 to Richard Ford of England for the first tandem mill. A tandem mill is one in which the metal is rolled in successive stands, Fords tandem mill was for hot rolling of wire rods, Rolling mills for lead seem to have existed by the late 17th century. Copper and brass were also rolled by the late 18th century, modern rolling practice can be attributed to the pioneering efforts of Henry Cort of Funtley Iron Mills, near Fareham, England. In 1783 a patent was issued to Henry Cort for his use of grooved rolls for rolling iron bars, with this new design mills were able to produce 15 times more output per day than with a hammer. Although Cort was not the first to use grooved rolls, he was first to combine the use of many of the best features of various ironmaking and shaping processes known at the time, thus modern writers have called him father of modern rolling. The first rail rolling mill was established by John Birkenshaw in 1820, with the advancement of technology in rolling mills the size of rolling mills grew rapidly along with the size products being rolled
16.
I-beam
–
An I-beam, also known as H-beam, W-beam, Universal Beam, Rolled Steel Joist, or double-T, is a beam with an I or H-shaped cross-section. The horizontal elements of the I are known as flanges, while the element is termed the web. I-beams are usually made of steel and are used in construction. The web resists shear forces, while the flanges resist most of the bending moment experienced by the beam, Beam theory shows that the I-shaped section is a very efficient form for carrying both bending and shear loads in the plane of the web. On the other hand, the cross-section has a capacity in the transverse direction. The method of producing an I-beam, as rolled from a piece of steel, was patented by Alphonse Halbou of the company Forges de la Providence in 1849. Bethlehem Steel was a supplier of rolled structural steel of various cross-sections in American bridge. Today, rolled cross-sections have been displaced in such work by fabricated cross-sections. There are two standard I-beam forms, Rolled I-beam, formed by hot rolling, cold rolling or extrusion, plate girder, formed by welding plates. I-beams are commonly made of steel but may also be formed from aluminium or other materials. A common type of I-beam is the rolled steel joist —sometimes incorrectly rendered as reinforced steel joist, british and European standards also specify Universal Beams and Universal Columns. These sections have parallel flanges, as opposed to the thickness of RSJ flanges which are seldom now rolled in the UK. Parallel flanges are easier to connect to and do away with the need for tapering washers, however, there has been some concern as to their rapid loss of strength in a fire if unprotected. I-beams are widely used in the industry and are available in a variety of standard sizes. Tables are available to allow selection of a suitable steel I-beam size for a given applied load. I-beams may be used both as beams and as columns, I-beams may be used both on their own, or acting compositely with another material, typically concrete. A beam under bending sees high stresses along the fibers that are farthest from the neutral axis. To prevent failure, most of the material in the beam must be located in these regions, comparatively little material is needed in the area close to the neutral axis
17.
Programmable logic controller
–
They were first developed in the automobile industry to provide flexible, ruggedised and easily programmable controllers to replace hard-wired relays and timers. Since then they have widely adopted as high-reliability automation controllers suitable for harsh environments. A PLC is an example of a hard real-time system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result. They can be designed for multiple arrangements of digital and analog inputs and outputs, extended temperature ranges, immunity to electrical noise, programs to control machine operation are typically stored in battery-backed-up or non-volatile memory. It was from the industry in the USA that the PLC was born. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was mainly composed of relays, cam timers, drum sequencers, when digital computers became available, being general-purpose programmable devices, they were soon applied to control sequential and combinatorial logic in industrial processes. However these early computers required specialist programmers and stringent operating environmental control for temperature, cleanliness, to meet these challenges the PLC was developed with several key attributes. In 1968 GM Hydra-Matic issued a request for proposals for a replacement for hard-wired relay systems based on a white paper written by engineer Edward R. Clark. The winning proposal came from Bedford Associates of Bedford, Massachusetts, the first PLC, designated the 084 because it was Bedford Associates eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product, Modicon, one of the people who worked on that project was Dick Morley, who is considered to be the father of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, later acquired by German Company AEG, and then by French Schneider Electric, one of the very first 084 models built is now on display at Schneider Electrics facility in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range until the 984 made its appearance, the automotive industry is still one of the largest users of PLCs. Early PLCs were designed to replace relay logic systems and these PLCs were programmed in ladder logic, which strongly resembles a schematic diagram of relay logic. This program notation was chosen to reduce training demands for the existing technicians, other early PLCs used a form of instruction list programming, based on a stack-based logic solver. Modern PLCs can be programmed in a variety of ways, from the ladder logic to programming languages such as specially adapted dialects of BASIC. Another method is state logic, a very high-level programming language designed to program PLCs based on state transition diagrams. As programming terminals evolved, it more common for ladder logic to be used, for the aforementioned reasons
18.
