Download - Professor abubakr lecture 1 cad 2016
06-Oct-15
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Helwan University
Faculty of Engineering
Mechanical Engineering Department
CAD
Dr. Abu Bakr Ibrahim Abd El Wahab
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Lecture 1 CAD 2014/2015
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What is “Engineering Design Process” ?
“Design is the process of conceiving
or inventing ideas and تصور
communicating those ideas to others in
a form that is understood easily.”
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“A systematic process by which
solutions to the needs of humankind
are obtained.
What is “Engineering Design Process” ?
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“The act of creating the specifications
for a product or process that best
satisfies the design criteria.
What is “Engineering Design Process” ?
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What is “Engineering Design Process” ?
Step 1 •Identify the need or problem
Step 2 •Research the need or problem
Step 3 •Develop possible solutions
Step 4 •Select the best possible solution
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What is “Engineering Design Process” ?
Step 5 •Geometric Model
Step 6 •Test and evaluate the solutions
Step 7 •Communicate the solutions
Step 8 •Redesign
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Cost
Time
Once a design is released for production, the
cost of making changes grows exponentially
Late changes increase costs and extend
production schedules
Manufacturing
Documentation:
Drawings for
tool/fixtures,
instruction
manuals, etc. Design
Manufact
uring,
Assembly,
Testing Hard tooling
produced:
dies, molds,
fixtures, etc.
Product Development Cycle Costs
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Cost
Time
Manufacturing
Documentation:
Drawings for
tool/fixtures,
instruction
manuals, etc. Design
Manufact
uring,
Assembly,
Testing Hard tooling
produced:
dies, molds,
fixtures, etc.
Product Development Cycle Costs
Early decisions have large influence
Late changes are very costly
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What is the Geometric Model?
Collection of methods used to define the
shape and other geometric characteristics
of an object.
Step 5 •Geometric Model
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Precise mathematical description of the
shape of a real object or to simulate some
process.
Step 5 •Geometric Model
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Geometric Model
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How to Construct the Geometric Model?
Using CADD software
AutoCAD, TurboCAD, SolidWorks, Catia,
Master CAM, Pro/Engineer
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Construct the Geometric Model
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15 Revolution axis of the cup’s main body
Construct the Geometric Model of cup’s main body
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Construct the Geometric Model: Profile curve of the
handle
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Construct the Geometric Model:
Sweep path of the handle
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Line drawing of the cup
Construct the Geometric Model
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Construct the Geometric Model
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More Examples of Geometric Model
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More Examples of Geometric Model
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More Examples of Geometric Model
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More Examples of Geometric Model
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Test and evaluate the solution - Engineering analysis:
Step 6 •Test and evaluate the solutions
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Test and evaluate the solution - Engineering analysis:
Evaluate each solution may require finite element
modeling, shape optimization, kinematics simulation,
circuit analysis, Computer Aided Inspection and
Heat analysis, …
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Finite-Element Method
Calculate stress, strain, displacement etc. at any
place in the model by solving a set of system
equations and shape functions on the mesh
Finite Element Shapes
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Meshing
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FEA of Our Cup
Stress distribution map
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An Example of FEM in Gas Tank Design
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Communicate the solution
Computer-aided drafting and design, CADD
Step 7 •Test and evaluate the solutions
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1. Increased accuracy
3. Easy to revise
2. Increased drawing speed
5. Built-in several analysis tools
6. Better presentation (Easy to visualize), Pan, rotate,
animate, shade, texture
4. Availability of drawing libraries
Advantages of CADD
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Draw
Modify
Sweeping
Revolve
Extruded Solid
Sectioning
Trim
Extend
Offset
Move
Copy
Stretch
Mirror
Trim
Erase
Fillet
Rotate
Chamfer
Array
Dimensioning
Layer concept
Limits
Zooming
Units
CADD
Capability
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Redesign
Step 8 •Redesign
Modify the design geometry (CAD again)
Get feedback from Test
Evaluate the solution
Engineering analysis and
Communication
Modify the design geometry accordingly
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Modifying the Design Geometry
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Modifying the Design Geometry
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Stress distribution map of the modified cup
FEA of the Modified Cup
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What after Engineering Design Process?
