2. Section 1 Introduction to Drafting
Chapter 3
Introduction to CAD
Section 1 Introduction to Drafting

3. Objectives Explain computer-aided drafting and design.
Identify common applications for CAD in different areas of drafting.
List the components of a typical CAD workstation.
Identify features of CAD software and how they should be evaluated when selecting a program.
Explain the advantages of specific CAD applications.
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4. What Is CAD? Tool used to plan and design parts.
Automates symbol creation and object duplication.
Incorporates hardware and software.
Requires knowledge of drafting principles and practices.
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5. Why Use CAD? Productivity Flexibility Uniformity Ease of scaling
(EdgeCAM/Pathtrace)
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6. CAD Productivity Benefits
Significant time and money savings over manual drafting.
Increased drawing quality.
Reduced number of revisions.
Symbol library applications.
Schedule generation and analysis tools.
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7. Symbol Library
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8. CAD Flexibility Benefits
Plotting at a variety of scales.
Presentation and media options.
Data sharing.
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9. CAD Uniformity Benefits
Accurate adherence to standards.
Consistent symbol generation.
Ensured line quality.
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10. CAD Scaling Benefits Objects typically drawn at full size.
Drawing plotted at specified scale.
Drafting time and potential for errors minimized.
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11. Mechanical CAD Applications
Automatic schedule generation.
Rendering capability.
Animation functions.
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12. Part Schedule Production
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13. CAD Workstation Used together with CAD software.
Often connected to other devices in network.
May be connected to mainframe.
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14. CAD Workstation (Cont.)
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15. Computer Components Central processing unit (CPU) Output device
Input device
Storage devices
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16. Storage Devices Used to save data for later use. Computer hard drive
CD-R drive
CD-RW drive
DVD drive
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17. Display Device Typically a CRT or LCD monitor.
Size defines screen area.
Video card should meet needs of application.
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18. Input Devices Keyboard Mouse Trackball Digitizer puck Light pens
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19. Output Devices Pen plotter Laser printer Inkjet printers
Inkjet plotters
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20. Pen Plotter Traditional device for CAD work.
Generates vector drawings.
Used for large-format output.
Produces very accurate line quality.
Disadvantage is slow operation.
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21. Inkjet Printers and Plotters
Generate raster drawings.
Used for high-quality color renderings.
Potential disadvantages are slow operation and cost.
(DesignJet Division, Hewlett-Packard)
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22. CAD Packages Types and costs vary based on features provided.
Lower-end systems used for 2D drawing.
More advanced software available for 3D work.
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23. Selecting a CAD Package
Consider product features and specific needs.
Ease of use
Hardware requirements
Product support
Warranty coverage
Specific tools in software
Cost
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24. Types of CAD Packages General purpose CAD packages
Advanced mechanical drafting and modeling CAD packages
AEC CAD packages
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25. General Purpose CAD Features
Functions for drawing objects
Automated dimensioning
Hatch pattern generation
Text functions and font types
Editing functions
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26. CAD Hatch Patterns
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27. General Purpose CAD Features
Layers
Object display colors
Linetype definitions
Coordinate entry methods
Methods for entering commands
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28. General Purpose CAD Features (Cont.)
Drawing unit formats
Display controls
Drawing aids
Printing or plotting functions
Customization options
Data exchange methods
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29. 3D Drawing Features Available in more advanced programs.
Shading and rendering
Animation
Mass property analysis
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30. Types of 3D Models Surface model Solid model
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31. Advanced Mechanical Drafting and Modeling CAD Packages
Designed for advanced engineering applications.
Provide additional 3D modeling features.
Commonly used in automated manufacturing.
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32. Advanced Mechanical Drafting and Modeling Features
Solid modeling tools
Parametric modeling tools
Automatic view generation
Mechanical symbol libraries
CAD/CAM functionality
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33. Solid Modeling Building from primitives. Revolving 2D profiles.
Extruding 2D profiles.
Removing material.
Sweep operations.
Loft operations.
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34. Extruded Solid Model
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35. Revolved Solid Model
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36. Swept Solid Model
(Anthony J. Panozzo)
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37. Parametric Modeling Model defined based on adjustable parameters.
Parts added must conform to existing construction.
Model may include constraints.
Operation verified during process.
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38. Parametric Modeling Program
(Image Courtesy of SolidWorks Corporation)
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39. Automatic View Generation
Fills need to provide 2D drawings to manufacturing personnel.
Orthographic views most common.
Section, auxiliary, and pictorial views may also be generated.
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40. Computer-Aided Manufacturing
Uses CAD data in computer numerical control (CNC) operations.
Typically used by machining centers.
Tooling movement and speed controlled automatically.
Design data verified before machining.
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41. CAD/CAM Software Program
(EdgeCAM/Pathtrace)
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42. AEC CAD Packages Designed for specific AEC fields.
Special features added to general CAD tools.
Used in both 2D and 3D drawing.