Slag
–
Slag is the glass-like by-product left over after a desired metal has been separated from its raw ore. Slag is usually a mixture of oxides and silicon dioxide. However, slags can contain metal sulfides and elemental metals, in nature, iron, copper, lead, nickel and other metals are found in impure states called ores, often oxidized and mixed in with silicates of other metals. During smelting, when the ore is exposed to high temperatures, Slag is the collection of compounds that are removed. In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities, in this case, the slag is termed synthetic. Ferrous and non-ferrous smelting processes produce different slags, the smelting of copper and lead in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron-silicate-based slags. Slag from steel mills in ferrous smelting, on the hand, is designed to minimize iron loss and so mainly contains oxides of calcium, silicon, magnesium. Any sandy component or quartz component of the original ore automatically carries through the process as silicon dioxide. As the slag is channeled out of the furnace, water is poured over it and this rapid cooling, often from a temperature of around 2,600 °F, is the start of the granulating process. This process causes several chemical reactions to take place within the slag, the water carries the slag in its slurry format to a large agitation tank, from where it is pumped along a piping system into a number of gravel based filter beds. The filter beds then retain the slag granules, while the drains away and is returned to the system. During the Bronze Age of the Mediterranean there were a vast number of metallurgical processes in use. A slag by-product of such workings was a colorful, glassy and it was primarily blue or green and was formerly chipped away and melted down to make glassware products and jewelry. It was also ground into powder to add to glazes for use in ceramics, some of the earliest such uses for the by-products of slag have been found in ancient Egypt. Historically, the re-smelting of iron ore slag was common practice, during the early 20th century, iron ore slag was also ground to a powder and used to make agate glass, also known as slag glass. Ground granulated slag is used in concrete in combination with Portland cement as part of a blended cement. Ground granulated slag reacts with water to produce cementitious properties, concrete containing ground granulated slag develops strength over a longer period, leading to reduced permeability and better durability. Since the unit volume of Portland cement is reduced, this concrete is less vulnerable to alkali-silica, the slag can also be used to create fibers used as an insulation material called slag wool
19.
Carbon
–
Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
20.
Boiling
–
Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F, boiling water is used as a method of making it potable by killing microbes that may be present. Clostridium spores can survive this treatment, but as the infection caused by this microbe is not water-borne, boiling is also used in cooking. Foods suitable for boiling vegetables, starchy foods such as rice, noodles and potatoes, eggs, meats, sauces, stocks. As a cooking method it is simple and suitable for large scale cookery, tough meats or poultry can be given a long, slow cooking and a nutritious stock is produced. Disadvantages include loss of water-soluble vitamins and minerals, commercially prepared foodstuffs are sometimes packed in polythene sachets and sold as boil-in-the-bag products. Nucleate boiling is characterized by the growth of bubbles or pops on a heated surface, in general, the number of nucleation sites are increased by an increasing surface temperature. An irregular surface of the vessel or additives to the fluid can create additional nucleation sites, while an exceptionally smooth surface, such as plastic. Under these conditions, a liquid may show boiling delay. As the boiling surface is heated above a temperature, a film of vapor forms on the surface. Since this vapor film is less capable of carrying heat away from the surface. The point at which this occurs is dependent on the characteristics of boiling fluid, transition boiling may be defined as the unstable boiling, which occurs at surface temperatures between the maximum attainable in nucleate and the minimum attainable in film boiling. If a surface heating the liquid is significantly hotter than the liquid then film boiling will occur, where a layer of vapor. This condition of a vapor film insulating the surface from the liquid characterizes film boiling, in distillation, boiling is used in separating mixtures. This is possible because the rising from a boiling fluid generally has a ratio of components different from that in the liquid. The elimination of micro-organisms by boiling follows first-order kinetics—at high temperatures it is achieved in time and at lower temperatures. Boiling does not ensure the elimination of all micro-organisms, the bacterial spores Clostridium can survive at 100 °C but are not water-borne or intestine affecting, thus for human health, complete sterilization of water is not required. Though the boiling point decreases with increasing altitude, it is not enough to affect the disinfecting process, boiling is the method of cooking food in boiling water, or other water-based liquids such as stock or milk
21.
Silicon
–
Silicon is a chemical element with symbol Si and atomic number 14. A hard and brittle crystalline solid with a metallic luster. It is a member of group 14 in the table, along with carbon above it and germanium, tin, lead. It is not very reactive, although more reactive than germanium, Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earths crust. It is most widely distributed in dusts, sands, planetoids, over 90% of the Earths crust is composed of silicate minerals, making silicon the second most abundant element in the Earths crust after oxygen. Most silicon is used commercially without being separated, and often with little processing of the natural minerals, such use includes industrial construction with clays, silica sand, and stone. Silicate is used in Portland cement for mortar and stucco, and mixed with sand and gravel to make concrete for walkways, foundations. Silicates are used in whiteware ceramics such as porcelain, and in traditional quartz-based soda-lime glass, Silicon compounds such as silicon carbide are used as abrasives and components of high-strength ceramics. Elemental silicon also has an impact on the modern world economy. Most free silicon is used in the refining, aluminium-casting. Silicon is the basis of the widely used synthetic polymers called silicones, Silicon is an essential element in biology, although only tiny traces are required by animals. However, various sea sponges and microorganisms, such as diatoms and radiolaria, silica is deposited in many plant tissues, such as in the bark and wood of Chrysobalanaceae and the silica cells and silicified trichomes of Cannabis sativa, horsetails and many grasses. Silicon is a solid at room temperature, with a point of 1,414 °C. Like water, it has a density in a liquid state than in a solid state and it expands when it freezes. With a relatively high conductivity of 149 W·m−1·K−1, silicon conducts heat well. In its crystalline form, pure silicon has a gray color, like germanium, silicon is rather strong, very brittle, and prone to chipping. Silicon, like carbon and germanium, crystallizes in a cubic crystal structure with a lattice spacing of 0.5430710 nm. The outer electron orbital of silicon, like that of carbon, has four valence electrons, the 1s, 2s, 2p and 3s subshells are completely filled while the 3p subshell contains two electrons out of a possible six
-2_NT.PNG)
