1. Shad Valley MUN Introduction to Product Design and Development
Lecture 4: Part 2
Prototyping
Dr. Leonard M. Lye, PEng, FCSCE
Professor of Civil Engineering
Program Director, MUN Shad
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2. Introduction
Prototype = an approximation of the product along one or more dimensions of interest.
Alpha prototypes: Used to assess whether product works as intended. Similar in material and geometry as production version, but made differently. E.g. machined instead of molded.
Beta prototype: Used to assess reliability and to identify remaining bugs in the product. Given to customers for testing in the use environment. Parts are usually made with the actual production process and supplied by intended parts suppliers. Assembled by team rather than the manufacturer.
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3. Four Uses of Prototypes
Learning
answering questions about performance or feasibility
e.g., proof-of-concept model
Communication
demonstration of product for feedback
e.g., 3D physical models of style or function
Integration
combination of sub-systems into system model
e.g., alpha or beta test models
Milestones
goal for development team’s schedule
e.g., first testable hardware
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4. Physical vs. Analytical Prototypes
Physical Prototypes
Tangible approximation of the product.
May exhibit unmodelled behavior.
Some behavior may be an artifact of the approximation.
Often best for communication.
Analytical Prototypes
Mathematical model of the product.
Can only exhibit behavior arising from explicitly modelled phenomena. (However, behavior is not always anticipated.
Some behavior may be an artifact of the analytical method.
Often allow more experimental freedom than physical models.
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5. Focused vs. Comprehensive Prototypes
Focused Prototypes
Implement one or a few attributes of the product.
Answer specific questions about the product design.
Generally several are required.
Comprehensive Prototypes
Implement many or all attributes of the product.
Offer opportunities for rigorous testing.
Often best for milestones and integration.
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6. Comprehensive Prototypes
Many comprehensive
prototypes are built.
Some comprehensive
prototypes build (and sold?).
High
Technical or Market Risk
One prototype may be
used for verification.
Few or no comprehensive
prototypes are built.
Low
Low
High
Cost of Comprehensive Prototype
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7. Prototyping Strategy Use prototypes to reduce uncertainty.
Make models with a defined purpose.
Consider multiple forms of prototypes.
Choose the timing of prototype cycles.
Many early models are used to validate concepts.
Relatively few comprehensive models are necessary to test integration.
Plan time to learn from prototype cycles.
Avoid the “hardware swamp”.
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8. Rapid Prototyping Methods
Most of these methods are additive, rather than subtractive, processes.
Build parts in layers based on CAD model.
SLA=Stereolithography Apparatus
FDM=Fused Deposition Modelling
3D Printing
LOM=Laminated Object Manufacturing
Others every year...
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9. 3-D Printing Similar to a photocopier except that it prints in 3-D.
Check out
Build it yourself 3-D printing device
And
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10. Virtual Prototyping 3D CAD models enable many kinds of analysis:
Fit and assembly
Manufacturability
Form and style
Kinematics
Finite element analysis (stress, thermal)
Crash testing
more every year...
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11. From: Scientific American, March 1999
BMW Virtual Crash Test
From: Scientific American, March 1999
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12. Traditional Prototyping Methods
CNC machining
Rubber molding + urethane casting
Materials: wood, foam, plastics, etc.
Model making requires special skills!
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13. Planning for Prototypes – 4 steps
Step 1: Define the purpose of the prototype.
What is the prototype for? Is it for learning, communication, integration, or milestone?
Step 2: Establish Level of Approximation.
Is an analytical prototype good enough or a physical prototype necessary? Should it “works like” or just “looks like”?
Step 3: Outline an Experimental Plan
Decide on what measurements have to be taken. What combinations of configurations need to be tested? Test conditions?
Step 4: Create a Schedule for Procurement, Construction, and Testing.
Prototyping is a sub-project within the overall product development project. What parts need to be ordered, assembled? When must it be completed? How much time for testing?
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14. Summary
Prototypes are used for learning, communication, integration, and milestones.
Physical prototypes are best for communication, and comprehensive prototypes are best for integration and milestones.
Analytical prototypes are generally more flexible than physical prototypes.
Physical prototypes are required to detect unanticipated phenomena.
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15. Summary (Continue)
3-D computer modelling and free-form fabrication technologies have reduced the relative cost and time required to create prototypes.
A 4-step method for planning prototype is:
Define the purpose of the prototype
Establish the level of approximation of the prototype.
Outline an experimental plan
Create a schedule for procurement, construction, and testing.
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16. Thought Question
Some companies have reportedly abandoned the practice of doing a customer test with the early prototypes of their products, preferring instead to go directly and quickly to market in order to observe the actual customer response. For what types of products and markets might this practice make sense?
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