1.
The Machinist
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The Machinist is a 2004 psychological thriller film directed by Brad Anderson and written by Scott Kosar. The film stars Christian Bale and features Jennifer Jason Leigh, John Sharian, Aitana Sánchez-Gijón, the film is about Trevor Reznik, a machinist whose insomnia and psychological problems lead to a serious workplace accident involving a co-worker. After Reznik is fired, he goes into a spiral of paranoia. The film was well-received by critics, particularly for Bales performance and it is an international co-production of the United Kingdom, France, Spain, and the United States. Trevor Reznik is a machinist whose insomnia has led to his becoming emaciated and his appearance and behavior keeps his coworkers away, and they eventually turn against him when he is involved in an accident that causes his coworker, Miller, to lose his left arm. Trevor, who was distracted by an unfamiliar co-worker named Ivan, is blamed for the accident, no one at the factory knows of Ivan and there are no records of him. Trevor seems to find peace only with Stevie, a prostitute with genuine affection for him, and with Marie and he is haunted by brief flashes of recurring imagery, and things such as his car cigarette lighter take on a menacing air. A mysterious series of post-it notes appear on his refrigerator, depicting a game of hangman and these vague incidents send him further into paranoia, but he nonetheless attempts to establish a relationship with Marie. Meeting her at an amusement park, Trevor goes with her son Nicholas on a fun house ride called Route 666, no longer able to think clearly, Trevor suspects that the bizarre events are a concerted effort to drive him insane. These ideas are fed to him in small random clues, one of them is a picture of Ivan fishing with Trevors coworker Reynolds, which he discovers in Ivans wallet when its left behind in a pub. Another near-accident at work causes Trevor to lash out in rage at his co-workers, as a result, increasingly distracted and alienated, Trevor forgets to pay his utility bills and his electricity is disconnected. A dark, viscous liquid begins trickling out of the freezer, after several attempts to confront Ivan, Trevor tries to trace his license plate. He follows Ivans car to read its license plate, but runs out of gas during the pursuit. When a DMV clerk insists that personal information cannot be released unless a crime has been committed, Trevor throws himself in front of a car in order to accuse Ivan of committing a hit and run. He files a report with Ivans plate number on it, only to be baffled when he is told that the car in question is his own. He flees from the policemen and goes to Stevie, who clothes and washes him. Confused, Stevie says the picture is of Reynolds and Trevor and he goes to the airport diner, but is told by an unfamiliar waitress that theyve never had an employee named Maria. The waitress has served Trevor every day for a year, Trevor saying so little the waitress began to think he was a mute, in the films climax, Trevor sees Ivan take Nicholas into Trevors apartment and, fearing the worst, sneaks inside
2.
Machining
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Machining is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. Exactly what the part of the definition implies can vary. Machining is a part of the manufacture of metal products, but it can also be used on materials such as wood, plastic, ceramic. A person who specializes in machining is called a machinist, a room, building, or company where machining is done is called a machine shop. Machining can be a business, a hobby, or both, much of modern-day machining is carried out by computer numerical control, in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines. The precise meaning of the term machining has evolved over the past one, in the 18th century, the word machinist simply meant a person who built or repaired machines. This persons work was mostly by hand, using processes such as the carving of wood. At the time, millwrights and builders of new kinds of engines, such as James Watt or John Wilkinson, the noun machine tool and the verb to machine did not yet exist. Around the middle of the 19th century, the words were coined as the concepts that they described evolved into widespread existence. Therefore, during the Machine Age, machining referred to the machining processes, such as turning, boring, drilling, milling, broaching, sawing, shaping, planing, reaming. In current usage, the term machining without qualification usually implies the traditional machining processes, the three principal machining processes are classified as turning, drilling and milling. Other operations falling into miscellaneous categories include shaping, planing, boring, broaching and sawing, turning operations are operations that rotate the workpiece as the primary method of moving metal against the cutting tool. Lathes are the machine tool used in turning. Milling operations are operations in which the tool rotates to bring cutting edges to bear against the workpiece. Milling machines are the machine tool used in milling. Drilling operations are operations in which holes are produced or refined by bringing a rotating cutter with cutting edges at the lower extremity into contact with the workpiece, drilling operations are done primarily in drill presses but sometimes on lathes or mills. Burnishing is an example of a miscellaneous operation, burnishing produces no swarf but can be performed at a lathe, mill, or drill press. An unfinished workpiece requiring machining will need to have some material cut away to create a finished product, a finished product would be a workpiece that meets the specifications set out for that workpiece by engineering drawings or blueprints
3.
Machine tool
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A machine tool is a machine for shaping or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformation. Machine tools employ some sort of tool that does the cutting or shaping, all machine tools have some means of constraining the workpiece and provide a guided movement of the parts of the machine. Thus the relative movement between the workpiece and the tool is controlled or constrained by the machine to at least some extent. The precise definition of the machine tool varies among users. While all machine tools are machines that help people to make things, today machine tools are typically powered other than by human muscle, used to make manufactured parts in various ways that include cutting or certain other kinds of deformation. With their inherent precision, machine tools enabled the production of interchangeable parts. In this view of the definition, the term, arising at a time when all tools up till then had been hand tools and this lathe produced screw threads out of wood and employed a true compound slide rest. The mechanical toolpath guidance grew out of various concepts, First is the spindle concept itself. The machine slide, which has many forms, such as dovetail ways, box ways, Machine slides constrain tool or workpiece movement linearly. If a stop is added, the length of the line can also be accurately controlled, tracing, which involves following the contours of a model or template and transferring the resulting motion to the toolpath. Cam operation, which is related in principle to tracing but can be a step or two removed from the traced elements matching the reproduced elements final shape. For example, several cams, no one of which matches the desired output shape. Abstractly programmable toolpath guidance began with mechanical solutions, such as in musical box cams, later, electromechanical solutions and soon electronic solutions were added, leading to numerical control and computer numerical control. The value that machine tools added to these human talents is in the areas of rigidity, accuracy and precision, efficiency, as an example, it is physically possible to make interchangeable screws, bolts, and nuts entirely with freehand toolpaths. But it is practical to make them only with machine tools. In the 1930s, the U. S. National Bureau of Economic Research referenced the definition of a tool as any machine operating by other than hand power which employs a tool to work on metal. The narrowest colloquial sense of the reserves it only for machines that perform metal cutting—in other words. These processes are a type of deformation that produces swarf, thus presses are usually included in the economic definition of machine tools
4.
Mold maker
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A moldmaker or molder is a skilled trades worker who makes molds for use in metalworking and other manufacturing industries. It is sometimes regarded as a variety of the trade of the toolmaker, moldmakers are generally employed in foundries, where molds are used to cast products from metals such as aluminium and cast iron. Moldmakers may also be employed in the plastics, rubber or ceramics industries, the process of manufacturing molds is now often highly automated. While much of the processes involved in mold making use computer-controlled equipment for the actual manufacturing of molds. Moldmaking is still a skilled trade requiring expertise in manual machining, CNC machining, CNC wire EDM, CNC Ram EDM, surface grinding, hand polishing. Because of the skill and intense labor involved much of the mold making in the US has been outsourced to low wage countries. The majority of plastic and rubber parts that are in existence today are made using injection or transfer molds- requiring a mold to be manufactured by a moldmaker, the actual molding process is very highly automated
5.
Programmer
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A programmer, computer programmer, developer, dev, coder, or software engineer is a person who writes computer software. The term computer programmer can refer to a specialist in one area of programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst, a programmers primary computer language is often prefixed to these titles, and those who work in a web environment often prefix their titles with web. The use of the term programmer for these positions is sometimes considered an insulting or derogatory oversimplification. Because Babbages machine was never completed to a standard in her time. The first person to run a program on a functioning modern electronically based computer was computer scientist Konrad Zuse, the ENIAC programming team, consisting of Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman were the first regularly working programmers. International Programmers Day is celebrated annually on 7 January, in 2009, the government of Russia decreed a professional annual holiday known as Programmers Day to be celebrated on 13 September. It had also been an international holiday before that. Some of this section is from the Occupational Outlook Handbook, 2006–07 Edition, Computer programmers write, test, debug, and maintain the detailed instructions, called computer programs, that computers must follow to perform their functions. Programmers also conceive, design, and test logical structures for solving problems by computer, job titles and descriptions may vary, depending on the organization. Programmers work in many settings, including corporate information technology departments, big companies, small service firms. Many professional programmers also work for consulting companies at client sites as contractors, licensing is not typically required to work as a programmer, although professional certifications are commonly held by programmers. Programming is widely considered a profession, Programmers work varies widely depending on the type of business for which they are writing programs. For example, the involved in updating financial records are very different from those required to duplicate conditions on an aircraft for pilots training in a flight simulator. In most cases, several work together as a team under a senior programmer’s supervision. Programmers write programs according to the specifications determined primarily by more senior programmers, after the design process is complete, it is the job of the programmer to convert that design into a logical series of instructions that the computer can follow. The programmer codes these instructions in one of many programming languages, different programming languages are used depending on the purpose of the program. COBOL, for example, is used for business applications that typically run on mainframe and midrange computers, whereas Fortran is used in science
6.
Heavy equipment operator
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A heavy equipment operator operates heavy equipment used in engineering and construction projects. Typically only skilled workers may operate heavy equipment, and there is specialized training for learning to use heavy equipment, much publication about heavy equipment operators focuses on improving safety for such workers. The field of occupational medicine researches and makes recommendations about safety for these, various organizations set standards for training for heavy equipment operators. Such organizations typically offer what in the US is called effective safety training
7.
