manufacturing processes c h a p t e r n i n e. technical drawing with engineering graphics, 14/e...

MANUFACTURINGMANUFACTURINGPROCESSESPROCESSES

C H A P T E R N I N E

Technical Drawing with Engineering Graphics, 14/eGiesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman

© 2012, 2009, 2003, Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.

OBJECTIVESOBJECTIVES1. Describe the role of computer-aided design in project development.

2. Define rapid prototyping and list four rapid prototyping technologies.

3. Describe the role of design in manufacture, assembly, disassembly, and service.

4. Define modeling for assembly.

5. Describe the role of material selection and material properties.

6. List the major manufacturing processes.

7. Look up accuracy and surface finishes for manufacturing processes.

8. Describe the role of measuring devices in production.

9. List factors that determine the cost of manufactured goods.

10.Define computer-integrated manufacturing.



UNDERSTANDING UNDERSTANDING MANUFACTURINGMANUFACTURING

Manufacturing is generally a complex activity involving a wide variety of resources and activities such as:

• • Product designProduct design• • PurchasingPurchasing• • MarketingMarketing• • Machinery and toolingMachinery and tooling• • ManufacturingManufacturing• • SalesSales• • Process planningProcess planning• • Production controlProduction control• • ShippingShipping• • MaterialsMaterials• • Support servicesSupport services• • Customer serviceCustomer service



THE DESIGN PROCESSTHE DESIGN PROCESSAND CONCURRENT AND CONCURRENT

ENGINEERINGENGINEERINGSharing product design data among multiple usersconcurrently can shorten the time to product realizationand result in a better product.

Design and manufacturing activities have traditionally taken place sequentially rather than concurrently or simultaneously.



COMPUTER-AIDED DESIGN AND COMPUTER-AIDED DESIGN AND PRODUCT DEVELOPMENTPRODUCT DEVELOPMENT

Computer-aided design Computer-aided design (CAD) (CAD) allowsallows the designer the designer to conceptualize objectsto conceptualize objectsmore easily without having more easily without having to make costly illustrations, to make costly illustrations, models, or prototypesmodels, or prototypes.

(Ford Motor Company/Dorling Kindersley.)

These systems are now capable of rapidly and completely analyzing designs, from a simple bracket to complex structures.



COMPUTER-AIDED ENGINEERING COMPUTER-AIDED ENGINEERING ALLOWS FORALLOWS FOR

FUTURE MODIFICATIONFUTURE MODIFICATIONComputer-aided engineering (CAE) allows the performance of structures subjected to static or fluctuating loads and various temperatures to be simulated, analyzed, and tested efficiently, accurately, and more quickly than ever. The information developed can be stored, retrieved, displayed, printed, and transferred anywhere in the organization.

Fiberglass Chassis for a Lotus Car Being Removed from the Mold. (Lotus Cars Ltd. /Dorling Kindersley.)



COMPUTER-AIDED ENGINEERING COMPUTER-AIDED ENGINEERING LINKS ALLLINKS ALL

PHASES OF MANUFACTURINGPHASES OF MANUFACTURINGComputer-aided manufacturing (CAM) involves all phases of manufacturing byutilizing and processing further the large amount of information on materials andprocesses collected and stored in the organization’s database. Computers now assistmanufacturing engineers and others in organizing tasks such as programmingnumerical control of machines; programming robots for materials handling andassembly; designing tools, dies, and fixtures; and maintaining quality control.

Car Frames Being Weldedon a Robotic Assembly Line. (Courtesy of Adam Lubroth / Stone/Getty Images Inc.)



RAPID PROTOTYPINGRAPID PROTOTYPING

SLA Rapid Prototyping System. (Courtesy of 3D SystemsCorporation.)

(Courtesy of Stratasys, Inc.)

Rapid prototyping systems allow the engineer to develop a prototype directly from a CAD design within minutes orhours instead of the days or weeks it might otherwise take to create a prototype part.



