The slide presents introduction to computer aided design and drafting, and introduction to AutoCAD software. 2D and 3D modelling using AutoCAD software is presented.

1. By: Mr. Ashenafi B. (M.Sc.)
Introductionto CAD
Arba Minch University
Sawla Campus (AMU-SC)
Electromechanical Department

2. Design-Manufacturing Process
Old (before computer era)
Sketch with
pencils
Engineering Drawing
with pencils
Manufacturing

3. Sketch
http://www.buzzle.com/articles/leonardo-da-vinci-
inventions.html
http://youtu.be/Rog5i2n1QVs

4. Eng. Drawing- http://modelenginenews.org/cardfile/m42.h

5. Eng. Drawing -Part

6. Manufacturin http://modelenginenews.org/cardfile/m42.html

7. Now…. with
computer
CAD (Solid
Modeling)
Engineerin
g Drawing
Manufacturin
g
CAA (Computer
Aided Analysis)
CAM (Computer
Aided
Manufacturing)
/Direct
Manufacturing
CAD is a starting point of everything!
Check, http://en.wikipedia.org/wiki/Computer-

8. http://www.cob.unt.edu/slides/Peak/old%205130/Class%2010/Animat
Computer-Aided Engineering (CAE)
 Use of computer systems
to analyze CAD geometry.
 Allows designer to
simulate and study how
the product will behave,
allowing for optimization.
 Finite-element method
(FEM)
 Divides model into
interconnected elements
 Solves continuous field
problems.

9. http://cadcamfunda.com.p.in.hostingprod.com/cadcam_softwares
Computer-Aided Manufacturing (CAM)
 Use of computer systems to plan, manage, and
control manufacturing operations.
 Direct or indirect
computer interface
with the plant’s
production
resources.
 Numerical control
of machine tools.
 Programming of
robots.

10. CAM http://blog.iqsdirectory.com/process-equipment/automation-
equipment-lost-jobs-or-efficient-production/

11. In this course, we will
cover
CAD (Solid
Modeling)
Engineerin
g Drawing
Manufacturin
g
CAA (Computer
Aided Analysis)
CAM (Computer
Aided
Manufacturing)
/Direct
Manufacturing

12. What is CAD?
 Originally CAD includes any techniques that use
computers in the design process including drafting,
stress analysis and motion analysis.
 But over the last 35 years, CAD has come to refer more
specifically to Computer Aided Design and Drafting.
 CAD program/software is an electronic tool that
enables you to make quick and accurate orthogonal
and 3D drawings with the use of a computer software
packages.
 Computer drawings are neat, clean, highly presentable,
and can be modified easily.
 With CAD, parts or components can be modeled,
visualized, revised, and improved on the computer
screen before any engineering drawings have been
Computer Aided Design (CAD)

13. Capabilities of CAD
Some of the important capabilities of using CAD
are;
1) Presentations
- You can create fine drawings with
presentation symbols and text styles.
- You can use CAD program to make on
screen presentations.
2) Flexibility in editing
- CAD provides the flexibility to make quick
alterations to drawings
- Some of the editing capabilities are such as;
move or copy drawing elements, enlarge or
reduce size of a drawing, make multiple
copies of a drawing, change units of measure

14. 3) Units and accuracy level
- CAD program allows you to work with
great accuracy. You can also work with
different units of measure, such as
architectural units, engineering units,
scientific units and surveyor units.
4) Storage and access of drawings
- It is quick and convenient to organize
CAD drawings. You can have thousands of
drawings on a computer’s hard disk and
you can open any one of them within
seconds.
Capabilities of CAD (Cont.)

15. 5) Sharing CAD drawings
- The drawings can be shared by a number of
users, allowing them to coordinate projects and
work as a team. This is accomplished by
connecting different computers via a network.
You can also publish your drawings on the
Internet and collaborate CAD projects using a
web site.
6) Project reporting
- The computer can be used to prepare project
reports.
7) Engineering analysis
- There is a separate category of programs
Capabilities of CAD (Cont.)

16. 8) Computer aided manufacturing (CAM)
- CAM is a common method of
manufacturing used by large corporations.
- These systems import CAD drawings into
CAM programs to automate the
manufacturing process.
Capabilities of CAD (Cont.)

17. CAD Drawbacks
•Initial cost of hardware and software
•Need to re-train staff
•Computers may crash and drawings are lost
•Security of files; files may be hacked
•Need to update software
Fig: Line drawing
plus rendering

18. CAD Models
 A CAD model is a computer representation
of an object or part.
 It contains all of the design information
including geometry, dimensions,
tolerances, materials and manufacturing
information.
 CAD models replace the paper blueprints
and engineering drawings
 The simplest model used in CAD is a 2D
model. This model is essentially the
computer graphics equivalent to an
orthographic projection.

19. CAD Models (Cont.)
 A 3D model is the most general model used
in CAD software. This model is equivalent to
an isometric view.
 2 basic types of 3D models are wire frame
and surface models.
 In a 3D wire frame model, only edges of the
object are represented.
 A 3D surface model defines the object in
terms of surfaces such as plates (flat) and
shells (curved) in addition to edges.

20. Solid Modeling
 The current state of the art in CAD, is the
most sophisticated method of
representing an object.
 Unlike wire frame or surface models, a
solids model represents an object in the
virtual environment just as it exists in
reality, having volume as well as surfaces
and edges. In this way, the interior of the
object is represented in the model as well
as the outer surfaces.

21. Use of solid models
 Can be used for stress analysis, heat
transfer analysis, fluid flow analysis, and
computer aided manufacturing.
 In the manufacturing process, to
automatically generate machine tool paths to
machine an object.
 To simulate the removal of material from an
initial block of material on the computer
 Can be linked to Computer Numerical
Control (CNC) machine to carry out the
removal of material automatically allowing
many identical parts to be machined based
directly on the solid models.