Production planning
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Production planning is the planning of production and manufacturing modules in a company or industry. It utilizes the resource allocation of activities of employees, materials and production capacity, different types of production methods, such as single item manufacturing, batch production, mass production, continuous production etc. have their own type of production planning. Production planning can be combined with production control into production planning and control, or it can be combined, Production planning is used in companies in several different industries, including agriculture, industry, amusement industry, etc. Production planning is a plan for the production, in which the facilities needed are determined and arranged. A production plan is made periodically for a time period. It can comprise the following activities, Determination of the product mix. Matching the required level of production to the existing resources, scheduling and choosing the actual work to be started in the manufacturing facility Setting up and delivering production orders to production facilities. In order to develop plans, the production planner or production planning department needs to work closely together with the marketing department. They can provide sales forecasts, or a listing of customer orders, the work is usually selected from a variety of product types which may require different resources and serve different customers. Therefore, the selection must optimize customer-independent performance measures such as cycle time, a critical factor in production planning is the accurate estimation of the productive capacity of available resources, yet this is one of the most difficult tasks to perform well. Production planning should take into account material availability, resource availability. Modern production planning methods and tools have developed since late 19th century. Under Scientific Management, the work for man or each machine is mapped out in advance. The origin of production planning back goes another century, Herrmann further describes the circumstances in which new methods for internal planning and control evolved, The first factories were quite simple and relatively small. They produced a number of products in large batches. Productivity gains came from using interchangeable parts to eliminate time-consuming fitting operations, through the late 1800s, manufacturing firms were concerned with maximizing the productivity of the expensive equipment in the factory. Keeping utilization high was an important objective, foremen ruled their shops, coordinating all of the activities needed for the limited number of products for which they were responsible. They hired operators, purchased materials, managed production, and delivered the product and they were experts with superior technical skills, and they planned production
8.
Numerical control
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Computer numerical control is the automation of machine tools by means of computers executing pre-programmed sequences of machine control commands. This is in contrast to machines that are controlled by hand wheels or levers. In modern CNC systems, the design of a mechanical part, the parts mechanical dimensions are defined using computer-aided design software, and then translated into manufacturing directives by computer-aided manufacturing software. The resulting directives are transformed into the specific commands necessary for a machine to produce the component. Since any particular component might require the use of a number of different tools – drills, saws, in other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design. The first NC machines were built in the 1940s and 1950s and these early servomechanisms were rapidly augmented with analog and digital computers, creating the modern CNC machine tools that have revolutionized the machining processes. Motion is controlled along multiple axes, normally at least two, and a spindle that moves in the Z. The position of the tool is driven by direct-drive stepper motor or servo motors in order to provide highly accurate movements, or in older designs, open-loop control works as long as the forces are kept small enough and speeds are not too great. On commercial metalworking machines, closed loop controls are standard and required in order to provide the accuracy, speed, as the controller hardware evolved, the mills themselves also evolved. Most new CNC systems built today are 100% electronically controlled, cNC-like systems are now used for any process that can be described as a series of movements and operations. CNC mills use computer controls to cut different materials and they are able to translate programs consisting of specific numbers and letters to move the spindle to various locations and depths. Many use G-code, which is a programming language that many CNC machines understand. These proprietary languages, while often simpler than G-code, are not transferable to other machines, CNC mills have many functions including face milling, shoulder milling, tapping, drilling and some even offer turning. Standard linear CNC mills are limited to 3 axis, but others may also have one or more rotational axes, today, CNC mills can have 4 to 6 axes. Lathes are machines that cut workpieces while they are rotated, CNC lathes are able to make fast, precision cuts, generally using indexable tools and drills. They are particularly effective for complicated programs designed to make parts that would be infeasible to make on manual lathes, CNC lathes have similar control specifications to CNC mills and can often read G-code as well as the manufacturers proprietary programming language. CNC lathes generally have two axes, but newer models have more axes, allowing for more advanced jobs to be machined, plasma cutting involves cutting a material using a plasma torch
9.
Mass production
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Mass production, flow production or continuous production is the production of large amounts of standardized products, including and especially on assembly lines. Together with job production and batch production, it is one of the three main production methods, the term mass production was popularized by a 1926 article in the Encyclopedia Britannica supplement that was written based on correspondence with Ford Motor Company. The New York Times used the term in the title of an article that appeared before publication of the Britannica article, the concepts of mass production are applied to various kinds of products, from fluids and particulates handled in bulk to discrete solid parts to assemblies of such parts. Mass production is a field, but it can generally be contrasted with craft production or distributed manufacturing. Mass production of fluid matter typically involves pipes with centrifugal pumps or screw conveyors to transfer raw materials or partially complete products between vessels, materials on pallets are handled with forklifts. Also used for handling heavy items like reels of paper, steel or machinery are electric overhead cranes, sometimes called bridge cranes because they span large factory bays. Mass production is intensive and energy intensive, as it uses a high proportion of machinery. It is also usually automated while total expenditure per unit of product is decreased, however, the machinery that is needed to set up a mass production line is so expensive that there must be some assurance that the product is to be successful to attain profits. One of the descriptions of mass production is that the skill is built into the tool, for example, in the 19th or early 20th century, this could be expressed as the craftsmanship is in the workbench itself. Later, once computerized control came about, jigs were obviated and this is the specialized capital required for mass production, each workbench and set of tools is different. Crossbows made with bronze parts were produced in China during the Warring States period, the Qin Emperor unified China at least in part by equipping large armies with these weapons, which were equipped with a sophisticated trigger mechanism made of interchangeable parts. Ships of war were produced on a scale at a moderate cost by the Carthaginians in their excellent harbors. The Venetians themselves also produced ships using prefabricated parts and assembly lines many centuries later, the Venetian Arsenal apparently produced nearly one ship every day, in what was effectively the worlds first factory which, at its height, employed 16,000 people. Mass production in the industry has been commonplace since the Gutenberg Bible was published using a printing press in the mid-15th century. In the Industrial Revolution simple mass production techniques were used at the Portsmouth Block Mills in England to make ships pulley blocks for the Royal Navy in the Napoleonic Wars. It was achieved in 1803 by Marc Isambard Brunel in cooperation with Henry Maudslay under the management of Sir Samuel Bentham, the Navy was in a state of expansion that required 100,000 pulley blocks to be manufactured a year. Bentham had already achieved remarkable efficiency at the docks by introducing power-driven machinery, by 1805, the dockyard had been fully updated with the revolutionary, purpose-built machinery at a time when products were still built individually with different components. A total of 45 machines were required to perform 22 processes on the blocks, the machines were almost entirely made of metal thus improving their accuracy and durability
10.
Woodcarver
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The phrase may also refer to the finished product, from individual sculptures to hand-worked mouldings composing part of a tracery. It therefore forms an important hidden element in the art history of many cultures, outdoor wood sculptures do not last long in most parts of the world, so it is still unknown how the totem pole tradition developed. Many of the most important sculptures of China and Japan in particular are in wood, and so are the majority of African sculpture. Wood is light and can take very fine detail so it is suitable for masks. It is also easier to work on than stone. Some of the finest extant examples of early European wood carving are from the Middle Ages in Germany, Russia, Italy and France, in England, many complete examples remain from the 16th and 17th century, where oak was the preferred medium. The gouge, a tool with a cutting edge used in a variety of forms and sizes for carving hollows, rounds. The coping saw, a saw that is used to cut off chunks of wood at once. The chisel, large and small, whose straight cutting edge is used for lines, the V-tool, used for parting, and in certain classes of flat work for emphasizing lines. The U-Gauge, a deep gouge with a U-shaped cutting edge. Sharpening equipment, such as stones and a strop, necessary for maintaining edges. The nature of the wood being carved limits the scope of the carver in wood is not equally strong in all directions. The direction in which wood is strongest is called grain and it is smart to arrange the more delicate parts of a design along the grain instead of across it. Less commonly, this principle is used in solid pieces of wood. Probably the two most common used for carving in North America are basswood and tupelo, both are hardwoods that are relatively easy to work with. Chestnut, butternut, oak, American walnut, mahogany and teak are also very good woods, while for fine work Italian walnut, sycamore maple, apple, pear, box or plum, are usually chosen. Decoration that is to be painted and of not too delicate a nature is often carved in pine, the type of wood is important. Hardwoods are more difficult to shape but have greater luster and longevity, softer woods may be easier to carve but are more prone to damage
11.
Steel
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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
12.
Aluminium
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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
13.
Brass
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Brass is a metal alloy made of copper and zinc, the proportions of zinc and copper can be varied to create a range of brasses with varying properties. It is an alloy, atoms of the two constituents may replace each other within the same crystal structure. By comparison, bronze is principally an alloy of copper and tin, however, bronze and brass may also include small proportions of a range of other elements including arsenic, phosphorus, aluminium, manganese, and silicon. The term is applied to a variety of brasses. Modern practice in museums and archaeology increasingly avoids both terms for objects in favour of the all-embracing copper alloy. It is also used in zippers, Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brass has higher malleability than bronze or zinc, the relatively low melting point of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard, the density of brass is 8.4 to 8.73 grams per cubic centimetre. Today, almost 90% of all alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet, Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the form and size. The general softness of brass means that it can often be machined without the use of cutting fluid, aluminium makes brass stronger and more corrosion-resistant. Aluminium also causes a highly beneficial hard layer of oxide to be formed on the surface that is thin, transparent. Tin has an effect and finds its use especially in seawater applications. Combinations of iron, aluminium, silicon and manganese make brass wear and tear resistant, to enhance the machinability of brass, lead is often added in concentrations of around 2%. Since lead has a melting point than the other constituents of the brass. The pattern the globules form on the surface of the brass increases the available surface area which in turn affects the degree of leaching. In addition, cutting operations can smear the lead globules over the surface and these effects can lead to significant lead leaching from brasses of comparatively low lead content
14.
Copper
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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
15.