RAPID PROTOTYPINGRAPID PROTOTYPINGTRANSLATING THE MODELTRANSLATING THE MODEL

Today’s major rapid prototyping systems all work on a similar principle: they slicethe CAD model into thin layers, then create the model, layer by layer, from a materialthat can be fused to the next layer until the entire part is realized.

To send a CAD file to most rapid prototyping systems, often you export a file in the STL ( stereolithography) file format.

Faceted Surface on a CADModel Exported for Protoyping(Lockhart, D.; Johnson, Cindy M.,Engineering Design Communication:Conveying Design Through Graphics,1st, © 2000. Printed andelectronically reproduced bypermission of Pearson Education,Inc., Upper Saddle River, NewJersey.)



TYPES OF RAPID PROTOTYPING TYPES OF RAPID PROTOTYPING SYSTEMSSYSTEMS

• Stereolithography Apparatus (SLA)

• Solid Ground Curing (SGC)

• Selective Laser Sintering (SLS)

• Fused Deposition Modeling (FDM)

•Laminated Object Manufacturing (LOM)

• Topographic Shell Fabrication (TSF)

• 3D Printing

• Rapid Tooling

• Direct Shell Production Casting (DSPC)

3D Printer Model. (Courtesy of Z Corporation.)



DESIGN FOR MANUFACTURE, DESIGN FOR MANUFACTURE, ASSEMBLY, DISASSEMBLY,ASSEMBLY, DISASSEMBLY,

AND SERVICE AND SERVICE

This area is termed design for manufacture (DFM). DFM is a comprehensiveapproach to producing goods and integrating the design process with materials, manufacturing methods, process planning, assembly, testing, and quality assurance.

(Courtesy of the New York Times.)



MATERIAL SELECTIONMATERIAL SELECTION

Standard shapes are often used in materials testing to make it easier to compare results. (Courtesy of Clive Streeter © Dorling Kindersley.)

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

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

• Plastics: thermoplastics, thermosets, and elastomers.

• Ceramics: glass ceramics, glasses, graphite, diamond, and diamond-like materials.

• Composite materials: reinforced plastics, metal-matrix and ceramic-matrix composites. These are also known as engineered materials.

• Nanomaterials: shape-memory alloys, amorphous alloys, superconductors, and various other materials with unique properties.

The following are the general types of materials used in manufacturing today, either individually or in combination:



PROPERTIES OF MATERIALSPROPERTIES OF MATERIALS

General Manufacturing Characteristics of Various Alloys

Manufacturing properties of materials determine whether they can be cast, formed, machined, welded, and heat treated with relative ease

Methods used to process materials to the desired shapes can adversely affect the product’s final properties, service life, and cost.



COST AND AVAILABILITY OF COST AND AVAILABILITY OF MATERIALS APPEARANCE, MATERIALS APPEARANCE,

SERVICE LIFE, AND RECYCLINGSERVICE LIFE, AND RECYCLING

Cost and availability of raw and processed materials and manufactured components are major concerns in manufacturing. Competitively, the economic aspects of material selection are as important as the technological considerations of properties and characteristics of materials.

The appearance of materials after they have been manufactured into products influences their appeal to the consumer.

Time- and service-dependent phenomena such as wear, fatigue, creep, and dimensional stability are important.

Recycling or proper disposal of materials at the end of their useful service lives has become increasingly important in an age when we are more conscious of preserving resourcesand maintaining a clean and healthy environment.



MANUFACTURING PROCESSESMANUFACTURING PROCESSESThere is usually more than one way to manufacture a part from a given material.



PROCESSING METHODSPROCESSING METHODSThe broad categories of processing methods for materials are:

• Casting

• Forming and Shaping

• Machining

• Joining

• Finishing

Selecting a particular manufacturing process, or a series of processes, depends not only on the shape to be produced but also on many other factors pertaining to material properties.