22. CAD Process
 Two types of activities: synthesis and
analysis.
 Synthesis is largely qualitative and
hard to capture on computer.
 Analysis can be greatly enhanced with
computers
 Once analysis is complete, design
evaluation- rapid prototyping
 Software packages for design
optimization

23. Components of CAD/CAM/CAE
Systems
 Major component is
hardware and software
allowing shape
manipulation:
 Hardware includes graphic
devices and their peripherals
for input and output
operations.
 Software includes program
packages that manipulate or
analyze shapes according to
user interaction.

24. Hardware Components
 Graphic device is composed of a display
processing unit, a display device, and one
or more input devices
 Input devices:
 Mouse
 Space ball
 Data tablet with a puck or stylus
 Keyboard
 Output Devices:
 Plotters
 Color laser printers

25. Software Components
 CAD software allows the designer
to create and manipulate a shape
interactively and store it.
 CAM software plans, manages and
controls the operations of a
manufacturing site
 CAE software analyzes design
geometry, allowing designer to
study product behavior.

26. Rapid Prototyping
 Layer by layer fabrication of
3D physical models from
CAD.
 Fast and inexpensive
alternative for producing
prototypes and functional
models.
 Build parts in thin layers.
 Minimum operation time;
typically runs unattended.
Rapid Prototyping
has surgical
applications
 In addition to providing 3D visualization for
digitally rendered items, it can be used to test
the efficiency of a part/product design before
manufacturing in large quantities.

27. Rapid Prototyping Cycle

28. CAD software
• AutoCAD, SolidWorks, Pro/Engineer,
CATIA, ……
• Which one is the best?
Depends what you want.
• In this course, we are reliant on AutoCAD
software.

29. Introduction to AutoCAD
AutoC
AD

30. Cont.
 AutoCAD is an abbreviation stands for Automated
Computer Aided Design/ Drawing /Drafting which is
an application software that designers (Engineers &
Architects) use in their daily design activities and it by
far, helps in reducing the bulk of work to be done, had
the design been with ruler and pencil.
The use of CAD process provides enhanced graphics
capabilities which allows any designer to:
 Conceptualize his ideas
 Modify the design very easily
 Perform animation
 Make design calculations
 Use colures, fonts and other aesthetic features

31. Advantage of AutoCAD
 AutoCAD enhances the productivity and
quality of designs.
 Drawings get prepared in relatively
shorter duration.
 Reduced the manpower requirement .
 AutoCAD software is cost effective and
highly affordable.
 Designs can be drawn with greater
accuracy.
 Facilitates easy modification and revision

32. I. Drawing Area: To provide space to prepare a drawing.
II. Menu Area: To allow the entry of various commands for
preparing the drawings.
III. Command Area: It consists number of dialog boxes which can
be utilized for preparing the drawings.
IV. Tool Area: To allow selection of various options for the drawing.
AutoCAD package utilize four areas on the screen:

33. AutoCAD Window

34. HOW AutoCAD WORKS
 There is a co-ordinate system used in
AutoCAD.
 Every drawing shows its co-ordinate.
 There is so many commands like copy,
move ,rotate ,mirror in 2D, array , offset,
chamfer, fillet & more.
 Different types of drawing can be made in
the same time by using a command that is
LAYER.
 Using line , arc , circle , rectangle , ellipse &

35. Co-Ordinate System
 Every thing that we draw in AutoCAD is exact.
 All object drawn on screen is based on simple X-Y
coordinate system.
 In AutoCAD it is known as world co-ordinate system (WCS).
 We are drawing a line, so we have two points A(-10,-4) and
B(9,6). As shown in figure.

36. UCS vs WCS
 The AutoCAD world is 3 dimensional. However, if
we want to draw a 2d object, such as a plan or a
section, we will use only 2 dimensions (x and y).
 WCS (world coordinate system) is the imaginary
plane that is parallel to the ground. It is the default
coordinate system.
 Modifications made to the World Coordinate
System (WCS) result in a User Coordinate System
(UCS). It is the plane that you work on. It enables
the user to draw 3 dimensional objects.
 To create a new UCS, type ‘ucs’ on the command
window, then say New and specify 3 points on your

37. Angle Measurement in AutoCAD
 Positive degrees are measured counter clockwise
starting from 3 o’clock that means from positive x-
axis. Clockwise angle measurement results negative
degree.

38. Way to Provide Commands
1. Keystrokes/ Using Key
Board
2. Drop Down Menu
3. Shortcut Icons

39. Ways of Inserting Point Commands
1. Absolute Co-ordinate Entry
X,Y
2. Relative Co-ordinate Entry
@X,Y
3. Polar Co-ordinate Entry
@D<A

40. Basic Drawing and Modifying Commands

41. Example-1

42. More Commands (i.e. Modifying & OSnap)

43. Example-2

44. Assignment-1

45. Assignment-2

46. Selecting Objects in AutoCAD

47. Important Modifying Commands

48. Example-3

49. Power Modifying Commands

50. Example-3

51. Assignment-2

52. Layers, Dimensioning, Text & Scale

53. Example-4

54. Direct Distance Entry & Object Tracking
 Direct Tracking (ORTHO): Direct distance
entry. Constrains cursor movement to the
horizontal or vertical.
 Polar Tracking (POLAR): Polar distance
entry.
 Object Snap Tracking.

55. Polyline Commands & Layouts

56. Hatching-Filling Areas

57. Three-Dimensioning (3D)
Drawing

58. Example-1

59. Example-2

60. Example-3

61. Example-4

62. Example-5

63. Assignment-4

64. End!!