Alloy
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An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are defined by a metallic bonding character, an alloy may be a solid solution of metal elements or a mixture of metallic phases. Intermetallic compounds are alloys with a stoichiometry and crystal structure. Zintl phases are sometimes considered alloys depending on bond types. Alloys are used in a variety of applications. In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties, in other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Examples of alloys are steel, solder, brass, pewter, duralumin, bronze, the alloy constituents are usually measured by mass. Alloys are usually classified as substitutional or interstitial alloys, depending on the arrangement that forms the alloy. They can be classified as homogeneous, or heterogeneous or intermetallic. An alloy is a mixture of elements, which forms an impure substance that retains the characteristics of a metal. Alloys are made by mixing two or more elements, at least one of which is a metal and this is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the base, they will be soluble. The mechanical properties of alloys will often be different from those of its individual constituents. A metal that is very soft, such as aluminium, can be altered by alloying it with another soft metal. Although both metals are soft and ductile, the resulting aluminium alloy will have much greater strength. Adding a small amount of carbon to iron trades its great ductility for the greater strength of an alloy called steel. Due to its strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful. By adding chromium to steel, its resistance to corrosion can be enhanced, creating stainless steel, while adding silicon will alter its electrical characteristics, producing silicon steel
16.
Vanadium
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Vanadium is a chemical element with symbol V and atomic number 23. It is a hard, silvery grey, ductile, and malleable transition metal, the elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer stabilizes the free metal somewhat against further oxidation. Four years later, however, he was convinced by other scientists that erythronium was identical to chromium, both names were attributed to the wide range of colors found in vanadium compounds. Del Rios lead mineral was later renamed vanadinite for its vanadium content, in 1867 Henry Enfield Roscoe obtained the pure element. Vanadium occurs naturally in about 65 different minerals and in fossil fuel deposits and it is produced in China and Russia from steel smelter slag, other countries produce it either from the flue dust of heavy oil, or as a byproduct of uranium mining. It is mainly used to produce specialty steel alloys such as high-speed tool steels, the most important industrial vanadium compound, vanadium pentoxide, is used as a catalyst for the production of sulfuric acid. Large amounts of ions are found in a few organisms. The oxide and some salts of vanadium have moderate toxicity. Particularly in the ocean, vanadium is used by life forms as an active center of enzymes. Vanadium was discovered by Andrés Manuel del Río, a Spanish-Mexican mineralogist, Del Río extracted the element from a sample of Mexican brown lead ore, later named vanadinite. He found that its salts exhibit a variety of colors. Later, Del Río renamed the element erythronium because most of the salts turned red upon heating, Del Río accepted Collet-Descotils statement and retracted his claim. In 1831, the Swedish chemist Nils Gabriel Sefström rediscovered the element in a new oxide he found working with iron ores. Later that same year, Friedrich Wöhler confirmed del Ríos earlier work, Sefström chose a name beginning with V, which had not been assigned to any element yet. He called the element vanadium after Old Norse Vanadís, because of the many beautifully colored chemical compounds it produces, in 1831, the geologist George William Featherstonhaugh suggested that vanadium should be renamed rionium after del Río, but this suggestion was not followed. The isolation of vanadium metal proved difficult, in 1831, Berzelius reported the production of the metal, but Henry Enfield Roscoe showed that Berzelius had in fact produced the nitride, vanadium nitride. Roscoe eventually produced the metal in 1867 by reduction of chloride, VCl2. In 1927, pure vanadium was produced by reducing vanadium pentoxide with calcium, the first large-scale industrial use of vanadium was in the steel alloy chassis of the Ford Model T, inspired by French race cars
17.
Zinc
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Zinc is a chemical element with the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table, in some respects zinc is chemically similar to magnesium, both elements exhibit only one normal oxidation state, and the Zn2+ and Mg2+ ions are of similar size. Zinc is the 24th most abundant element in Earths crust and has five stable isotopes, the most common zinc ore is sphalerite, a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States, Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity. Zinc metal was not produced on a large scale until the 12th century in India and was unknown to Europe until the end of the 16th century, the mines of Rajasthan have given definite evidence of zinc production going back to the 6th century BC. To date, the oldest evidence of pure zinc comes from Zawar, in Rajasthan, alchemists burned zinc in air to form what they called philosophers wool or white snow. The element was named by the alchemist Paracelsus after the German word Zinke. German chemist Andreas Sigismund Marggraf is credited with discovering pure metallic zinc in 1746, work by Luigi Galvani and Alessandro Volta uncovered the electrochemical properties of zinc by 1800. Corrosion-resistant zinc plating of iron is the application for zinc. Other applications are in batteries, small non-structural castings. A variety of compounds are commonly used, such as zinc carbonate and zinc gluconate, zinc chloride, zinc pyrithione, zinc sulfide. Zinc is an essential mineral perceived by the public today as being of exceptional biologic and public health importance, Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children, deficiency causes growth retardation, delayed sexual maturation, infection susceptibility, enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency, Zinc is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish.6 pm. The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C, above 210 °C, the metal becomes brittle again and can be pulverized by beating. Zinc is a conductor of electricity. For a metal, zinc has relatively low melting and boiling points, the melting point is the lowest of all the transition metals aside from mercury and cadmium. Many alloys contain zinc, including brass, Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium, and sodium
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Lead
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Lead is a chemical element with atomic number 82 and symbol Pb. When freshly cut, it is bluish-white, it tarnishes to a dull gray upon exposure to air and it is a soft, malleable, and heavy metal with a density exceeding that of most common materials. Lead has the second-highest atomic number of the stable elements. Lead is a relatively unreactive post-transition metal and its weak metallic character is illustrated by its amphoteric nature and tendency to form covalent bonds. Compounds of lead are found in the +2 oxidation state. Exceptions are mostly limited to organolead compounds, like the lighter members of the group, lead exhibits a tendency to bond to itself, it can form chains, rings, and polyhedral structures. Lead is easily extracted from its ores and was known to people in Western Asia. A principal ore of lead, galena, often bears silver, Lead production declined after the fall of Rome and did not reach comparable levels again until the Industrial Revolution. Nowadays, global production of lead is about ten million tonnes annually, Lead has several properties that make it useful, high density, low melting point, ductility, and relative inertness to oxidation. In the late 19th century, lead was recognized as poisonous, Lead is a neurotoxin that accumulates in soft tissues and bones, damaging the nervous system and causing brain disorders and, in mammals, blood disorders. A lead atom has 82 electrons, arranged in a configuration of 4f145d106s26p2. The combined first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, leads upper neighbor in group 14. This is unusual since ionization energies generally fall going down a group as an elements outer electrons become more distant from the nucleus, the similarity is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, and the relatively small radii of the elements after hafnium. The contraction is due to shielding of the nucleus by the lanthanide 4f electrons. The combined first four ionization energies of lead exceed those of tin, for this reason lead, unlike tin, mostly forms compounds in which it has an oxidation state of +2, rather than +4. Relativistic effects, which become particularly prominent at the bottom of the periodic table, as a result, the 6s electrons of lead become reluctant to participate in bonding, a phenomenon called the inert pair effect. A related outcome is that the distance between nearest atoms in crystalline lead is unusually long, the lighter group 14 elements form stable or metastable allotropes having the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals
19.
Manganese
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Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as an element in nature, it is often found in minerals in combination with iron. Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels, by the mid-18th century, Swedish chemist Carl Wilhelm Scheele had used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite contained a new element, johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon. Manganese phosphating is used for rust and corrosion prevention on steel, ionized manganese is used industrially as pigments of various colors, which depend on the oxidation state of the ions. The permanganates of alkali and alkaline earth metals are powerful oxidizers, Manganese dioxide is used as the cathode material in zinc-carbon and alkaline batteries. In biology, manganese ions function as cofactors for a variety of enzymes with many functions. Manganese enzymes are essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese also functions in the complex of photosynthetic plants. The element is a trace mineral for all known living organisms but is a neurotoxin. In larger amounts, and apparently with far greater effectiveness through inhalation, Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes like iron in water containing dissolved oxygen, naturally occurring manganese is composed of one stable isotope, 55Mn. Eighteen radioisotopes have been isolated and described, the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days. All of the radioactive isotopes have half-lives of less than three hours, and the majority of less than one minute. Manganese also has three meta states, Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion. 53Mn decays to 53Cr with a half-life of 3.7 million years, because of its relatively short half-life, 53Mn is relatively rare, produced by cosmic rays impact on iron. Manganese isotopic contents are combined with chromium isotopic contents and have found application in isotope geology
20.
Alloying elements
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An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are defined by a metallic bonding character, an alloy may be a solid solution of metal elements or a mixture of metallic phases. Intermetallic compounds are alloys with a stoichiometry and crystal structure. Zintl phases are sometimes considered alloys depending on bond types. Alloys are used in a variety of applications. In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties, in other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Examples of alloys are steel, solder, brass, pewter, duralumin, bronze, the alloy constituents are usually measured by mass. Alloys are usually classified as substitutional or interstitial alloys, depending on the arrangement that forms the alloy. They can be classified as homogeneous, or heterogeneous or intermetallic. An alloy is a mixture of elements, which forms an impure substance that retains the characteristics of a metal. Alloys are made by mixing two or more elements, at least one of which is a metal and this is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the base, they will be soluble. The mechanical properties of alloys will often be different from those of its individual constituents. A metal that is very soft, such as aluminium, can be altered by alloying it with another soft metal. Although both metals are soft and ductile, the resulting aluminium alloy will have much greater strength. Adding a small amount of carbon to iron trades its great ductility for the greater strength of an alloy called steel. Due to its strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful. By adding chromium to steel, its resistance to corrosion can be enhanced, creating stainless steel, while adding silicon will alter its electrical characteristics, producing silicon steel
21.
