1. Building and testing prototypes
Why test?
Form, fit & function
Types of tests
Types of prototypes
Test plans
Summary

2. Why Do Product Testing?
Finished parts do not always look the same as designed
Finished parts do not always fit together as designed
Finished parts do not always work the way they were designed.

3. What do “form” tests determine?
Form test– Will the part/product have an acceptable appearance?

4. What do “fit” tests determine?
Fit test – Will the parts fit together or fit the user, with an acceptable precision?

5. What do “function” tests determine?
Function – Will the part/product perform as required?

6. Tests: Types & Timing -A
Formulation
Concept Design
“Proof of Concept” tests
validate physical principles
“Product Concept” tests
validate product / appearance

7. Product concept and Proof-of-concept models
Mercedes F700

8. Tests: Types & Timing - B
Parametric Design
Configuration Design
“Virtual prototype” tests
solid modeling CAD
“Alpha prototype” tests
actual geometry & materials
but may not use actual mfg. processes

9. Virtual prototype
Mercedes F700
MIT Smart City 2020

10. Alpha prototype The flying saucer
Sky Commuter is on the block on ebay. Starting bid: $55,600.
Labels: Future Past, Technology
The flying saucer

11. Tests: Types & Timing - C
Detail Design
Manufacture
“Beta prototype” tests
parts made with planned mfg. processes
volunteer customers / panel
actual operating conditions, environment
“Preproduction prototype” tests
parts made with final mat’s & processes
independent labs: UL, CPSC, NHTSA

12. need physical “prototype”
Testing Sequence
Product concept
Proof of concept
Virtual prototype
Alpha prototype
Beta prototype
PreProduction prototype
less expensive
more expensive
need physical “prototype”

13. More prototypes
Toyota Winglet
Toyota i-Real
Toyota i-Foot
Toyota PM

14. Physical Prototypes
Prototype… is a replica or model of the part showing principal geometric features
Prototypes differ in:
Scale - Reduced, Full, Expanded
Fabrication Process - Same as mfg, Similar, Different
Material - Same as final, Different, Similar
Two ways to make prototypes:
Traditional
Rapid

15. Traditional prototypes
Clay models of new auto body for appearance testing,
Wood models of heavy equipment patterns for metal castings,
Manually machined metal airplane wings for function testing in a wind tunnel,
Reduced-scale balsa wood models of large facilities, to examine equipment layout.
Clay modeling: 1, 2, 3, 4, 5

16. Some Disadvantages of Traditional Prototyping
Uses tools and fabrication methods that are labor intensive.
Often require significant mechanical or artistic skills.
Take a long time to fabricate an original.
Revisions may require complete rebuilding of part
Costly for duplicates.
May not facilitate tooling design and construction

17. Rapid Prototyping NC/CNC Machining Selective Laser Apparatus
Fused Deposition Modeling
3-D Ink Jet
Laminated Object Manufacturing
Selective Laser sintering
Service Bureaus

18. NC/CNC Prototyping (Subtractive process)
workstation
Solid Modeling
CAD software
Saved Part
Solid model file
*.PRT
NC code generation
NC Machine instruction code
file
NC/CNC Machine
e.g. mill, lathe
Fabricated
Prototype

19. Numerical Control Machining (NC/CNC)
CAD files are converted to NC – machine instruction codes for automatic machining
Part can be made of metal
Dimensions have excellent tolerances
Multiple copies of parts can be made easily
Prototyped parts are well suited for form, fit and function tests
CNC

20. NC Machined part example
Mars rover wheels
(Courtesy of HAAS Automation)

21. Rapid Prototyping – Additive processes
Solid Modeling
CAD software
Rapid Prototyper
Slicing Program
Faceted
Model file
*.STL
Saved Part
Solid model file
*.PRT
Fabricated
Prototype
RP Machine instruction code
file
RP Machine
workstation

22. Stereo Lithographic Apparatus (SLA)
laser
projection
mirror
(xy-axes)
elevator
(z-axis)
Photopolymer
(liquid resin)
object being prototyped
tank
Solidified lamina
SLA

23. (Courtesy of 3D Systems)
3-D Systems SLA 7000
(Courtesy of 3D Systems)