DIMENSIONAL ACCURACYDIMENSIONAL ACCURACYAND SURFACE FINISHAND SURFACE FINISH

Ultraprecision manufacturing techniques and machinery are now being developed and are coming into more common use. For machining mirrorlike surfaces, for example, the cutting tool is a very sharp diamond tip, and the equipment hasvery high stiffness and must be operated in a room where the temperature is controlled within 1°C. Highly sophisticated techniques such as molecular-beam epitaxy and scanningtunneling microscopy are being implemented to obtain accuracies on the order of the atomic lattice 0.1 nm.



MEASURING DEVICES USEDMEASURING DEVICES USEDIN MANUFACTURINGIN MANUFACTURING

Although the machinist uses variousmeasuring devices depending on the kindof dimensions (fractional, decimal, or metric) shown on the drawing, to dimension correctly, the engineering designer must have a working knowledge of common measuring tools.

Most measuring devices in manufacturing are adjustable so they can be used for a range of measurements, but some measuring devices are designed to be used for only one particular dimension.



OPERATIONALOPERATIONALAND MANUFACTURING COSTSAND MANUFACTURING COSTS

The design and cost of tooling, the lead time required to begin production, andthe effect of workpiece material on tool and die life are major considerations.Depending on its size, shape, and expected life, the cost of tooling can be substantial. For example, a set of steel dies for stamping sheet metal fenders for automobiles may cost about $2 million.

scrap rate

quantity of parts

Availability of machines and equipmentsafety



COMPUTER-INTEGRATED COMPUTER-INTEGRATED MANUFACTURINGMANUFACTURING

Computer numerical control (CNC)

Adaptive control (AC)

Industrial robots

Automated handling of materials

Automated and robotic assembly

Computer-aided process planning (CAPP)

Group technology (GT)

Just-in-time (JIT)

Cellular manufacturing

Flexible manufacturing systems (FMS)

Expert systems

Artificial intelligence (AI)

Few developments in the history of manufacturing have had a more significant impact than computers.



MANUFACTURING METHODS MANUFACTURING METHODS AND THE DRAWINGAND THE DRAWING

In designing a part, consider what materials and manufacturing processes are to be used. These processes will determine the representation of the detailed features of the part, the choice of dimensions, and the machining or processing accuracy. Theprincipal methods of metal forming are:

• Casting• Machining from standard stock• Welding• Forming from sheet stock• Forging

ForgedForgedCasted or ForgedCasted or Forged

C H A P T E R T E NDIMENSIONINGDIMENSIONING



OBJECTIVESOBJECTIVES

1. Use conventional dimensioning techniques to describe size and shape accurately on an engineering drawing.

2. Create and read a drawing at a specified scale.

3. Correctly place dimension lines, extension lines, angles, and notes.

4. Dimension circles, arcs, and inclined surfaces.

5. Apply finish symbols and notes to a drawing.

6. Dimension contours.

7. Use standard practices for dimensioning prisms, cylinders, holes, and curves.

8. List practices for dimensioning a solid model as documentation.

9. Identify guidelines for the dos and don’ts of dimensioning.



UNDERSTANDING UNDERSTANDING DIMENSIONINGDIMENSIONING

The increasing need for precision manufacturing and interchangeabilityhas shifted responsibility for size control to the design engineer or detail drafter.

Practices for dimensioning architecturaland structural drawings are similarin many ways to those for dimensioningmanufactured parts, but some practicesdiffer.

Refer to the following standards:• ANSI/ASME Y14.5-2009 Dimensioning and Tolerancing• ASME Y14.41-2003 Digital Product definition Data Practices• ASME B4.2-1978 (R1999) Preferred Metric Limits and Fits

Automatically Generated Dimensions. Views and dimensions can be generated automatically from a solid model. (Courtesy of Robert Kincaid.)



THREE ASPECTS OF GOOD THREE ASPECTS OF GOOD DIMENSIONINGDIMENSIONING

Technique of dimensioning

Placement of dimensions

Choice of dimensions



TOLERANCETOLERANCETolerance is the total amount that the feature on the actual part is allowedto vary from what is specified by the drawing or model dimension.

A Title Block Specifying Tolerances. (Courtesy of Dynojet Research, Inc.)