Plastic
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Plastic is a material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and can be molded into solid objects. Plastics are typically organic polymers of high mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, due to their relatively low cost, ease of manufacture, versatility, and imperviousness to water, plastics are used in an enormous and expanding range of products, from paper clips to spaceships. They have already displaced many traditional materials, such as wood, stone, horn and bone, leather, paper, metal, glass, and ceramic, in most of their former uses. In developed countries, about a third of plastic is used in packaging, other uses include automobiles, furniture, and toys. In the developing world, the ratios may be different - for example, the worlds first fully synthetic plastic was bakelite, invented in New York in 1907 by Leo Baekeland who coined the term plastics. Toward the end of the century, one approach to this problem was met with wide efforts toward recycling, the word plastic is derived from the Greek πλαστικός meaning capable of being shaped or molded, from πλαστός meaning molded. The common word plastic should not be confused with the technical adjective plastic, used for insulating parts in electrical fixtures, paper laminated products, thermally insulation foams. Problems include the probability of moldings naturally being dark colors, One of the most expensive commercial polymers. It forms the basis of artistic and commercial acrylic paints when suspended in water with the use of other agents, polytetrafluoroethylene – Heat-resistant, low-friction coatings, used in things like non-stick surfaces for frying pans, plumbers tape and water slides. It is more known as Teflon. Urea-formaldehyde – One of the aminoplasts and used as an alternative to phenolics. Used as an adhesive and electrical switch housings. Early plastics were bio-derived materials such as egg and blood proteins, in 1600 BC, Mesoamericans used natural rubber for balls, bands, and figurines. Treated cattle horns were used as windows for lanterns in the Middle Ages, materials that mimicked the properties of horns were developed by treating milk-proteins with lye. In the 1800s, as industrial chemistry developed during the Industrial Revolution, the development of plastics also accelerated with Charles Goodyears discovery of vulcanization to thermoset materials derived from natural rubber. Parkesine is considered the first man-made plastic, the plastic material was patented by Alexander Parkes, In Birmingham, UK in 1856. It was unveiled at the 1862 Great International Exhibition in London, parkesine won a bronze medal at the 1862 Worlds fair in London
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Rubber
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Natural rubber, also called India rubber or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. Malaysia and Indonesia are two of the leading rubber producers, forms of polyisoprene that are used as natural rubbers are classified as elastomers. Currently, rubber is harvested mainly in the form of the latex from the tree or others. The latex is a sticky, milky colloid drawn off by making incisions in the bark, the latex then is refined into rubber ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup, the coagulated lumps are collected and processed into dry forms for marketing. Natural rubber is used extensively in many applications and products, either alone or in combination with other materials, in most of its useful forms, it has a large stretch ratio and high resilience, and is extremely waterproof. The major commercial source of rubber latex is the Pará rubber tree. This species is preferred because it grows well under cultivation, a properly managed tree responds to wounding by producing more latex for several years. Congo rubber, formerly a source of rubber, came from vines in the genus Landolphia. These cannot be cultivated, and the drive to collect latex from wild plants was responsible for many of the atrocities committed under the Congo Free State. The latex exhibits the quality as the natural rubber from rubber trees. In the wild types of dandelion, latex content is low, in Nazi Germany, research projects tried to use dandelions as a base for rubber production, but failed. In collaboration with Continental Tires, IME began a pilot facility, many other plants produce forms of latex rich in isoprene polymers, though not all produce usable forms of polymer as easily as the Pará. Some of them require more processing to produce anything like usable rubber. Some produce other desirable materials, for example gutta-percha and chicle from Manilkara species, the term gum rubber is sometimes applied to the tree-obtained version of natural rubber in order to distinguish it from the synthetic version. The first use of rubber was by the cultures of Mesoamerica. The earliest archeological evidence of the use of latex from the Hevea tree comes the Olmec culture. The Pará rubber tree is indigenous to South America, charles Marie de La Condamine is credited with introducing samples of rubber to the Académie Royale des Sciences of France in 1736
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Glass
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Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, for example, window panes, tableware, and optoelectronics. The most familiar, and historically the oldest, types of glass are silicate glasses based on the chemical compound silica, the primary constituent of sand. The term glass, in usage, is often used to refer only to this type of material. Many applications of silicate glasses derive from their optical transparency, giving rise to their use as window panes. Glass can be coloured by adding metallic salts, and can also be painted and printed with vitreous enamels and these qualities have led to the extensive use of glass in the manufacture of art objects and in particular, stained glass windows. Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures, because glass can be formed or moulded into any shape, it has been traditionally used for vessels, bowls, vases, bottles, jars and drinking glasses. In its most solid forms it has also used for paperweights, marbles. Some objects historically were so commonly made of glass that they are simply called by the name of the material, such as drinking glasses. Porcelains and many polymer thermoplastics familiar from everyday use are glasses and these sorts of glasses can be made of quite different kinds of materials than silica, metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications, like glass bottles or eyewear, polymer glasses are a lighter alternative than traditional glass, silica is a common fundamental constituent of glass. In nature, vitrification of quartz occurs when lightning strikes sand, forming hollow, fused quartz is a glass made from chemically-pure SiO2. It has excellent resistance to shock, being able to survive immersion in water while red hot. However, its high melting-temperature and viscosity make it difficult to work with, normally, other substances are added to simplify processing. One is sodium carbonate, which lowers the transition temperature. The soda makes the glass water-soluble, which is undesirable, so lime, some magnesium oxide. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass, soda-lime glasses account for about 90% of manufactured glass. Most common glass contains other ingredients to change its properties, lead glass or flint glass is more brilliant because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index, iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium oxide can be used for glass that absorbs UV wavelengths
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Refractory metals
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Refractory metals are a class of metals that are extraordinarily resistant to heat and wear. The expression is used in the context of materials science, metallurgy. The definition of which belong to this group differs. The most common definition includes five elements, two of the period and three of the sixth period. They all share some properties, including a point above 2000 °C. They are chemically inert and have a high density. Their high melting points make powder metallurgy the method of choice for fabricating components from these metals, some of their applications include tools to work metals at high temperatures, wire filaments, casting molds, and chemical reaction vessels in corrosive environments. Partly due to the melting point, refractory metals are stable against creep deformation to very high temperatures. Most definitions of the refractory metals list the extraordinarily high melting point as a key requirement for inclusion. By one definition, a point above 4,000 °F is necessary to qualify. The melting point of the metals are the highest for all elements except carbon. This high melting point defines most of their applications, all the metals are body-centered cubic except rhenium which is hexagonal close-packed. Most physical properties of the elements in this group vary significantly because they are members of different groups, creep resistance is a key property of the refractory metals. This resistance against deformation at high temperatures makes the refractory metals suitable against strong forces at high temperature, for example in jet engines, the refractory metals show a wide variety of chemical properties because they are members of three distinct groups in the periodic table. They are easily oxidized, but this reaction is slowed down in the metal by the formation of stable oxide layers on the surface. Especially the oxide of rhenium is more volatile than the metal and they all are relatively stable against acids. Refractory metals are used in lighting, tools, lubricants, nuclear control rods, as catalysts. Because of their melting point, refractory metal components are never fabricated by casting
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Titanium
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Titanium is a chemical element with symbol Ti and atomic number 22. It is a transition metal with a silver color, low density. Titanium is resistant to corrosion in sea water, aqua regia, titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and it is named by Martin Heinrich Klaproth for the Titans of Greek mythology. The metal is extracted from its principal mineral ores by the Kroll, the most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride, a component of smoke screens and catalysts, and titanium trichloride, the two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, there are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant. Although they have the number of valence electrons and are in the same group in the periodic table. As a metal, titanium is recognized for its high strength-to-weight ratio and it is a strong metal with low density that is quite ductile, lustrous, and metallic-white in color. The relatively high melting point makes it useful as a refractory metal and it is paramagnetic and has fairly low electrical and thermal conductivity. Commercial grades of titanium have ultimate tensile strength of about 434 MPa, equal to that of common, low-grade steel alloys, titanium is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys achieve tensile strengths of over 1400 MPa, however, titanium loses strength when heated above 430 °C. Titanium is not as hard as some grades of heat-treated steel, it is non-magnetic, machining requires precautions, because the material might gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a limit that guarantees longevity in some applications. The metal is an allotrope of an hexagonal α form that changes into a body-centered cubic β form at 882 °C. The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls, similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but metastable at ambient pressures. This phase is usually hexagonal or trigonal and can be considered to be due to a soft longitudinal acoustic phonon of the β phase causing collapse of planes of atoms, like aluminium and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air. Titanium readily reacts with oxygen at 1,200 °C in air and it is, however, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation. When it first forms, this layer is only 1–2 nm thick but continues to grow slowly
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Beryllium
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Beryllium is a chemical element with symbol Be and atomic number 4. It is a rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars beryllium is depleted as it is fused and it is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl, as a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal. Beryllium improves many physical properties when added as an element to aluminium, copper, iron. Beryllium does not form oxides until it reaches high temperatures. Tools made of copper alloys are strong and hard and do not create sparks when they strike a steel surface. The high thermal conductivities of beryllium and beryllium oxide have led to their use in thermal management applications, Beryllium is a steel gray and hard metalloid that is brittle at room temperature and has a close-packed hexagonal crystal structure. It has exceptional stiffness and a high melting point. The modulus of elasticity of beryllium is approximately 50% greater than that of steel, the combination of this modulus and a relatively low density results in an unusually fast sound conduction speed in beryllium – about 12.9 km/s at ambient conditions. Other significant properties are high specific heat and thermal conductivity, which make beryllium the metal with the best heat dissipation characteristics per unit weight, in combination with the relatively low coefficient of linear thermal expansion, these characteristics result in a unique stability under conditions of thermal loading. Naturally occurring beryllium, save for slight contamination by cosmogenic radioisotopes, is essentially pure beryllium-9, Beryllium has a large scattering cross section for high-energy neutrons, about 6 barns for energies above approximately 10 keV. The single primordial beryllium isotope 9Be also undergoes a neutron reaction with neutron energies over about 1.9 MeV, to produce 8Be, thus, for high-energy neutrons, beryllium is a neutron multiplier, releasing more neutrons than it absorbs. Beryllium also releases neutrons under bombardment by gamma rays.8 seconds, β− is an electron, tritium is a radioisotope of concern in nuclear reactor waste streams. As a metal, beryllium is transparent to most wavelengths of X-rays and gamma rays, making it useful for the windows of X-ray tubes. Both stable and unstable isotopes of beryllium are created in stars, primordial beryllium contains only one stable isotope, 9Be, and therefore beryllium is a monoisotopic element. Radioactive cosmogenic 10Be is produced in the atmosphere of the Earth by the cosmic ray spallation of oxygen, 10Be accumulates at the soil surface, where its relatively long half-life permits a long residence time before decaying to boron-10. The production of 10Be is inversely proportional to activity, because increased solar wind during periods of high solar activity decreases the flux of galactic cosmic rays that reach the Earth
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Chromium
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Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin, sugar and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature. Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, protective, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, Chromium, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm. Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist
28.
