manufacturing engineering and technology assiut univ.-mech. eng. dept lecture-1 definition of...

Manufacturing Engineering and Technology Assiut Univ.-Mech. Eng. dept Lecture-1

Definition of "Manufacturing"

• "Manufacturing" is a process for converting ideas and market or customer needs into artifacts; Includes design, procurement, test, finance, human resources, marketing, etc.

• manufacturing is the conversion of raw materials into useful products

– Main Focus of This Course


Little "m" manufacturing is all about

• Creating shapes by various means and assembling these shapes into a useful product

• The processes used to transform raw material into finished products

• A physical product always has a shape– Function– Aesthetics

• These shapes are created by a wide variety of processes

• Students must remember that these processes exist only in the context of the larger Manufacturing process


Manufacturing

Cu

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People, money, machines and automation

Societal pressures, Government regulations, company plans and policies, etc

manufacturingRaw

material

Products


MaterialTransformation

ProcessesRa

w

Ma

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Pro

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Machines and Automation

Materials Science, Statics, Dynamics, Thermodynamics, Fluid dynamics

The manufacturing Process


TABLE 1.2 Shapes and Some Common Methods of Production

Shapes and Production MethodShape or feature Production method Flat surfaces Rolling, planing, broaching, milling, shaping, grinding Parts with cavities End milling, electrical-discharge machining, electrochemical machining,

ultrasonic machining, casting Parts with sharp features Permanent-mold casting, machining, grinding, fabricating, powder

metallurgy Thin hollow shapes Slush casting, electroforming, fabricating Tubular shapes Extrusion, drawing, roll forming, spinning, centrifugal casting Tubular parts Rubber forming, expanding with hydraulic pressure, explosive forming,

spinning Curvature on thin sheets Stretch forming, peen forming, fabricating, assembly Openings in thin sheets Blanking, chemical blanking, photochemical blanking Cross-sections Drawing, extrusion, shaving, turning, centerless grinding Square edges Fine blanking, machining, shaving, belt grinding Small holes Laser, electrical-discharge machining, electrochemical machining Surface textures Knurling, wire brushing, grinding, belt grinding, shot blasting, etching,

deposition, laser texturing Detailed surface features Coining, investment casting, permanent-mold casting, machining Threaded parts Thread cutting, thread rolling, thread grinding, chasing Very large parts Casting, forging, fabricating, assembly Very small parts Investment casting, machining, etching, powder metallurgy,

nanofabrication, LIGA, micromachining


FIGURE 1.4 An outline of engineering materials

Engineering Materials


FIGURE 1.6 Various methods of making a simple part: (a) casting or powder metallurgy, (b) forging or upsetting, (c) extrusion, (d) machining, (e) joining two pieces.

Production Methods for a Simple Part


Fundamentals of manufacturing - Manufacturing Concepts

• The method chosen depends on the material and the shape and properties required

• Formability• Machinability• Hardenability

• Castability• Compactability• Sinterability• Weldability


Why is Manufacturing Important?• Impact on economy

– Major wealth creation engines – Gross Domestic Product – jobs

• Most decisions made during design are impacted by production/manufacturing processes

• Critical Decisions/Trade-offs – function vs cost vs schedule

• Choose materials • Choose process(es)

– Cost determined by the material and the processes used to create the shape


Some functional parameters affected by production processes

• Mechanical properties (Strength, Hardness, Fatique, Ductility, Resistance to environment)

• Tolerances• Surface finish• Resistance to corrosion and abrasion• Electrical properties• Thermal Properties• Appearance/surface finish


Commercially Available Materials

TABLE 40.1Material Available asAluminumCopper and brassMagnesiumSteels and stainless steelsPrecious metalsZincPlasticsElastomersCeramics (alumina)GlassGraphite

P, F, B, T, W, S, IP, f, B, T, W, s, IP, B, T, w, S, IP, B, T, W, S, IP, F, B, t, W, IP, F, D, W, IP, f, B, T, wP, b, Tp, B, T, sP, B, T, W, sP, B, T, W, s

Note: P, plate or sheet; F, foil; B, bar; T, tubing; W, wire; S,structural shapes; I, ingots for casting. Lowercase letter indicates limited availability. Most of these materials are alsoavailable in powder form.


Manufacturing Process Capabilities

Figure 40.3 Manufacturing process capabilities for minimum part dimensions. Source: J. A. Schey, Introduction to Manufacturing Processes (2d ed.). McGraw-Hill, 1987.


Dimensional Tolerance

Figure 40.4 Dimensional tolerance capabilities of various manufacturing processes.


Dimensional Tolerance and Surface Finish

Figure 40.5 Relationship between relative manufacturing cost and dimensional tolerance.

Figure 40.6 Relative production time, as a function of surface finish produced by various manufacturing processes. Source: American Machinist. See also Fig. 25.33.


Examples of General Function/Process Relationships

• Cast metals tend to be brittle• Forging adds strength along flow lines• Machining is cost effective for small lot sizes• Casting, forging and extrusion have high

setup costs but low production costs• Heat treatments affect hardness, strength,

corrosion resistance and fatigue properties• Machining results in lots of scrap (the buy to

fly ratio)


Buy to Fly RatioThe weight of the purchased raw material

divided by the weight of the final part

Process Buy to fly ratio

Machining 1.1 - 50Hot closed die forging 1.2-1.5Sheet metal forming 1.1-1.25Extrusion 1.1-1.3Permanent mold casting 1.0-1.2Powder metallurgy 1.0-1.05


Critical Fact

• You cannot design any hardware without taking into account the production process used to make that product

• Manufacturing considerations must be included in the design as early as possible


What is Manufacturing - Dimensions

• Product Creative Characteristics (How new products differ from previous ones)

• Product Size (physical dimension)• Product Complexity/Sophistication• Scale• Material Flow• Degree of Automation• Organization


Product Creative Characteristics

• How new products differ from previous ones– Selection design (Lego houses)– Configuration design (automobiles)– Parametric design (portable generators)– Redesign (New VCR)– Original design (the original VCR, the Space

Shuttle)


Product Size (physical dimension)• A individual device on a computer chip• A computer chip • A television• An automobile• A Navy cruiser


Number of parts/amount of electronics/intelligence

• A nail• A TV• A car or truck• A 777 aircraft• A satellite• Mars sojourner• A CPU chip (5 million

components)


Scale

• Number of people and disciplines involved– Artisan– Garage machine shop– General Motors, Arlington Plant– Boeing Commercial Aircraft– Engineering firms who make bridges, chemical

plants or dams


Material Flow

• How the work is organized on the shop floor– Discrete parts (traditional job shop)– Cellular (New machine shops)– Semicontinuous – Continuous flow (bottle making)– Process (chemical industry and oil refineries)


Degree of Automation

• How much automation exists on the shop floor– Manual– Machine assisted– Computer controlled - islands of automation– Computer integrated manufacturing


Company Organization

• How the enterprises organize to produce– Traditional– Lean– Agile– Next Generation

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