Prototyping

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Prototyping

• Reference Ulrich and Eppinger, Product Design
  and Development, 2nd ed., Chapter 12

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Prototyping

• An approximation of the product along one or more
  dimensions of interest
• Industrial designers ? concepts
• Engineers ? a design
• Software developers ? a programming concept

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Prototyping

• Types
• Analytical vs Physical
• Analytical Intangible mathematical investigate
  interesting aspects
• Physical Tangible approximate the product or
  parts of the product
• Comprehensive vs Focused
• Comprehensive Full-scale, fully operational
• Focused Implement one or a few attributes of the
  model often looks like or works like

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Prototyping
Physical
Comprehensive
Focused
Not Generally Feasible
Analytical
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Prototyping

• What are prototypes used for?
• Learning
• Will it work? Does it meet the customers needs?
• Communication
• Look and feel
• For management, vendors, extended team, investors
• Integration
• Do parts, subsystems, systems work together?
• Milestones

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Prototyping

• Principles
• Analytical generally more flexible than
  physical
• Physical detect unanticipated phenomena
• Prototypes can reduce iteration process
• Prototypes may expedite other development stages
• Prototypes may restructure task dependencies

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Example Physical Prototype
Student Project Automatic CD Changer
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Prototyping

• Modern Technologies
• Computer modeling
• 3D modeling shape, size, fit, kinematics
• Finite Element stress, strain, deflection
• Free-form fabrication
• Rapid prototyping Stereolithography

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Kinematics
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Finite Element Analysis
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Finite Element Analysis
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Rapid Prototyping
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Rapid Prototyping Sequence

• CAD solid model
• .STL file
• Slicing the file
• Final build file
• Fabrication of part
• Post processing

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CAD Solid Model

• Solid model or closed surface model required

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.STL File

• Software generates a tessellated object
  description
• File consists of the X, Y, Z coordinates of the
  three vertices of each surface triangle, with an
  index to describe the orientation of the surface
  normal
• Support generation to hold overhung surfaces
  during build

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Slicing the File

• Series of closely spaced horizontal planes are
  mathematically passed through the .stl file
• Generate a .sli file a series of closely
  spaced 2D cross-sections of the 3D object
• Typical Z thickness 0.006 (0.150 mm)
• Other Parameters chosen fn(RP technology)

like a stack of pancakes!!
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Final Build File

• Part sliced
• Supports sliced
• RP technology parameters set
• layer thickness, scan speed,...
• Send file to RP machine

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Stereolithography SL

• 3D Systems, Valencia, CA
• patent 1986, beginning of RP
• photopolymerization using UV laser
• epoxies, acrylates
• accuracy lt 50 microns

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Stereolithography SL
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Stereolithography SL
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Stereolithography SL
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Fabrication of Part
Models built on stereolithography apparatus.
Part and supports shown attached to platform.
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Post-processing

• Removal of part from platform
• Removal of supports from part
• Cleaning of part (wiping, rinsing, ... )
• Finishing part (sanding, polishing, )

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SL Examples
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SL Examples
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Prototyping

• Planning process
• Define the purpose
• Learning, communication, integration, milestone
• Establish the level of approximation
• Analytical/physical focused/comprehensive
• Outline an experimental plan
• Create a schedule for procurement, construction,
  and test

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Prototyping

• Milestone prototypes
• Provide tangible goals
• Demonstrate progress
• Enforce the schedule

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Prototyping

• Types of milestone prototypes
• Alpha
• Similar shapes/materials often different
  production processes
• Used to assess if product works as intended
• Beta
• Use production processes, assemble by hand
• Used to assess reliability identify bugs
• May be given to customers
• Preproduction
• First products of entire production process
• Provide test product
• Validate production process