CAM
Step 1 • Identify the need or problem
Step 2 • Research the need or problem
Step 3 • Develop possible solutions
Step 4 • Select the best possible solution
Step 5 • Geometric Model
Step 6 • Test and evaluate the solutions
Step 7 • Communicate the solutions
Step 8 • Redesign
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CAM Manufacturing process planning
Plan, manage, and control manufacturing process
Numerical control (NC) machining
The technique of using programmed instructions to
control a machine tool that grinds, cuts, mills
punches, bends, or turns raw stock into the finished
part.
Rapid prototyping
Build a prototype of the part directly from the CAD
model as a stack of layers by means of laser or other
techniques.
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Figure 3. A schematic drawing of an SLA process.
StereoLithography
Rapid Prototyping
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CAD/CAM:
Integration of design and manufacturing
activities by means of computer systems.
The method of manufacturing a product is
a direct function of its design.
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ماهو الفرق بين كل من
CAD CAM CAD/CAM
CAD: Product design, engineering analysis, and
documentation of the design (e.g., drafting)
CAM: Process planning, NC part programming,
,material requirements planning, production
scheduling, computer production monitoring,
and computer process control, Inspection and
Assembly
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CAD/CAM denotes an integration of design
and manufacturing activities by means of
computer systems and computer science.
The method of manufacturing a product is a
direct function of its design.
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ماهو الفرق بين كل من
Conventional procedures & Ideal CAD system
Conventional procedures :Engineering drawings were
prepared by design draftsmen and then used by
manufacturing engineers to develop the process plan
(i.e., the route sheets).
Product design were separated from CAM
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Disadvantage of Conventional CAD procedures
ماهي عيوب ذلك
Two-step procedure was employed
Time consuming
Duplication of effort by design and
manufacturing personnel.
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Ideal CAD/CAM:
1.Automate CAD phases
2.Automate CAM phases
3.Direct link is established between CAD & CAM
4.Automate the transition from design to
manufacturing.
CAD CAM
Ideal Conventional procedures
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Ideal CAD/CAM system:
Take the design specification of the product as it
resides in the CAD
Automatically Convert it into a process plan for
making the product,
NC part program would be generated
automatically
NC program would then download directly to
the machine tool by means of a
telecommunications network.
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Case Study:
You saw very dirty window panels in your lecture room
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Cause:
Maybe, a person responsible to this job is lazy.
I don’t think so. I saw he worked hardly
.................
................
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Step 1 •Identify the need or problem
Step 2 •Research the need or problem
Step 3 •Develop possible solutions
Step 4 •Select the best possible solution
Step 5 •Geometric Model
Step 6 •Test and evaluate the solutions
Step 7 •Communicate the solutions
Step 8 •Redesign
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You asked him, why don’t you clean those windows ?
He said it is impossible to clean those windows.
So, what do you think ?
Look at the windows again, then you will
understood his answer.
What are your findings ?
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?
?
You found that the windows have two glass panels
One is fixed to the top, another one is fixed to the
bottom of a window frame.
Both panels place offset with each other and their
free edge overlap about mid of the window’s height.
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Sorry, I cannot imagine about the window you have
explained.
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Okay, I will show you a sketch of the windows.
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Visualization
&
Communication
&
Documentation
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The Role of Graphics
Visualization Communication Documentation
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Sorry, I still do not understand why it is hard
to clean the window
Um.. . I will show you the side view of this
window.
The glass panel
is thin, so he omits
section lines !
Visualization
&
Communication
&
Documentation
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Ah.. I see. The offset distance is small, so he
can not access the opposite side of the
window and the overlapped zone.
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That is right !. If we do not solve this problem,
learning environment will become worse and
…….