ALL TOLERANCES ±.02 INCHUNLESS OTHERWISE NOTED.E

XAMPLES



GEOMETRIC BREAKDOWNGEOMETRIC BREAKDOWN

Engineering structures are composed largely of simple geometric shapes, such as the prism, cylinder, pyramid, cone, and sphere. They may be exterior (positive) or interior (negative) forms.



LINES USED IN DIMENSIONINGLINES USED IN DIMENSIONINGDimension, Extension and Centerlines



ARROWHEADSARROWHEADS

When you are drawing by hand and using the arrowhead method in which both strokes are directed toward the point, it is easier to make the strokes toward yourself.



LEADERSLEADERSA leader is a thin, solid line directing attention to a note or dimension and starting with an arrowhead or dot.

For the Best Appearance, Make Leaders• near each other and parallel• across as few lines as possibleDon’t Make Leaders• parallel to nearby lines of the drawing• through a corner of the view• across each other• longer than needed• horizontal or vertical



DRAWING SCALEDRAWING SCALEAND DIMENSIONINGAND DIMENSIONING

Many standard title blocks include a note such as:

DO NOT SCALE DRAWING FOR DIMENSIONS

Drawing scale is noted in the title block. The drawing should not be scaled for dimensions. (Courtesy of Dynojet Research, Inc.)



DIRECTION OF DIMENSIONDIRECTION OF DIMENSIONVALUES AND NOTESVALUES AND NOTES

All dimension values and notes are lettered horizontally to be read from the bottom of the sheet, as oriented by the title block.



DIMENSION UNITSDIMENSION UNITSA note stating ALL MEASUREMENTS IN MILLIMETERS or ALL MEASUREMENTS IN INCHES UNLESS OTHERWISE NOTED is used in the title block to indicate the measurement units…

(Courtesy of Dynojet Research, Inc.)



MILLIMETER VALUESMILLIMETER VALUES

The millimeter is the commonly used unit for most metric engineering drawings. One-place millimeter decimals are used when tolerance limits permit. Two (or more)–place millimeter decimals are used when higher tolerances are required.



DECIMAL-INCH VALUESDECIMAL-INCH VALUESTwo-place inch decimals are typical when tolerance limits permit. Three or more decimal places are used for tolerance limits in the thousandths of an inch. In two-place decimals, the second place preferably should be an even digit.



RULES FOR DIMENSION VALUESRULES FOR DIMENSION VALUESGood hand-lettering is important for dimension values on sketches. The shop produces according to the directions on the drawing so to save time and prevent costly mistakes, make all lettering perfectly legible.

Make all decimal points bold, allowing ample space. When the metric dimension is a whole number, do not show either a decimal point or a zero. When the metric dimension is less than 1 mm, a zero precedes the decimal point.

When the decimal-inch dimension is used on drawings, a zero is not used before the decimal point of values less than 1 in.



DUAL DIMENSIONING AND DUAL DIMENSIONING AND COMBINATION UNITSCOMBINATION UNITS

Dual dimensioning is used to show metric and decimal-inch dimensions on the same drawing. Two methods of displaying the dual dimensions are:

1. Position Method2. Bracket Method DIMENSIONS IN () ARE MILLIMETERS



DIMENSION SYMBOLSDIMENSION SYMBOLSDimensioning symbols are used to replace traditional terms or abbreviations.

Form and Proportion of Dimensioning Symbols. (Reprinted from ASME Y14.5M-1994 (R2004),by permission of The American Society of Mechanical Engineers. All rights

reserved.)



PLACING AND SHOWINGPLACING AND SHOWING DIMENSIONS LEGIBLY DIMENSIONS LEGIBLY

Rules for the placement of dimensions help you dimension your drawings so that they are clear and readable…

Fitting Dimension Values in Limited Spaces (Metric Dimensions)



SUPERFLUOUS DIMENSIONSSUPERFLUOUS DIMENSIONSAll necessary dimensions must be shown, but do not give unnecessary or superfluous dimensions.

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