TOPIC 12. MANUFACTURING

Text 1

 

1.Обратите внимание на перевод следующих слов и словосочетаний:

Sumerians - Шумеры (название ранней цивилизации);

Lascaux - Ласко (палеолитическая пещера близ г. Монтиньяк, на Ю. Франции);

cuneiform script -     шрифт клинописи;

incision - насечка;

lathe - станок;

screw thread - резьба;

batch - партия.

 

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A BRIEF HISTORY OF MANUFACTURING

Manufacturing dates back to the period 5000-4000 B.C., and thus, it is older than recorded history, the earliest forms of which were invented by the Sumerians around 3500 B.C. Primitive cave drawings, as well as markings on clay tablets and stone, needed some form of a brush and some sort of “paint,” as in the prehistoric cave paintings in Lascaux, France, estimated to be 16,000 years old; some means of scratching the clay tablets and baking them, as in cuneiform scripts and pictograms of 3000 B.C.; and simple tools for making incisions and carvings on the surfaces of stone, as in the hieroglyphs in ancient Egypt.

The manufacture of items for specific uses began with the production of various household artifacts, which were typically made of either wood, stone, or metal. The materials first used in making utensils and ornamental objects included gold, copper, and iron, followed by silver, lead, tin, bronze (an alloy of copper and tin), and brass (an alloy of copper and zinc). The processing methods first employed involved mostly casting and hammering, because they were relatively easy to perform. Over the centuries, these simple processes gradually began to be developed into more and more complex operations, at increasing rates of production and higher levels of product quality. Note, for example, that lathes for cutting screw threads already were available during the period from 1600 to 1700, but it was not until some three centuries later that automatic screw machines were developed.

 Although ironmaking began in the Middle East in about 1100 B.C., a major milestone was the production of steel in Asia during the period 600-800 A.D. A wide variety of materials continually began to be developed. Today, countless metallic and nonmetallic materials with unique properties are available, including engineered materials and various advanced materials. Among the available materials are industrial or high-tech ceramics, reinforced plastics, composite materials, and nanomaterials that are now used in an extensive variety of products, ranging from prosthetic devices and computers to supersonic aircraft.

Until the Industrial Revolution, which began in England in the 1750s and is also called the First Industrial Revolution, goods had been produced in batches and required much reliance on manual labor in all phases of their production. The Second Industrial Revolution is regarded by some as having begun in the mid-1900s with the development of solid-state electronic devices and computers.

Mechanization began in England and other countries of Europe, basically with the development of textile machinery and machine tools for cutting metal. This technology soon moved to the United States, where it continued to be further developed.

 A major advance in manufacturing occurred in the early 1800s with the design,

production, and use of interchangeable parts, conceived by the American manufacturer and inventor Eli Whitney (1765-1825). Prior to the introduction of interchangeable parts, much hand fitting was necessary because no two parts could be made exactly alike. By contrast, it is now taken for granted that a broken bolt can easily be replaced with an identical one produced decades after the original. Further developments soon followed, resulting in countless consumer and industrial products that we now cannot imagine being without.

  

Text 2

 

1.Обратите внимание на перевод следующих слов и словосочетаний:

computer-aided engineering - компьютерное моделирование;

paperless design -    безбумажный проект;

 

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ROLE OF COMPUTERS IN PRODUCT DESIGN

 Typically, product design first requires the preparation of analytical and physical models of the product for the purposes of visualization and engineering analysis. Although the need for such models depends on product complexity, constructing and studying these models have become highly simplified through the use of computer-aided design (CAD) and computer-aided engineering (CAE) techniques.

  CAD systems are capable of rapid and complete analyses of designs, whether it be a simple shelf bracket or a shaft in large and complex structures. The Boeing 777 passenger airplane, for example, was designed completely by computers in a process known as paperless design, with 2000 workstations linked to eight design servers. Unlike previous mock-ups of aircraft, no prototypes or mock-ups were built and the 777 was constructed and assembled directly from the CAD/CAM software that had been developed.

 Through computer-aided engineering, the performance of structures subjected,

for example, to static or fluctuating loads or to temperature gradients also can be simulated, analyzed, and tested, rapidly and accurately. The information developed is stored and can be retrieved, displayed, printed, and transferred anytime and anywhere within a company’s organization. Design modifications can be made and optimized (as is often the practice in engineering, especially in the production of large structures) directly, easily, and at any time.

  Computer-aided manufacturing involves all phases of manufacturing, by utilizing

and processing the large amount of information on materials and processes gathered

and stored in the organization’s database. Computers greatly assist in organizing the information developed and performing such tasks as programming for numerical control machines and for robots for material-handling and assembly operations, designing tools, dies, molds, fixtures, and work-holding devices, and maintaining quality control.

