1. MANUFACTURING PROCESSES
C H A P T E R N I N E

2. OBJECTIVES 1. 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.

3. UNDERSTANDING MANUFACTURING
Manufacturing is generally a complex activity involving a wide variety of resources and activities such as:
• Product design
• Purchasing
• Marketing
• Machinery and tooling
• Manufacturing
• Sales
• Process planning
• Production control
• Shipping
• Materials
• Support services
• Customer service

4. The Design Process and Concurrent Engineering
Sharing product design data among multiple users
concurrently can shorten the time to product realization
and result in a better product.
Design and manufacturing activities have traditionally taken place sequentially rather than concurrently or simultaneously.

5. COMPUTER-AIDED DESIGN AND PRODUCT DEVELOPMENT
Computer-aided design (CAD) allows the designer to conceptualize objects
more easily without having to make costly illustrations, models, or prototypes.
These systems are now capable of rapidly and completely analyzing designs, from a simple bracket to complex structures.
(Ford Motor Company/Dorling Kindersley.)

6. Computer-Aided Engineering Allows for Future Modification
Computer-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.)

7. Computer-Aided Engineering Links All Phases of Manufacturing
Computer-aided manufacturing (CAM) involves all phases of manufacturing by
utilizing and processing further the large amount of information on materials and
processes collected and stored in the organization’s database. Computers now assist
manufacturing engineers and others in organizing tasks such as programming
numerical control of machines; programming robots for materials handling and
assembly; designing tools, dies, and fixtures; and maintaining quality control.
Car Frames Being Welded
on a Robotic Assembly Line. (Courtesy of Adam Lubroth / Stone/Getty Images Inc.)

8. RAPID PROTOTYPING
Rapid prototyping systems allow the engineer to develop a prototype directly from a CAD design within minutes or
hours instead of the days or weeks it might otherwise take to create a prototype part.
(Courtesy of Stratasys, Inc.)
SLA Rapid Prototyping System. (Courtesy of 3D Systems
Corporation.)

9. RAPID PROTOTYPING Translating the Model
Today’s major rapid prototyping systems all work on a similar principle: they slice
the CAD model into thin layers, then create the model, layer by layer, from a material
that 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 CAD
Model Exported for Protoyping
(Lockhart, D.; Johnson, Cindy M.,
Engineering Design Communication:
Conveying Design Through Graphics,
1st, © Printed and
electronically reproduced by
permission of Pearson Education,
Inc., Upper Saddle River, New
Jersey.)

10. TYPES OF RAPID PROTOTYPING SYSTEMS
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.)

11. DESIGN FOR MANUFACTURE, ASSEMBLY, DISASSEMBLY, AND SERVICE
This area is termed design for manufacture (DFM). DFM is a comprehensive
approach 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.)

12. MATERIAL SELECTION
The following are the general types of materials used in manufacturing today, either individually or in combination:
• 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.
Standard shapes are often used in materials testing to make it easier to compare results. (Courtesy of Clive Streeter © Dorling Kindersley.)

13. PROPERTIES OF MATERIALS
Manufacturing properties of materials determine whether they can be cast, formed, machined, welded, and heat treated with relative ease
General Manufacturing Characteristics of Various Alloys
Methods used to process materials to the desired shapes can adversely affect the product’s final properties, service life, and cost.

14. COST AND AVAILABILITY OF MATERIALS APPEARANCE, SERVICE 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 resources
and maintaining a clean and healthy environment.

15. MANUFACTURING PROCESSES
There is usually more than one way to manufacture a part from a given material.

16. Processing Methods
The 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.

17. DIMENSIONAL ACCURACY AND 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 has
very 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.

18. MEASURING DEVICES USED IN MANUFACTURING
Although the machinist uses various
measuring devices depending on the kind
of 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.

19. OPERATIONAL AND MANUFACTURING COSTS
The design and cost of tooling, the lead time required to begin production, and
the 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.
quantity of parts
scrap rate
Availability of machines and equipment
safety

20. COMPUTER-INTEGRATED MANUFACTURING
Few developments in the history of manufacturing have had a more significant impact than computers.
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)

21. MANUFACTURING METHODS AND 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. The
principal methods of metal forming are:
• Casting
• Machining from standard stock
• Welding
• Forming from sheet stock
• Forging
Forged
Casted or Forged

22. DIMENSIONING
C H A P T E R T E N

23. OBJECTIVES
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.

24. UNDERSTANDING DIMENSIONING
The increasing need for precision manufacturing and interchangeability
has shifted responsibility for size control to the design engineer or detail drafter.
Practices for dimensioning architectural
and structural drawings are similar
in many ways to those for dimensioning
manufactured parts, but some practices
differ.
Refer to the following standards:
• ANSI/ASME Y Dimensioning and Tolerancing
• ASME Y Digital Product definition Data Practices
• ASME B (R1999) Preferred Metric Limits and Fits
Automatically Generated Dimensions. Views and dimensions can be generated automatically from a solid model. (Courtesy of Robert Kincaid.)

25. Three Aspects of Good Dimensioning
Technique of dimensioning
Placement of dimensions
Choice of dimensions

26. UNLESS OTHERWISE NOTED.
Tolerance
Tolerance is the total amount that the feature on the actual part is allowed
to vary from what is specified by the drawing or model dimension.
ALL TOLERANCES ±.02 INCH
UNLESS OTHERWISE NOTED. E X A M P L S
A Title Block Specifying Tolerances. (Courtesy of Dynojet Research, Inc.)

27. Geometric 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.

28. LINES USED IN DIMENSIONING
Dimension, Extension and Centerlines

29. ARROWHEADS
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.

30. LEADERS
A 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 possible
Don’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

31. DRAWING SCALE AND DIMENSIONING
Drawing scale is noted in the title block. The drawing should not be scaled for dimensions. (Courtesy of Dynojet Research, Inc.)
Many standard title blocks include a note such as:
DO NOT SCALE DRAWING
FOR DIMENSIONS

32. DIRECTION OF DIMENSION VALUES 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.

33. DIMENSION UNITS
A 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.)

34. MILLIMETER 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.

35. DECIMAL-INCH VALUES
Two-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.

36. RULES FOR DIMENSION VALUES
Good 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.

37. DUAL DIMENSIONING and COMBINATION UNITS
Dual dimensioning is used to show metric and decimal-inch dimensions on the same drawing. Two methods of displaying the dual dimensions are:
Position Method
Bracket Method
DIMENSIONS IN () ARE MILLIMETERS

38. Form and Proportion of Dimensioning Symbols.
DIMENSION SYMBOLS
Dimensioning 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.)

39. PLACING AND SHOWING 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)

40. SUPERFLUOUS DIMENSIONS
All necessary dimensions must be shown, but do not give unnecessary or superfluous dimensions.