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Job Shop
Job shops are typically small manufacturing systems that handle job production, that is, custom/bespoke or semi-custom/bespoke manufacturing processes such as small to medium-size customer orders or batch jobs. Job shops typically move on to different jobs (possibly with different customers) when each job is completed. Job shops machines are aggregated in shops by the nature of skills and technological processes involved, each shop therefore may contain different machines, which gives this production system processing flexibility, since jobs are not necessarily constrained to a single machine. In computer science the problem of job shop scheduling is considered strongly NP-hard. A typical example would be a machine shop, which may make parts for local industrial machinery, farm machinery and implements, boats and ships, or even batches of specialized components for the aircraft industry. Other types of common job shops are grinding, honing, jig-boring, gear manufacturing, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skills
A skill is the learned ability to act with determined results with good execution often within a given amount of time, energy, or both. Skills can often be divided into domain-general and domain-specific skills. For example, in the domain of work, some general skills would include time management, teamwork and leadership, self-motivation and others, whereas domain-specific skills would be used only for a certain job. Skill usually requires certain environmental stimuli and situations to assess the level of skill being shown and used. A skill may be called an art when it represents a body of knowledge or branch of learning, as in ''the art of medicine'' or ''the art of war''. Although the arts are also skills, there are many skills that form an art but have no connection to the fine arts. People need a broad range of skills to contribute to the modern economy. A joint ASTD and U.S. Department of Labor study showed that through technology, the workplace is changing, and ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process Engineering
Process engineering is the understanding and application of the fundamental principles and laws of nature that allow humans to transform raw material and energy into products that are useful to society, at an industrial level. By taking advantage of the driving forces of nature such as pressure, temperature and concentration gradients, as well as the law of conservation of mass, process engineers can develop methods to synthesize and purify large quantities of desired chemical products. Process engineering focuses on the design, operation, control, optimization and intensification of chemical, physical, and biological processes. Process engineering encompasses a vast range of industries, such as agriculture, automotive, biotechnical, chemical, food, material development, mining, nuclear, petrochemical, pharmaceutical, and software development. The application of systematic computer-based methods to process engineering is "process systems engineering". Overview Process engine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Job-shop Problem
Job-shop scheduling, the job-shop problem (JSP) or job-shop scheduling problem (JSSP) is an optimization problem in computer science and operations research. It is a variant of optimal job scheduling. In a general job scheduling problem, we are given ''n'' jobs ''J''1, ''J''2, ..., ''Jn'' of varying processing times, which need to be scheduled on ''m'' machines with varying processing power, while trying to minimize the makespan – the total length of the schedule (that is, when all the jobs have finished processing). In the specific variant known as ''job-shop scheduling'', each job consists of a set of ''operations'' ''O''1, ''O''2, ..., ''On'' which need to be processed in a specific order (known as ''precedence constraints''). Each operation has a ''specific machine'' that it needs to be processed on and only one operation in a job can be processed at a given time. A common relaxation is the flexible job shop, where each operation can be processed on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NP-hard
In computational complexity theory, NP-hardness ( non-deterministic polynomial-time hardness) is the defining property of a class of problems that are informally "at least as hard as the hardest problems in NP". A simple example of an NP-hard problem is the subset sum problem. A more precise specification is: a problem ''H'' is NP-hard when every problem ''L'' in NP can be reduced in polynomial time to ''H''; that is, assuming a solution for ''H'' takes 1 unit time, ''H''s solution can be used to solve ''L'' in polynomial time. As a consequence, finding a polynomial time algorithm to solve any NP-hard problem would give polynomial time algorithms for all the problems in NP. As it is suspected that P≠NP, it is unlikely that such an algorithm exists. It is suspected that there are no polynomial-time algorithms for NP-hard problems, but that has not been proven. Moreover, the class P, in which all problems can be solved in polynomial time, is contained in the NP class. De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Job Shop Ordonnancement
Work or labor (or labour in British English) is intentional activity people perform to support the needs and wants of themselves, others, or a wider community. In the context of economics, work can be viewed as the human activity that contributes (along with other factors of production) towards the goods and services within an economy. Work is fundamental to all societies, but can vary widely within and between them, from gathering in natural resources by hand, to operating complex technologies that substitute for physical or even mental effort by many human beings. All but the simplest tasks also require specific skills, equipment or tools, and other resources (such as material for manufacturing goods). Cultures and individuals across history have expressed a wide range of attitudes towards work. Outside of any specific process or industry, humanity has developed a variety of institutions for situating work in society. Besides objective differences, one culture may or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Machine Shop