 On the basis of the models developed and analyzed in detail, product designers then finalize the geometric features of each of the product’s components, including specifying their dimensional tolerances and surface-finish characteristics. Because all components, regardless of their size, eventually have to be assembled into the final product, dimensional tolerances are a major consideration in manufacturing. Indeed, dimensional tolerances are equally important for small products as well as for car bodies or airplanes. The models developed also allow the specification of the mechanical and physical properties required, which in turn affect the selection of materials.

 

Text 3

 

1.Обратите внимание на перевод следующих слов и словосочетаний:

prototype -     прототип;

casting - отливка;

forming - формовка;

machining - механическая обработка;

rapid-prototyping technique - технология быстрого прототипирования;

virtual prototyping - виртуальное прототипирование.

 

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PROTOTYPES

A prototype is a physical model of an individual component or product. The prototypes developed are carefully reviewed for possible modifications to the original design, materials, or production methods. An important and continuously evolving technology is rapid prototyping. Using CAD/CAM and various specialized technologies, designers can now make prototypes rapidly and at low cost, from metallic or nonmetallic materials such as plastics and ceramics.

 Prototyping new components by means of traditional methods (such as casting,

forming, and machining) could cost an automotive company hundreds of millions of dollars a year, with some components requiring a year or more to complete. Rapid prototyping can significantly reduce costs and the associated product-development times. Rapid-prototyping techniques are now advanced to such a level that they also can be used for low-volume (in batches typically of fewer than 100 parts) economical production of a variety of actual and functional parts to be assembled into products.

 Virtual prototyping is a software-based method that uses advanced graphics and virtual-reality environments to allow designers to view and examine a part in detail. This technology, also known as simulation-based design, uses CAD packages to render a part such that, in a 3-D interactive virtual environment, designers can observe and evaluate the part as it is being drawn and developed. Virtual prototyping has been gaining importance, especially because of the availability of low-cost computers and simulation and analysis tools.

Text 4

 

1.Обратите внимание на перевод следующих слов и словосочетаний:

green design - экологическое проектирование;

discard - отходы;

air fleet - воздушный флот;

slag -     выгар;

foundry - литьё;

hazardous waste -    опасные отходы;

lubricant - смазка;

coolant - охлаждающее вещество;

solvent - растворитель;

furnace - печь (техническая);

design for the environment - проектирование для окружающей среды (Программа, разработанная в 1992 г. Агентством по окружающей среды США, предназначенная для снижения общего антропогенного воздействия на окружающую среду и здоровье человека);

design for recycling - технология проектирования с учётом возможностей повторного использования или утилизации.

 

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GREEN DESIGN AND MANUFACTURING

 In the United States alone, 9 million passenger cars, 300 million tires, 670 million compact fluorescent lamps, and more than 5 billion kilograms of plastic products are discarded each year. Every three months, industries and consumers discard enough aluminum to rebuild the U.S. commercial air fleet. Note that, as indicated subsequently, the term discarding implies that the products have reached the end of their useful life; it does not necessarily mean that they are wasted and dumped into landfills.

  The particular manufacturing process and the operation of machinery can each have a significant environmental impact. Manufacturing operations generally produce some waste, such as:

a. Chips from machining and trimmed materials from sheet forming, casting, and molding operations.

b. Slag from foundries and welding operations.

c. Additives in sand used in sand-casting operations.

d. Hazardous waste and toxic materials used in various products.

e. Lubricants and coolants in metalworking and machining operations.

f. Liquids from processes such as heat treating and plating.

g. Solvents from cleaning operations.

h. Smoke and pollutants from furnaces and gases from burning fossil fuels.

   The adverse effects of these activities, their damage to our environment and to the Earth’s ecosystem, and, ultimately, their effect on the quality of human life are now widely recognized and appreciated. Major concerns involve global warming, greenhouse gases (carbon dioxide, methane, and nitrous oxide), acid rain, ozone depletion, hazardous wastes, water and air pollution, and contaminant seepage into water sources. One measure of the adverse impact of human activities is called the carbon footprint, which quantifies the amount of greenhouse gases produced in our daily activities.

The term green design and manufacturing is now in common usage in all industrial activities, with a major emphasis on design for the environment (DFE). Also called environmentally conscious design and manufacturing, this approach considers all possible adverse environmental impacts of materials, processes, operations, and products, so that they can all be taken into account at the earliest stages of design and production.