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43. AEC CAD Package Features
Automatic schedule generation
Space diagram creation
Stair generation
Hatch pattern generation
Wall creation
Symbol libraries
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44. Space Diagram Conversion
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45. Common AEC Symbol Libraries
Doors and windows
Structural members
Plumbing fixtures and fittings
Electrical fixtures
HVAC components
Landscaping features
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46. Common AEC Symbol Libraries (Cont.)
Furniture and appliances
Title symbols
Construction details
Vehicles
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47. Door and Window Symbols
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48. Building Information Modeling (BIM)
Form of parametric modeling.
Used in more advanced AEC CAD programs.
Data stored for each construction system in structure.
Components added alter existing structure.
Result may be called virtual building.
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49. Building Information Modeling Features
Cost analysis tools
Automatic generation of plan drawings
Automatic schedule generation
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50. Building Information Modeling Program
(Autodesk, Inc.)
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51. Review Questions
1. A symbol _____ is a collection of standard shapes and symbols used in a particular CAD application.
library
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52. Review Questions
2. A computer mouse is an example of a(n) _____ device.
input
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53. Review Questions
3. A(n) _____ prints object lines on drawings as vectors.
A. laser printer
B. inkjet printer
C. inkjet plotter
D. pen plotter
D. pen plotter
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54. Review Questions
4. Which of the following is not a typical feature found in a general purpose CAD package?
A. Hatch pattern generation
B. Automated dimensioning
C. Editing functions
D. Building information modeling (BIM)
D. Building information modeling (BIM)
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55. Review Questions
5. _____ are similar to transparent drawing sheets on which you can draw.
A. Hatch patterns
B. Layers
C. Linetypes
D. Drawing aids
B. Layers
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56. Review Questions
6. A _____ is a solid model created by extruding a profile along a path.
A. sweep
B. primitive
C. revolution
D. union
A. sweep
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57. Review Questions
7. Special controls called _____ are used in parametric modeling to define size and location dimensions to establish spatial relationships.
constraints
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58. Review Questions
8. A(n) _____ is created by extruding one or more profiles along a special type of path called a rail.
loft
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59. Review Questions
Which type of CAD program is best suited for automated manufacturing?
A. Building information modeling (BIM) program
B. General purpose CAD package
C. CAD/CAM program
D. AEC CAD package
C. CAD/CAM program
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60. Glossary CAD CAD workstation Acronym for computer-aided drafting.
The equipment included in a computer-aided drafting system. A typical workstation includes a computer or processor, monitor, graphics adapter, input and pointing device, and hard copy device.
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61. Glossary Central processing unit (CPU) Command
The primary working center of a computer, where all of the controlling functions and calculations take place. A CPU contains the processor, RAM, and input/output interfaces.
Command
An instruction to a computer that achieves a function when entered.
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62. Glossary Computer-aided manufacturing (CAM)
An automated manufacturing process in which drawing data from a CAD system is used to control the operation of computer numerical control (CNC) machines.
Computer numerical control (CNC)
A computer-operated means of controlling the movement of machine tools.
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63. Glossary Constraints Drawing aids
Special controls that define size and location dimensions to establish spatial relationships between the individual features of a part.
Drawing aids
CAD tools that simplify the tasks of locating positions on screen and on existing objects.
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64. Glossary Inkjet plotters Inkjet printers
Raster output devices used for quick production of large-format prints of CAD drawings.
Inkjet printers
Raster output devices used for quick production of small-size prints of CAD drawings.
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65. Glossary Input device Layers
A computer device (such as a keyboard) used to enter information into a computer.
Layers
On a CAD drawing, user-defined settings that permit the various parts of a drawing to be separated into different layers or “sheets,” much like the transparent drawing sheets in overlay drafting.
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66. Glossary
Loft
A three-dimensional object created by extruding one or more cross-sectional shapes along a path.
Network
A group of individual computers connected to share information and resources.
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67. Glossary Output device Parametric modeling
A computer device used to display a drawing or produce hard copy.
Parametric modeling
A form of 3D-based CAD modeling in which user-defined geometric dimensions control the size and shape of objects and may be altered to change dimensional and spatial relationships.
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68. Glossary
Pen plotter
A traditional vector output device used for generating large-format prints of CAD drawings. A pen plotter uses one or more pens to trace the object lines and “plot” the CAD drawing.
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69. Glossary
Primitives
In CAD modeling applications, building elements drawn to form the basic shapes of a three-dimensional model. Primitives include boxes, cylinders, spheres, and cones.
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70. Glossary Rendering Software
Finishing a presentation drawing to give it a realistic appearance. The term rendering also refers to the actual drawing.
Software
A program used to instruct a computer to perform intended tasks.
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71. Glossary Solid model Surface model
A CAD-generated drawing defined with volume and mass to represent the solid mass of an object.
Surface model
A CAD-generated drawing defined as a wireframe with “skin” placed over the model to represent object surfaces.
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72. Glossary Sweep Symbol library
A three-dimensional object created by extruding a profile along a path.
Symbol library
In CAD applications, a collection of standard shapes and symbols typically grouped by application for use on drawings.
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