Molybdenum
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Molybdenum is a chemical element with symbol Mo and atomic number 42. The name is from Neo-Latin molybdaenum, from Ancient Greek Μόλυβδος molybdos, meaning lead, molybdenum minerals have been known throughout history, but the element was discovered in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm, molybdenum does not occur naturally as a free metal on Earth, it is found only in various oxidation states in minerals. The free element, a metal with a gray cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of production of the element is used in steel alloys. Most molybdenum compounds have low solubility in water, but when molybdenum-bearing minerals contact oxygen and water, industrially, molybdenum compounds are used in high-pressure and high-temperature applications as pigments and catalysts. Molybdenum-bearing enzymes are by far the most common catalysts for breaking the chemical bond in atmospheric molecular nitrogen in the process of biological nitrogen fixation. At least 50 molybdenum enzymes are now known in bacteria and animals and these nitrogenases contain molybdenum in a form different from other molybdenum enzymes, which all contain fully oxidized molybdenum in a molybdenum cofactor. These various molybdenum cofactor enzymes are vital to the organisms, and molybdenum is an element for life in all higher eukaryote organisms. In its pure form, molybdenum is a metal with a Mohs hardness of 5.5. It has a point of 2,623 °C, of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten. Weak oxidation of molybdenum starts at 300 °C and it has one of the lowest coefficients of thermal expansion among commercially used metals. The tensile strength of molybdenum wires increases about 3 times, from about 10 to 30 GPa, there are 35 known isotopes of molybdenum, ranging in atomic mass from 83 to 117, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with masses of 92,94,95,96,97,98. Of these naturally occurring isotopes, only molybdenum-100 is unstable, molybdenum-98 is the most abundant isotope, comprising 24. 14% of all molybdenum. Molybdenum-100 has a half-life of about 1019 y and undergoes double beta decay into ruthenium-100, molybdenum isotopes with mass numbers from 111 to 117 all have half-lives of approximately 150 ns. All unstable isotopes of molybdenum decay into isotopes of niobium, technetium, as also noted below, the most common isotopic molybdenum application involves molybdenum-99, which is a fission product. It is a parent radioisotope to the short-lived gamma-emitting daughter radioisotope technetium-99m, in 2008, the Delft University of Technology applied for a patent on the molybdenum-98-based production of molybdenum-99
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Tungsten
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Tungsten, also known as wolfram, is a chemical element with symbol W and atomic number 74. The word tungsten comes from the Swedish language tung sten, which translates to heavy stone. Its name in Swedish is volfram, however, in order to distinguish it from scheelite, a hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth almost exclusively in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783 and its important ores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements discovered, melting at 3,422 °C,6,192 °F. Its high density is 19.3 times that of water, comparable to that of uranium and gold, polycrystalline tungsten is an intrinsically brittle and hard material, making it difficult to work. However, pure single-crystalline tungsten is more ductile, and can be cut with a hard-steel hacksaw, tungstens many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in TIG welding, superalloys, and radiation shielding. Tungstens hardness and high density give it military applications in penetrating projectiles, tungsten compounds are also often used as industrial catalysts. Tungsten is the metal from the third transition series that is known to occur in biomolecules. It is the heaviest element known to be essential to any living organism, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to animal life. In its raw form, tungsten is a hard metal that is often brittle. If made very pure, tungsten retains its hardness, and becomes malleable enough that it can be worked easily and it is worked by forging, drawing, or extruding. Tungsten objects are commonly formed by sintering. Of all metals in pure form, tungsten has the highest melting point, lowest vapor pressure, although carbon remains solid at higher temperatures than tungsten, carbon sublimes, rather than melts, so tungsten is considered to have a higher melting point. Tungsten has the lowest coefficient of expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons, alloying small quantities of tungsten with steel greatly increases its toughness. Tungsten exists in two crystalline forms, α and β. The former has a cubic structure and is the more stable form
30.
Inconel
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Inconel is a family of austenitic nickel-chromium-based superalloys. Inconel alloys are oxidation- and corrosion-resistant materials well suited for service in extreme environments subjected to pressure, when heated, Inconel forms a thick, stable, passivating oxide layer protecting the surface from further attack. Inconel’s high temperature strength is developed by solid solution strengthening or precipitation hardening, depending on the alloy, Inconel alloys are typically used in high temperature applications. It is sometimes referred to in English as Inco, common trade names for Inconel Alloy 625 include, Inconel 625, Chronin 625, Altemp 625, Haynes 625, Nickelvac 625 and Nicrofer 6020. The Inconel family of alloys was first developed in the 1940s by research teams at Wiggin Alloys, different Inconels have widely varying compositions, but all are predominantly nickel, with chromium as the second element. Inconel alloys are oxidation- and corrosion-resistant materials well suited for service in extreme environments subjected to high pressure, when heated, Inconel forms a thick and stable passivating oxide layer protecting the surface from further attack. Inconels high temperature strength is developed by solid solution strengthening or precipitation strengthening, depending on the alloy, in age-hardening or precipitation-strengthening varieties, small amounts of niobium combine with nickel to form the intermetallic compound Ni3Nb or gamma prime. Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures, the formation of gamma-prime crystals increases over time, especially after three hours of a heat exposure of 850 °C, and continues to grow after 72 hours of exposure. Inconel is a metal to shape and machine using traditional techniques due to rapid work hardening. After the first machining pass, work hardening tends to plastically deform either the workpiece or the tool on subsequent passes, for this reason, age-hardened Inconels such as 718 are machined using an aggressive but slow cut with a hard tool, minimizing the number of passes required. Alternatively, the majority of the machining can be performed with the workpiece in a solutionized form, external threads are machined using a lathe to single-point the threads or by rolling the threads in the solution treated condition using a screw machine. Inconel 718 can also be roll-threaded after full aging by using heat to 1,300 °F without increasing the grain size. Holes with internal threads are made by threadmilling, internal threads can also be formed using a sinker EDM. Cutting of a plate is often done with a waterjet cutter, new whisker-reinforced ceramic cutters are also used to machine nickel alloys. They remove material at a rate eight times faster than carbide cutters. Apart from these methods, Inconel parts can also be manufactured by selective laser melting, more often than machining, water-jet or laser, grinding is a preferred and economical method for forming Nickel alloy components to shape and finish. Due to the hardness of the used, the grinding wheels are not as affected by the material work hardening and remain sharp. Welding of some Inconel alloys can be due to cracking
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Haynes International
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The company specializes in corrosion-resistant and high-temperature alloys for the aerospace, chemical processing and industrial gas turbine industries. The company was founded by Elwood Haynes in 1912 in Kokomo, Indiana, Haynes had recently received a patent for a metal he created, which he named Stellite. In 1920, the company was purchased by Union Carbide, in 1922, the company invented its first alloy under the Hastelloy brand, derived from the first letters of the words Haynes Stellite Alloy. In 1927, Charles Lindbergs aircraft, the Spirit of St. Louis, in 1970, Cabot Corporation purchased the company. In 1989, the investment banking firm of Morgan, Lewis, Githens, in 1997, the Blackstone Group purchased the company. The debt incurred ultimately forced Haynes into bankruptcy in March 2004, in 1999, the company opened an office in Singapore, its first sales office in Asia. In 2004, the company acquired Branford Wire & Manufacturing of Mountain Home, in March 2007, Haynes completed a public equity offering. In addition to Kokomo, Haynes has manufacturing facilities in Arcadia, Louisiana, the Kokomo facility specializes in flat products, the Arcadia facility in tubular products, and the Mountain Home facility in wire products. The space shuttle’s engines have a total of 47 parts made from Haynes 188 alloy and 7 from Haynes Hastelloy B alloy, Hastelloy C-22 alloy is used for the fuel line bellows that assist in achieving takeoff. The companys revenues in fiscal year 2016 were derived from the following industries and these alloys are based on nickel and can survive in high-temperature, high-stress situations such as chemical reactors
32.