A machine shop or engineering workshop (UK) is a room, building, or company where machining, a form of subtractive manufacturing, is done. In a machine shop, machinists use machine tools and cutting tools to make parts, usually of metal or plastic (but sometimes of other materials such as glass or wood). A machine shop can be a small business (such as a job shop) or a portion of a factory, whether a toolroom or a production area for manufacturing. The building construction and the layout of the place and equipment vary, and are specific to the shop; for instance, the flooring in one shop may be concrete, or even compacted dirt, and another shop may have asphalt floors. A shop may be air-conditioned or not; but in other shops it may be necessary to maintain a controlled climate. Each shop has its own tools and machinery which differ from other shops in quantity, capability and focus of expertise. The parts produced can be the end product of the factory, to be sold to customer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grinding (abrasive Cutting)
Grinding is a type of abrasive machining process which uses a grinding wheel as cutting tool. A wide variety of machines are used for grinding, best classified as portable or stationary: * Portable power tools such as angle grinders, die grinders and cut-off saws * Stationary power tools such as bench grinders and cut-off saws * Stationary hydro- or hand-powered sharpening stones Milling practice is a large and diverse area of manufacturing and toolmaking. 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 very hard materials than is "regular" machining (that is, cutting larger chips with cutting tools such as tool bits or milling cutters), and until recent decades it was the only practical way to machine such materials as hardened steels. Compared to "regular" machining, it is usually better suited to taking very ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Honing (metalworking)
Honing is an abrasive machining process that produces a precision surface on a metal workpiece by scrubbing an abrasive grinding stone or grinding wheel against it along a controlled path. Honing is primarily used to improve the geometric form of a surface, but can also improve the surface finish. Typical applications are the finishing of cylinders for internal combustion engines, air bearing spindles and gears. There are many types of hones, but all consist of one or more abrasive stones that are held under pressure against the surface they are working on. Other similar processes are lapping and superfinishing. Honing stones Honing uses a special tool, called a ''honing stone'' or a ''hone'', to achieve a precision surface. The hone is composed of abrasive grains that are bound together with an adhesive. Generally, honing grains are irregularly shaped and about 10 to 50 micrometers in diameter (300 to 1500 mesh grit). Smaller grain sizes produce a smoother surface o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jig Borer
The jig borer is a type of machine tool invented at the end of World War I to enable the quick and precise location of hole centers. It was invented independently in Switzerland and the United States. It resembles a specialized species of milling machine that provides tool and die makers with a higher degree of positioning precision (repeatability) and accuracy than those provided by general machines. Although capable of light milling, a jig borer is more suited to highly accurate drilling, boring, and reaming, where the quill or headstock does not see the significant side loading that it would with mill work. The result is a machine designed more for location accuracy than heavy material removal. A typical jig borer has a work table of around which can be moved using large handwheels (with micrometer-style readouts and verniers) on particularly carefully made shafts with a strong degree of gearing; this allows positions to be set on the two axes to an accuracy of . It is general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear Manufacturing
Gear manufacturing refers to the making of gears. Gears can be manufactured by a variety of processes, including casting, forging, extrusion, powder metallurgy, and blanking. As a general rule, however, machining is applied to achieve the final dimensions, shape and surface finish in the gear. The initial operations that produce a semifinishing part ready for gear machining as referred to as blanking operations; the starting product in gear machining is called a gear blank. Selection of materials The gear material should have the following properties: * High tensile strength to prevent failure against static loads * High endurance strength to withstand dynamic loads * Low coefficient of friction * Good manufacturability Gear manufacturing processes There are multiple ways in which gear blanks can be shaped through the cutting and finishing processes. Gear forming In gear form cutting, the cutting edge of the cutting tool has a shape identical with the shape of the space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fabrication (metal)
Metal fabrication is the creation of metal structures by cutting, bending and assembling processes. It is a value-added process involving the creation of machines, parts, and structures from various raw materials. Typically, a fabrication shop bids on a job, usually based on engineering drawings, and if awarded the contract, builds the product. Large fab shops employ a multitude of value-added processes, including welding, cutting, forming and machining. As with other manufacturing processes, both human labor and automation are commonly used. A fabricated product may be called a ''fabrication'', and shops specializing in this type of work are called ''fab shops''. The end products of other common types of metalworking, such as machining, metal stamping, forging, and casting, may be similar in shape and function, but those processes are not classified as fabrication. Processes *''Cutting'' is done by sawing, shearing, or chiselling (all with manual and powered variants) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continuous-flow Manufacturing
Continuous-flow manufacturing, or repetitive-flow manufacturing, is an approach to discrete manufacturing that contrasts with batch production. It is associated with a just-in-time and kanban production approach, and calls for an ongoing examination and improvement efforts which ultimately requires integration of all elements of the production system. The goal is an optimally balanced production line with little waste, the lowest possible cost, on-time and defect-free production. This strategy is typically applied in discrete manufacturing as an attempt to handle production volumes comprising discrete units of product in a flow which is more naturally found in process manufacturing. The basic fact is that in most cases, discrete units of a solid product cannot be handled in the same way as continuous quantities of liquid, gas or powder. Discrete manufacturing is more likely to be performed in batches of product units that are routed from process to process in the factory. Ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