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To design a device that can clean the opposite
side of glass panel and overlapping area
effectively.
Identify the need or problem
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Develop possible solutions.
1. Hire a cleaning service company.
2. Buy a usable device.
Individual Teamwork
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Develop possible solutions.
3. Design a homemade cleaning device.
5. ………………………
4. Redesign the window construction.
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Develop possible solutions. 3. Design a homemade cleaning device.
i- Modify from an existing solution.
ii. Ad hoc (Unplanned) solution. التصميم من ال شيئ
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Major functions of a device
1. Wash & Polish
2. Wipe
Solution Feature
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Would you like to combine both functions
into a single device or :?
1- Single device
2- Single device but has a changeable part
3- Two devices:
One for wash & polish, another for wipe.
Assume you (or your team) choose:
Single device
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Major functions of a device
Wash
Polish
Wipe
Hold (by user)
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Easy to use.
Should not rust.
Not too expensive
Not too heavy.
Can insert between the panels.
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What should be an appropriate form of part(s)
to do the required functions?
What material is the part should be made of ?
How parts are assembled ?
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Function
What material is the part
should be made of ?
What should be an
appropriate form of
part(s) to do the
required functions?
How parts are assembled ?
Not too heavy.
Not too expensive.
Can insert between the panels.
Hold
(by user)
Polish
Should not rust.
Easy to use.
Major functions of a device
Wash
Wipe
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“Design a homemade cleaning device”
Is your decision is the best solution ?
Criteria !!!!
Evaluate each solution against the criteria
and select the best one.
Brainstorming
Brainstorming expands one’s thinking to
include all the dimensions of a problem
or its solution
Brainstorming is used to help a group
create as many ideas as possible in
as short a time as possible
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Goal wishing -Free-thinking
It is totally without regard to feasibility -
non-judgmental
New ideas often start out as totally
ridiculous
Some of the more important things to do and avoid:
a. Do go first for quantity
b. Avoid evaluating (looking for quality)-that comes
later
c. Avoid assumptions about limits, restrictions etc.
d. Do write everything down.
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e. Write down and keep visible the central topic
f. Don’t criticize ideas or suggestions
g. Write down all ideas as spoken, and keep them
visible to the participants
h. Every participant/student is asked to
present an idea
i. Participant/Student give ideas as they
come to mind
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Possible solutions.
1.
2.
3.
5.
4.
Possible solutions.
1. Hire a cleaning service company.
2. Buy a usable device.
3. Design a homemade cleaning device.
5. ………………………
4. Redesign the window construction.
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C
Assume you (or your team), Choose the solution C
A B
C
Example of mathematical analysis Operation
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Evaluate each solution against the criteria and
select the best one
This is the initial evaluation step
Discuss the Pro فى الجانب المؤيد /con الموقف السلبي
Picks one or more directions that hold some
attract
States the concerns.
Removing obstacles or concerns
As concerns are addressed, they get a little
more realistic
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Cost Weight … Size Solutions
Ease of operation
Evaluate each solution against the criteria and select the best one.
Criteria
A B
C
Mathematical analysis
Computer simulation
Build and test a prototype
Tools for evaluating the solutions :
Freehand
sketching is
used to
represent
rough ideas.
Document the solution.
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CAD Homework #1
1- What are the most important components of Engineering Design
Process?
2- Describe product development cycle costs and the outcome from
the cost – time relationship.
3- How to construct the Prototype / Geometric Model? . Give an
example
4- How to evaluate each solution
5- In the steps that you answer in 1, which one uses Computer-aided
drafting tool, which one uses Finite-Element tool, and which one
uses CAM tool?
6- What is the most widely used CADD Capabilites?
7- What is the most widely used CADD software ?
8- Describe the difference between Conventional procedures &
Ideal CAD procedures?
9- What is Numerical Control Machining?
10- What are the steps of brain storming cession?
Professor Abubakr Lect 1 CAD 2016