Superalloys
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The crystal structure is typically face-centered cubic austenitic. Examples of such alloys are Hastelloy, Inconel, Waspaloy, Rene alloys, Haynes alloys, Incoloy, MP98T, TMS alloys, superalloy development has relied heavily on both chemical and process innovations. Superalloys develop high temperature strength through solid solution strengthening, an important strengthening mechanism is precipitation strengthening which forms secondary phase precipitates such as gamma prime and carbides. Oxidation or corrosion resistance is provided by such as aluminium and chromium. The primary application for such alloys is in turbine engines, both aerospace and marine, because these alloys are intended for high temperature applications their creep and oxidation resistance are of primary importance. Nickel based superalloys have emerged as the material of choice for these applications, each of these additions has been chosen to serve a particular purpose in optimizing the properties for high temperature application. Creep resistance is dependent on slowing the speed of motion within a crystal structure. In modern Ni based superalloys, the γ’-Ni3 phase present acts as a barrier to dislocation motion. For this reason, this γ’ intermetallic phase, when present in high volume fractions, drastically increases the strength of these due to its ordered nature. The chemical additions of aluminum and titanium promote the creation of the γ’ phase, the γ’ phase size can be precisely controlled by careful precipitation strengthening heat treatments. In order to improve the resistance of these alloys, Al, Cr, B. The Al and Cr form oxide layers that passivate the surface, in addition to solid solution strengthening, if grain boundaries are present, certain elements are chosen for grain boundary strengthening. B and Zr tend to segregate to the boundaries which reduces the grain boundary energy and results in better grain boundary cohesion. For this reason, efforts have also put into developing Co based superalloys over the past several years. Despite that, traditional Co based superalloys have not found widespread usage because they have a strength at high temperature than Ni based superalloys. The main reason for this is that they appear to lack the γ’ precipitation strengthening that is so important in the high strength of Ni-based superalloys. A2006 report on metastable γ’-Co3 intermetallic compound with the L12 structure suggests Co based alloys as alternative to traditional Ni based superalloys, however this class of alloys was reported in a PhD thesis by C. S. Lee in 1971. The two-phase microstructure consists of cuboidal γ’ precipitates embedded in a continuous γ matrix and is morphologically identical to the microstructure observed in Ni based superalloys
33.
High speed steel
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High-speed steel is a subset of tool steels, commonly used in tool bits and cutting tools. It is often used in power-saw blades and drill bits and it is superior to the older high-carbon steel tools used extensively through the 1940s in that it can withstand higher temperatures without losing its temper. This property allows HSS to cut faster than high carbon steel, at room temperature, in their generally recommended heat treatment, HSS grades generally display high hardness and abrasion resistance compared with common carbon and tool steels. Although development of high speed steel began in the second half of the 19th century. These include hardened steels in China in 13th century BC, wootz steel manufactured in India around 350 BC and production of Damascus and Japanese layered steel blades in years 540 AD and 900 AD. High-speed properties of those steels would be coincidental and would be the result of local iron ores containing natural traces of tungsten or other favorable alloying components. In 1868 the English metallurgist Robert Forester Mushet developed Mushet steel and it consisted of 2% carbon,2. 5% manganese, and 7% tungsten. The major advantage of steel was that it hardened when air cooled from a temperature at which most steels had to be quenched for hardening. Over the next 30 years the most significant change was the replacement of manganese with chromium, the Taylor-White process was patented and created a revolution in the machining industries. Heavier machine tools with higher rigidity were needed to use the new steel to its advantage, prompting redesigns. The patent was hotly contested and eventually nullified, the first alloy that was formally classified as high-speed steel is known by the AISI designation T1, which was introduced in 1910. It was patented by Crucible Steel Co. at the beginning of the 20th century, the advances in molybdenum-based high speed steel during this period put them on par with and in certain cases better than tungsten-based high speed steels. This started with the use of M2 steel instead of T1 steel, high speed steels are alloys that gain their properties from either tungsten or molybdenum, often with a combination of the two. They belong to the Fe–C–X multi-component alloy system where X represents chromium, tungsten, molybdenum, vanadium, generally, the X component is present in excess of 7%, along with more than 0. 60% carbon. The alloying element percentages do not alone bestow the hardness-retaining properties, they also require appropriate high-temperature heat treatment to become true HSS, in the unified numbering system, tungsten-type grades are assigned numbers in the T120xx series, while molybdenum and intermediate types are T113xx. ASTM standards recognize 7 tungsten types and 17 molybdenum types, T1 The original HSS, it has been generally superseded by M2. Adding molybdenum, tungsten and chromium steel creates several alloys commonly called HSS, M1 M1 lacks some of the red-hardness properties of M2, but is less susceptible to shock and will flex more. M2 M2 is the standard and most widely used industrial HSS and it has small and evenly distributed carbides giving high wear resistance, though its decarburization sensitivity is a little bit high
34.
Tungsten carbide
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Tungsten carbide is a chemical compound containing equal parts of tungsten and carbon atoms. Tungsten carbide is approximately two times stiffer than steel, with a Youngs modulus of approximately 530–700 GPa, and is double the density of steel—nearly midway between that of lead and gold. It is comparable with corundum in hardness and can only be polished and finished with abrasives of superior hardness such as boron nitride and diamond powder, wheels. Tungsten is Swedish for heavy stone, colloquially among workers in various industries, tungsten carbide is often simply called carbide, despite the inaccuracy of the usage. Among the lay public, the popularity of tungsten carbide rings has also led to consumers calling the material tungsten. Tungsten carbide is prepared by reaction of metal and carbon at 1400–2000 °C. Other methods include a lower temperature fluid bed process that reacts either tungsten metal or blue WO3 with CO/CO2 mixture. WC can also be produced by heating WO3 with graphite, both compounds may be present in coatings and the proportions can depend on the coating method. At high temperatures WC decomposes to tungsten and carbon and this can occur during high-temperature thermal spray, e. g. in high velocity oxygen fuel, oxidation of WC starts at 500–600 °C. It is resistant to acids and is attacked by hydrofluoric acid/nitric acid mixtures above room temperature. It reacts with fluorine gas at temperature and chlorine above 400 °C and is unreactive to dry H2 up to its melting point. Finely powdered WC oxidizes readily in hydrogen peroxide aqueous solutions, at high temperatures and pressures it reacts with aqueous sodium carbonate forming sodium tungstate, a procedure used for recovery of scrap cemented carbide.5 µm·m−1·K−1. Tungsten carbide is extremely hard, ranking about 9 on Mohs scale and it has a Youngs modulus of approximately 530–700 GPa, a bulk modulus of 630–655 GPa, and a shear modulus of 274 GPa. It has a tensile strength of 344 MPa, an ultimate compression strength of about 2.7 GPa. The speed of a wave through a thin rod of tungsten carbide is 6220 m/s. Tungsten carbides low electrical resistivity of about 0.2 µΩ·m is comparable with that of some metals, WC is readily wetted by both molten nickel and cobalt. Investigation of the diagram of the W-C-Co system shows that WC. There are two forms of WC, a form, α-WC, and a cubic high-temperature form, β-WC
35.
Ceramic
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A ceramic is an inorganic, non-metallic, solid material comprising metal, non-metal or metalloid atoms primarily held in ionic and covalent bonds. This article gives an overview of ceramic materials from the point of view of materials science, the crystallinity of ceramic materials ranges from highly oriented to semi-crystalline, vitrified, and often completely amorphous. Most often, fired ceramics are either vitrified or semi-vitrified as is the case with earthenware, stoneware, varying crystallinity and electron consumption in the ionic and covalent bonds cause most ceramic materials to be good thermal and electrical insulators. With such a range of possible options for the composition/structure of a ceramic, the breadth of the subject is vast. Many composites, such as fiberglass and carbon fiber, while containing ceramic materials, are not considered to be part of the ceramic family. The earliest ceramics made by humans were pottery objects or figurines made from clay, either by itself or mixed with materials like silica, hardened, sintered. Later ceramics were glazed and fired to create smooth, colored surfaces, decreasing porosity through the use of glassy, ceramics now include domestic, industrial and building products, as well as a wide range of ceramic art. In the 20th century, new materials were developed for use in advanced ceramic engineering. The word ceramic comes from the Greek word κεραμικός, of pottery or for pottery, from κέραμος, potters clay, tile, the earliest known mention of the root ceram- is the Mycenaean Greek ke-ra-me-we, workers of ceramics, written in Linear B syllabic script. The word ceramic may be used as an adjective to describe a material, product or process, or it may be used as a noun, either singular, or, more commonly, as the plural noun ceramics. A ceramic material is an inorganic, non-metallic, often crystalline oxide, nitride or carbide material, some elements, such as carbon or silicon, may be considered ceramics. Ceramic materials are brittle, hard, strong in compression, weak in shearing and they withstand chemical erosion that occurs in other materials subjected to acidic or caustic environments. Ceramics generally can withstand high temperatures, such as temperatures that range from 1,000 °C to 1,600 °C. Glass is often not considered a ceramic because of its amorphous character. However, glassmaking involves several steps of the process and its mechanical properties are similar to ceramic materials. Traditional ceramic raw materials include minerals such as kaolinite, whereas more recent materials include aluminium oxide. The modern ceramic materials, which are classified as advanced ceramics, include silicon carbide, both are valued for their abrasion resistance, and hence find use in applications such as the wear plates of crushing equipment in mining operations. Advanced ceramics are used in the medicine, electrical, electronics industries. Crystalline ceramic materials are not amenable to a range of processing
36.
Diamond
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Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material and those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron, small amounts of defects or impurities color diamond blue, yellow, brown, green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earths mantle. Carbon-containing minerals provide the source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the Earths surface through deep volcanic eruptions by magma, Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earths mantle. An alternative, and completely different growth technique is chemical vapor deposition, several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have developed to distinguish natural diamonds, synthetic diamonds. The word is from the ancient Greek ἀδάμας – adámas unbreakable, the name diamond is derived from the ancient Greek αδάμας, proper, unalterable, unbreakable, untamed, from ἀ-, un- + δαμάω, I overpower, I tame. Diamonds have been known in India for at least 3,000 years, Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history, later in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, the most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials. The dispersion of light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology developed methods of grading diamonds, four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds, these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon and these conditions are met in two places on Earth, in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. The conditions for diamond formation to happen in the mantle occur at considerable depth corresponding to the requirements of temperature and pressure
37.
