Parametric DesignModeling

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Parametric Design/Modeling
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Mass Production
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Mass Customization
Bevel Head
Create reusable generic models
Mature Product
Polish Pin
Obtain draw Wire
Cut Wire
Make Point
x
x
x
x
Select best process
x
Create a standard work template
Standard Work
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Parametric Design - Applications
Parametric Model
Editing a feature
DESIGN/MODELING
FINITE ELEMENT MESHING
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Parametric Design - Applications
FINITE ELEMENT MESHING
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Parametric Design - Applications
D Diameter of the Hole H Depth of the
Hole Cost for Drilling f(D, H,)
A lt Allowable Clearance will damage the part
while drilling
MANUFACTURING COST EVALUATION
MANUFACTURABILITY ANALYSIS
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Parametric Design - Applications
e.g. Accessibility is a feature A1 (parameter)
Removal direction of the part P1
e.g. Clearance is a feature A (parameter)
minimum distance between the parts P1 P2
P2
P1
P1
ASSEMBLY DESIGN
MAINTENANCE
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Parametric Design/Modeling

• Requirements
• Geometric modeling features described in terms of
  input key parameters and relationships.
• A set of key dimensional and functional explicit
  input parameters that accurately describe a part,
  assembly, or system.
• A set of relationships that describe all other
  implicit dimensional and functional parameters in
  terms of the explicit inputs.
• Third generation CAD instantiation engine or
  system.

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Features Parameters
Parameterized Model

• Features are high-level representation of a
  product/process around which
• engineering knowledge and expertise are
  structured.

• Parameters are variables representing values and
  relationships associated
• with a product/process.

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Parametric Design/Modeling

• What are the geometric modeling features required
  to create the sprocket?

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Parametric Design/Modeling
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Parametric Design/Modeling

• Are there other features that could be combined
  to build a generic sprocket?

• Are there other features that could be combined
  to build a generic sprocket?

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Parametric Design/Modeling
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Parametric Design/Modeling

• There still other features that could be combined
  or subtracted to build a generic sprocket.
• Which of all the feature structures is most
  robust?
• Why?
• Is one more preferred?
• Why?

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Parametric Design/Modeling

• What is the backward mapping approach to a
  feature structure?
• 1. Visualize and Sketch the part or component.
• 2. Determine what modeling feature was added
  last.
• 3. Sketch this feature separately and Remove it
  from the sketch of the part or component.
• 4. Repeat steps 2 and 3 until all features have
  been identified sketched and removed leaving only
  a primitive or basic feature.

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Parametric Design/Modeling
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Parametric Design/Modeling

• What are some key parameters necessary for the
  creation of a sprocket model?
• teeth (N)
• Pitch length (P)
• Bore diameter (B)
• Two questions to consider
• Are there other key design parameters?
• What about system or performance level
  parameters?

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Parametric Design/Modeling

• System/Performance key parameters
• Torque to be transferred (T)
• Speed RPM (S)
• Strength/Life (L)

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Parametric Design/Modeling

• Dimensional or Geometric parameters
• Number of teeth (N)
• Pitch length (P)
• Bore diameter (B)

Key

• Tooth form
• Pitch diameter (D)
• Root diameter (Dr)
• Outside diameter (Do)
• Side slope (?)
• Tooth thickness (t)
• Roller diameter (R)

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Parametric Design/Modeling

• What is the backward mapping approach to a set of
  key parameters?
• 1. What are the system level inputs that impact
  the part or component?
• 2. Give them appropriate names.
• 3. What are the minimal dimensional and geometric
  inputs required to describe or create the
  features?
• 4. Give them appropriate names.

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Parametric Design/Modeling

• In the discovery and development of key
  parameters we often struggle with parameters that
  can be defined either as explicit inputs or
  implicit relationships or both.
• To minimize the struggle define both parameters
  and relationships concurrently, making sure that
  together they provide qualified control of system
  and dimensional/geometric features.

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Parametric Design/Modeling

• What would be some relationships for a sprocket?

• Are there others? What are they?

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Parametric Modeling - Fan Example
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Parametric Modeling - Fan Example
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Parametric Modeling - Fan Example

• List the backward mapping modeling features.
• List the key parameters.
• List the relationships.