 These goals, which increasingly have become global, also have led to the concept of design for recycling (DFR). Recycling may involve one of two basic activities:

Biological cycle: Organic materials degrade naturally, and in the simplest version, they lead to new soil that can sustain life. Thus, product design involves the use of (usually) organic materials. The products function well for their intended life and can then be safely discarded.

Industrial cycle: The materials in the product are recycled and reused continuously. For example, aluminum beverage cans are recycled and reused after they have served their intended purpose. To demonstrate the economic benefits of this approach, it has been determined that producing aluminum from scrap, instead of from bauxite ore, reduces production costs by as much as 66% and reduces

energy consumption and pollution by more than 90%.

   One of the basic principles of design for recycling is the use of materials and product-design features that facilitate biological or industrial recycling. In the U.S. automotive industry, for example, about 75% of automotive parts (mostly metal) are now recycled, and there are continuing plans to recycle the rest as Well, including plastics, glass, rubber, and foam. About 100 million of the 300 million discarded automobile tires are reused in various ways.

 

Text 5

1.Обратите внимание на перевод следующих слов и словосочетаний:

materials engineer - инженер по материалам;

shape-memory alloy - сплав с эффектом запоминания формы.

 

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SELECTION OF MATERIALS

An increasingly wide variety of materials are now available, each type having its own material properties and manufacturing characteristics, advantages and limitations, material and production costs, and consumer and industrial applications. The selection of materials for products and their components is typically made in consultation with materials engineers, although design engineers may also be sufficiently experienced and qualified to do so. At the forefront of new materials usage are industries such as the aerospace and aircraft, automotive, military equipment, and sporting goods industries.

The general types of materials used, either individually or in combination with

other materials, are the following:

· Ferrous metals: carbon, alloy, stainless, and tool and die steels.

· Nonferrous metals: aluminum, magnesium, copper, nickel, titanium, superalloys, refractory metals, beryllium, zirconium, low-melting-point alloys, and precious metals.

· Plastics (polymers): thermoplastics, thermosets, and elastomers.

· Ceramics, glasses, glass ceramics, graphite, diamond, and diamond-like

materials.

· Composite materials: reinforced plastics and metal-matrix and ceramic-matrix

composites.

· Nanomaterials.

· Shape-memory alloys (also called smart materials), amorphous alloys, semiconductors, and superconductors.

 

Text 6

 

1.Обратите внимание на перевод следующих слов и словосочетаний:

extrusion - выдавливание (на прессе);

powder metallurgy - порошковая металлургия;

molding - литьё;

broaching - протягивание;

ultrasonic machining - ультразвуковая обработка (материалов);

ultraprecision - особо высокой точности;

honing - хонингование;

lapping - полирование, доводка;

polishing - полировка;

burnishing - сглаживание, шлифование;

deburring - удаление заусенцев;

coating - нанесение покрытия;

plating - нанесение гальванического покрытия;

microfabrication - микрообработка;

nanofabrication - нанопроизводство;

lithography - литография;

 

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SELECTION OF MANUFACTURING PROCESSES

  As will be described throughout this text, there is often more than one method that can be employed to produce a component for a product from a given material The following broad categories of manufacturing methods are all applicable to metallic as well as nonmetallic materials:

a. Casting

b. Forming and shaping: rolling, forging, extrusion, drawing, sheet forming, powder metallurgy, and molding.

c. Machining: turning, boring, drilling, milling, planing, shaping, broaching; grinding; ultrasonic machining; chemical, electrical, and electrochemical machining; and high-energy-beam machining. This broad category also includes micromachining for producing ultraprecision parts.

d. Joining: welding, brazing, soldering, diffusion bonding, adhesive bonding, and mechanical joining.

e. Finishing: honing, lapping, polishing, burnishing, deburring, surface treating,

coating, and plating.

f. Microfabrication and nanofabrication: technologies that are capable of producing parts with dimensions at the micro (one-millionth of a meter) and

nano (one-billionth of a meter) levels; fabrication of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS), typically involving processes such as lithography, surface and bulk micromachining, etching, LIGA, and various specialized processes.

The selection of a particular manufacturing process or, more often, sequence of processes, depends on the geometric features of the parts to be produced, including the dimensional tolerances and surface texture required, and on numerous factors pertaining to the particular workpiece material and its manufacturing properties. To emphasize the challenges involved, consider the following two cases:

a. Brittle and hard materials cannot be shaped or formed without the risk of fracture, unless they are performed at elevated temperatures, whereas these materials can easily be cast, machined, or ground.

b. Metals that have been preshaped at room temperature become less formable

during subsequent processing, which, in practice, is often required to complete the part; this is because the metals have become stronger, harder, and less ductile than they were prior to processing them further.