Engineering tolerance
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In engineering and safety, a physical distance or space, as in a truck, train or boat under a bridge as well as a train in a tunnel. In mechanical engineering the space between a bolt and a nut or a hole, etc, dimensions, properties, or conditions may have some variation without significantly affecting functioning of systems, machines, structures, etc. A variation beyond the tolerance is said to be noncompliant, rejected, a primary concern is to determine how wide the tolerances may be without affecting other factors or the outcome of a process. This can be by the use of principles, engineering knowledge. Experimental investigation is very useful to investigate the effects of tolerances, Design of experiments, formal engineering evaluations, a good set of engineering tolerances in a specification, by itself, does not imply that compliance with those tolerances will be achieved. Actual production of any product involves some inherent variation of input and output, measurement error and statistical uncertainty are also present in all measurements. With a normal distribution, the tails of measured values may extend well beyond plus and minus three standard deviations from the process average, appreciable portions of one tails might extend beyond the specified tolerance. The process capability of systems, materials, and products needs to be compatible with the engineering tolerances. Process controls must be in place and an effective Quality management system, such as Total Quality Management, a process capability index is used to indicate the relationship between tolerances and actual measured production. The choice of tolerances is also affected by the statistical sampling plan. This relates to the question of whether tolerances must be rigid or whether some small percentage of being out-of-tolerance may sometimes be acceptable. The alternative is that the best product has a measurement which is precisely on target, there is an increasing loss which is a function of the deviation or variability from the target value of any design parameter. The greater the deviation from target, the greater is the loss and this is described as the Taguchi loss function or quality loss function, and it is the key principle of an alternative system called inertial tolerancing. Research and development work conducted by M. Pillet and colleagues at the Savoy University has resulted in industry-specific adoption, recently the publishing of the French standard NFX 04-008 has allowed further consideration by the manufacturing community. Dimensional tolerance is related to, but different from fit in mechanical engineering, tolerances are assigned to parts for manufacturing purposes, as boundaries for acceptable build. No machine can hold dimensions precisely to the value, so there must be acceptable degrees of variation. If a part is manufactured, but has dimensions that are out of tolerance, tolerances can be applied to any dimension. The commonly used terms are, Basic size, the diameter of the shaft
38.
Milling (machining)
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Pocket milling has been regarded as one of the most widely used operations in machining. It is extensively used in aerospace and shipyard industries, in pocket milling the material inside an arbitrarily closed boundary on a flat surface of a work piece is removed to a fixed depth. Generally flat bottom end mills are used for pocket milling, firstly roughing operation is done to remove the bulk of material and then the pocket is finished by a finish end mill. Most of the milling operations can be taken care of by 2.5 axis CNC milling. This type of control can machine up to 80% of all mechanical parts. Since the importance of pocket milling is very relevant, therefore effective pocketing approaches can result in reduction in machining time, NC pocket milling can be carried out mainly by two tool paths, viz. linear and non-linear. In this approach, the movement is unidirectional. Zig-zag and zig tool paths are the examples of linear tool path, in zig-zag milling, material is removed both in forward and backward paths. In this case, cutting is done both with and against the rotation of the spindle and this reduces the machining time but increases machine chatter and tool wear. In zig milling, the tool moves only in one direction, the tool has to be lifted and retracted after each cut, due to which machining time increases. However, in case of zig milling surface quality is better, in this approach, tool movement is multi-directional. One example of non-linear tool path is contour-parallel tool path, in this approach, the required pocket boundary is used to derive the tool path. In this case the cutter is always in contact with the work material, hence the idle time spent in positioning and retracting the tool is avoided. For large-scale material removal, contour-parallel tool path is used because it can be consistently used with up-cut or down-cut method during the entire process. There are three different approaches that fall into the category of contour-parallel tool path generation and they are, In pair-wise intersection approach, the boundary of the pocket is brought inwards in steps, The offset segments will intersect at concave corners. To obtain the required contour, these intersections are to be trimmed off, on the other hand, in case of convex corner, the offset segments are extended and thereby connected to make the contour. These operations viz. offsetting, trimming and extending are repeatedly done to cover the entire machining volume with sufficient layer of profiles, in voronoi diagram approach, the pocket boundary is segmented and vornoi diagram is constructed for the entire pocket boundary. These vornoi diagrams are used for generating the tool path for machining and this method is considered to be more efficient and robust
39.
Drilling
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Drilling is a cutting process that uses a drill bit to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multipoint, the bit is pressed against the workpiece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the workpiece, cutting off chips from the hole as it is drilled, in rock drilling, the hole is usually not made through a circular cutting motion, though the bit is usually rotated. Instead, the hole is made by hammering a drill bit into the hole with quickly repeated short movements. The hammering action can be performed from outside of the hole or within the hole, drills used for horizontal drilling are called drifter drills. In rare cases, specially-shaped bits are used to cut holes of non-circular cross-section, drilled holes are characterized by their sharp edge on the entrance side and the presence of burrs on the exit side. Also, the inside of the hole usually has helical feed marks and this causes the workpiece to become more susceptible to corrosion and crack propagation at the stressed surface. A finish operation may be done to avoid these detrimental conditions, for fluted drill bits, any chips are removed via the flutes. Chips may form long spirals or small flakes, depending on the material, the type of chips formed can be an indicator of the machinability of the material, with long chips suggesting poor material machinability. When possible drilled holes should be located perpendicular to the workpiece surface and this minimizes the drill bits tendency to walk, that is, to be deflected from the intended center-line of the bore, causing the hole to be misplaced. The higher the ratio of the drill bit, the greater the tendency to walk. Constraining the position of the drill bit using a jig with drill bushings Surface finish produced by drilling may range from 32 to 500 microinches. Finish cuts will generate surfaces near 32 microinches, and roughing will be near 500 microinches, cutting fluid is commonly used to cool the drill bit, increase tool life, increase speeds and feeds, increase the surface finish, and aid in ejecting chips. Application of these fluids is usually done by flooding the workpiece with coolant and lubricant or by applying a spray mist, in deciding which drill to use it is important to consider the task at hand and evaluate which drill would best accomplish the task. There are a variety of styles that each serve a different purpose. The subland drill is capable of drilling more than one diameter, the spade drill is used to drill larger hole sizes. The indexable drill is useful in managing chips, the purpose of spot drilling is to drill a hole that will act as a guide for drilling the final hole. The hole is only drilled part way into the workpiece because it is used to guide the beginning of the next drilling process
40.
Turning
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Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates. The tools axes of movement may be literally a straight line, or they may be along some set of curves or angles, but they are essentially linear. Usually the term turning is reserved for the generation of external surfaces by this cutting action, thus the phrase turning and boring categorizes the larger family of processes. The cutting of faces on the workpiece, whether with a turning or boring tool, is called facing, Turning can be done manually, in a traditional form of lathe, which frequently requires continuous supervision by the operator, or by using an automated lathe which does not. Today the most common type of automation is computer numerical control. When turning, a piece of rigid material is rotated. Turning can be either on the outside of the cylinder or on the inside to produce tubular components to various geometries and those types of turning processes can produce various shapes of materials such as straight, conical, curved, or grooved workpiece. In general, turning uses simple single-point cutting tools, each group of workpiece materials has an optimum set of tools angles which have been developed through the years. The bits of metal from turning operations are known as chips. In some areas they may be known as turnings, Turning specific operations include, Turning This operation is one of the most basic machining processes. That is, the part is rotated while a single point cutting tool is moved parallel to the axis of rotation, Turning can be done on the external surface of the part as well as internally. The starting material is generally a workpiece generated by processes such as casting, forging, extrusion. Tapered turning a) from the compound slide b) from taper turning attachment c) using a hydraulic copy attachment d) using a C. N. C, Lathe e) using a form tool f) by the offsetting of the tailstock - this method more suited for shallow tapers. Spherical generation The proper expression for making or turning a shape is to generate as in to generate a form around an axis of revolution. A) using hydraulic copy attachment b) C. N. C, Lathe c) using a form tool d) using bed jig. Hard turning Hard turning is a turning done on materials with a Rockwell C hardness greater than 45 and it is typically performed after the workpiece is heat treated. The process is intended to replace or limit traditional grinding operations, Hard turning, when applied for purely stock removal purposes, competes favorably with rough grinding. However, when it is applied for finishing where form and dimension are critical, grinding produces higher dimensional accuracy of roundness and cylindricity
41.
Grinding (abrasive cutting)
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Grinding is an abrasive machining process that uses a grinding wheel as the cutting tool. It can produce very fine finishes and very accurate dimensions, yet in mass production contexts it can also rough out large volumes of metal quite rapidly. It is usually better suited to the machining of hard materials than is regular machining. Compared to regular machining, it is better suited to taking very shallow cuts. Grinding is a subset of cutting, as grinding is a true metal-cutting process, each grain of abrasive functions as a microscopic single-point cutting edge, and shears a tiny chip that is analogous to what would conventionally be called a cut chip. This is why the terms are used in separately in shop-floor practice. Lapping and sanding are subsets of grinding, selecting which of the following grinding operations to be used is determined by the size, shape, features and the desired production rate. Surface grinding uses an abrasive wheel to remove material, creating a flat surface. The tolerances that are achieved with grinding are ±2 × 10−4 inches for grinding a flat material. The surface grinder is composed of a wheel, a workholding device known as a chuck, either electromagnetic or vacuum. Grinding is commonly used on cast iron and various types of steel, materials that are less commonly ground are Aluminum, stainless steel, brass & plastics. These all tend to clog the cutting more than steel & cast iron. Cylindrical grinding is used to grind the cylindrical surfaces and shoulders of the workpiece, the workpiece is mounted on centers and rotated by a device known as a drive dog or center driver. The abrasive wheel and the workpiece are rotated by separate motors, the table can be adjusted to produce tapers. The wheel head can be swiveled, the five types of cylindrical grinding are, outside diameter grinding, inside diameter grinding, plunge grinding, creep feed grinding, and centerless grinding. A cylindrical grinder has a wheel, two centers that hold the workpiece, and a chuck, grinding dog, or other mechanism to drive the work. Most cylindrical grinding machines include a swivel to allow for the forming of tapered pieces, the wheel and workpiece move parallel to one another in both the radial and longitudinal directions. The abrasive wheel can have many shapes, standard disk-shaped wheels can be used to create a tapered or straight workpiece geometry while formed wheels are used to create a shaped workpiece
42.
Honing (metalworking)
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Honing is an abrasive machining process that produces a precision surface on a metal workpiece by scrubbing an abrasive stone against it along a controlled path. Honing is primarily used to improve the form of a surface. Typical applications are the finishing of cylinders for combustion engines, air bearing spindles. There are many types of hones but all consist of one or more stones that are held under pressure against the surface they are working on. In terms of sharpening knives, a honing steel does not actually hone knives, other similar processes are lapping and superfinishing. Honing uses a tool, called a honing stone or a hone. The hone is composed of grains that are bound together with an adhesive. Generally, honing grains are irregularly shaped and about 10 to 50 micrometers in diameter, smaller grain sizes produce a smoother surface on the workpiece. A honing stone is similar to a wheel in many ways. To counteract their friability, honing stones may be treated with wax or sulfur to improve life, any abrasive material may be used to create a honing stone, but the most commonly used are corundum, silicon carbide, cubic boron nitride, or diamond. The choice of material is usually driven by the characteristics of the workpiece material. In most cases, corundum or silicon carbide are acceptable, the hone is usually turned in the bore while being moved in and out. Special cutting fluids are used to give a smooth cutting action, machines can be portable, simple manual machines, or fully automatic with gauging depending on the application. Modern advances in abrasives have made it possible to much larger amount of material than was previously possible. This has displaced grinding in many applications where through machining is possible, external hones perform the same function on shafts. Since honing stones look similar to grinding wheels, it is tempting to think of honing as a form of low-stock removal grinding, instead, it is better to think of it as a self-truing grinding process. In grinding, the wheel follows a simple path, for example, in plunge grinding a shaft, the wheel moves in towards the axis of the part, grinds it, and then moves back out. Since each slice of the wheel repeatedly contacts the same slice of the workpiece, therefore, the accuracy of the finished workpiece geometry is limited to the accuracy of the truing dresser
43.
Key (engineering)
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In mechanical engineering, a key is a machine element used to connect a rotating machine element to a shaft. The key prevents relative rotation between the two parts and may enable torque transmission, for a key to function, the shaft and rotating machine element must have a keyway and a keyseat, which is a slot and pocket in which the key fits. The whole system is called a keyed joint, a keyed joint may allow relative axial movement between the parts. Commonly keyed components include gears, pulleys, couplings, and washers, there are five main types of keys, sunk, saddle, tangent, round, and spline. Types of sunk keys, rectangular, square, parallel sunk, gib-head, feather, parallel keys are the most widely used. They have a square or rectangular cross-section, square keys are used for smaller shafts and rectangular faced keys are used for shaft diameters over 6.5 in or when the wall thickness of the mating hub is an issue. Set screws often accompany parallel keys to lock the mating parts into place, the keyway is a longitudinal slot in both the shaft and mating part. Woodruff keys are semicircular, fitting partly into a circular segment keyway with the fitting into a longitudinal slot keyway in the mating part. The circular segment can be cut directly by cutting with a circular cutter without any reliefs. The main advantage of the Woodruff key is the elimination of milling near shaft shoulders, where stress concentrations, the latter is particularly important for high speed operation. The more exact fit of the key and keyway also reduces play, and stress concentrations in, common applications include machine tools, automotive applications, snowblowers and marine propellers. This type of key was developed by W. N. Woodruff of Connecticut, in 1888, he was awarded the John Scott Medal by the Franklin Institute for his invention. The tapered key is tapered only on the side that engages the hub, the keyway in the hub has a taper that matches that of the tapered key. Some taper keys have a gib, or tab, for easier removal during disassembly, the purpose of the taper is to secure the key itself, as well as, to firmly engage the shaft to the hub without the need for a set screw. The problem with taper keys is that they can cause the center of the rotation to be slightly off of the mating part. It is different from a shaft lock in that tapered keys have a matching taper on the keyway. A Scotch key or Dutch key also provides a not by milling but by drilling axially into the part. If the key is tapered, it is referred to as a Dutch pin and is driven in, a Hirth joint is similar to a spline joint but with the teeth on the butt of the shaft instead of on the surface
44.
Lapping
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Lapping is a machining process, in which two surfaces are rubbed together with an abrasive between them, by hand movement or using a machine. This produces microscopic conchoidal fractures as the abrasive rolls about between the two surfaces and removes material from both, the other form of lapping involves a softer material such as pitch or a ceramic for the lap, which is charged with the abrasive. The lap is then used to cut a harder material — the workpiece, the abrasive embeds within the softer material, which holds it and permits it to score across and cut the harder material. Taken to a limit, this will produce a polished surface such as with a polishing cloth on an automobile. This is one twentieth of the wavelength of light from the commonly used 632.8 nm helium neon laser light source, surfaces this flat can be molecularly bonded by bringing them together under the right conditions. By way of example, a piece of lead may be used as the lap, charged with emery, the small plate shown in the first picture is a hand lapping plate. That particular plate is made of cast iron, in use, a slurry of emery powder would be spread on the plate and the workpiece simply rubbed against the plate, usually in a figure-eight pattern. The second picture is of a commercially available lapping machine, the lap or lapping plate in this machine is 30 centimetres in diameter, about the smallest size available commercially. At the other end of the spectrum, machines with 8-to-10-foot-diameter plates are not uncommon. Referring to the picture again, the lap is the large circular disk on the top of the machine. On top of the lap are two rings, the workpiece would be placed inside one of these rings. A weight would then be placed on top of the workpiece, the weights can also be seen in the picture along with two fiber spacer disks that are used to even the load. In operation, the stay in one location as the lapping plate rotates beneath them. In this machine, a slurry pump can be seen at the side. When there is a requirement to lap very small specimens, a jig can be used to hold the material while it is lapped. A jig allows precise control of the orientation of the specimen to the lapping plate, due to the dimensions of such small samples, traditional loads and weights are too heavy as they would destroy delicate materials. The jig sits in a cradle on top of the lapping plate, where the mating of the two surfaces is more important than the flatness, the two pieces can be lapped together. This yields closeness-of-fit results comparable to that of two pieces, without quite the same degree of testing required for the latter
45.
Parallels (engineering)
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Parallels are rectangular blocks of metal, commonly made from tool steel, stainless steel or cast iron, which have 2,4 or 6 faces ground or lapped to a precise surface finish. Parallels come in pairs of two, which are machined to be the same dimensions their corresponding faces and they come in a variety of thicknesses and size, allowing them to be stacked up or to support a workpiece which doesnt have a flat profile. Generally, workshop parallels have 4 faces that are machined and ground - the front, back and sides, although some do have the ends with a smooth surface. The surface of a parallel can often tell how it was manufactured, with a showing that it was ground -. Parallels that only have 2 or 4 precision faces will often have the tool-marks from the machining on the non-ground sides, then, the individual finishes are applied, from drilling to machining a chamfer along the edges to remove any burrs or sharpened edges. They may also be lapped to achieve a smooth surface. Parallels are manufactured to either imperial or metric dimensions, and are sold in a set. Parallels are used in machining operations, be it milling, drilling, turning or sometimes grinding, the most common use is to support work when it is in a vise or clamped to the machine bed. Parallels of different sizes can be used to support a workpiece that doesnt have a surface underneath. Parallels can also be used if the vise itself has a damaged face, other uses include giving a raised surface when using t-slot clamps and for comparison with a surface or machined face to check the flatness
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Calipers
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A caliper is a device used to measure the distance between two opposite sides of an object. A caliper can be as simple as a compass with inward or outward-facing points. The tips of the caliper are adjusted to fit across the points to be measured, the caliper is then removed and it is used in many fields such as mechanical engineering, metalworking, forestry, woodworking, science and medicine. A plurale tantum sense of the word calipers coexists in natural usage with the regular noun sense of caliper, also existing colloquially but not in formal usage is referring to a vernier caliper as a vernier or a pair of verniers. In imprecise colloquial usage, some extend this even to dial calipers. In machine-shop usage, the caliper is often used in contradistinction to micrometer. In this usage, caliper implies only the factor of the vernier or dial caliper. The earliest caliper has been found in the Greek Giglio wreck near the Italian coast, the ship find dates to the 6th century BC. The wooden piece already featured a fixed and a movable jaw, although rare finds, caliper remained in use by the Greeks and Romans. A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty, the caliper had an inscription stating that it was made on a gui-you day at new moon of the first month of the first year of the Shijian guo period. The calipers included a slot and pin and graduated in inches, the modern vernier caliper, reading to thousandths of an inch, was invented by American Joseph R. Brown in 1851. It was the first practical tool for exact measurements that could be sold at a price within the reach of ordinary machinists, the inside calipers are used to measure the internal size of an object. The upper caliper in the image requires manual adjustment prior to fitting, fine setting of this caliper type is performed by tapping the caliper legs lightly on a handy surface until they will almost pass over the object. A light push against the resistance of the pivot screw then spreads the legs to the correct dimension and provides the required. The lower caliper in the image has a screw that permits it to be carefully adjusted without removal of the tool from the workpiece. Outside calipers are used to measure the size of an object. The same observations and technique apply to this type of caliper, with some understanding of their limitations and usage, these instruments can provide a high degree of accuracy and repeatability. They are especially useful when measuring over very large distances, consider if the calipers are used to measure a large diameter pipe, a vernier caliper does not have the depth capacity to straddle this large diameter while at the same time reach the outermost points of the pipes diameter