24. SLA Jaguar manifold
(courtesy 3-D Systems, Inc)

25. Stereo Lithography Apparatus (SLA)
Parts exhibit superior finishes
polymeric prototypes are weaker than metal prototypes (i.e.CNC)
Prototyped parts are well suited for form, and fit tests.
Some function testing

26. Selective Laser Sintering (SLS)
Uses a high power laser to sinter together fusible materials, such as powdered metals, layer by layer.
Sintering is the heating and fusing of small particles resulting in a hard bonded material block.
The un-sintered powder supports the part as the layers are sintered.
SLS

27. Fused-deposition modeling (FDM) process
Filament
Spool
Heater
Drive Wheels
Table
Fused Part
Head motion
Table motion
Head
Molten filament
FDM, PDF

28. (Courtesy of Stratasys Corporation)
FDM – Stratasys 3000
(Courtesy of Stratasys Corporation)

29. Cowling (courtesy of Stratasys)

30. Trike (courtesy of Stratasys)

31. Fused Deposition Modeling (FDM)
Parts can be made from
high strength ABS plastic, impact resistant ABS,
investment casting wax, and an
elastomer.
Prototype parts are well suited for form and fit testing.
Some function testing

32. 3-D Inkjet prototyping
Glue-like binder selectively “printed” onto a layer of dry powder, layer by layer, which dries into a solid prototype.
Similar process uses a print head to deposit a thermoplastic material, layer by layer.
Quick and inexpensive
The processes work well as concept modelers.
Prototypes have limited dimensional tolerances
Somewhat fragile unless coated with a hardener
Prototypes made with this process are typically not function tested.
3DP

33. Z-Corporaton Z406 (“Inkjet”)
(Courtesy of Z-Corporation)

34. Chrome Wheel (courtesy of Z-Corporation)

35. Electrolux (courtesy of Z-Corporation)

36. Baby seat (courtesy of Z-Corporation)

37. 3-D Inkjet Manifold
(courtesy of Z-Corporation)

38. Laminated Object Manufacturing (LOM)
Laminating thin layers of paper, polymer or sheet steel, which have been cut using a numerically controlled laser.
LOM prototypes can be sanded to reduce jagged edges, but are not able to be function tested such as for stress or strain due to the allotropic material properties of the laminate.
LOM

39. Service Bureaus
Product manufacturer s the solid model part file to the service bureau, typically as an *.STL file.
The bureau uses its software to convert the *.STL file to a “sliced” file format specific to the selected prototyping hardware (i.e. FDM, SLA, SLS, LOM),
Part is fabricated along with any duplicates.
Part(s) may then be overnight-mailed to the product manufacturer.

40. Which Prototyping Method is Best: Traditional or Rapid?
Shape generating compatibility – Can the material be formed into the needed geometric features to adequately represent the part?
Function testing validity – Are the material properties representative, or scalable such that the part when reduced (or expanded) in size, can be validly tested?
Fabrication costs – Will the prototype costs for materials and labor be acceptable?
Fabrication time – How long will it take to fabricate the original and one or more duplicates?

41. Engineering Tests Mechanical / modes of failure Manufacturability
Operation / maintenance
Safety
Environmental
Engineering tests ≠ Experiments
(Experiments validate phenomena)

42. Engineering Tests
Briefly describe the difference between engineering tests and scientific experiments.
Scientific experiments establish relationships between causes and effects. That is, they determine scientific principles. For example, a force exerted on a mass causes it to accelerate (effect).
Engineering tests validate the application of principles given specific assumptions. For example, will a given sized motor produce enough torque given the frictional losses in the system.

43. 1. Mechanical modes of failure
static strength
fatigue
deflection/stiffness
creep, impact
vibration
thermal/heat transfer/fluid
energy consumption / production
friction (i.e. too much, too little)
wear
lubrication
corrosion
life, reliability

44. 2. Manufacturability concerns
process compatibility/precision
process technology readiness
raw material quality
assembly

45. 3. Operation and or maintenance concerns
styling/aesthetics
ergonomics
maintenance
repairs

46. 4. Safety concerns risk to user, products liability
risk to consumer /society
safety codes, standards (UL, NHTSA)
risk to production worker (e.g. OSHA)
National Highway Traffic Safety Administration (NHTSA)
Underwriters Laboratories Inc. (UL)
Occupational Safety and Health Administration (OSHA)

47. 5. Environmental protection concerns
air quality, noise
water - quality, quantity
solid waste – hazardous materials
radioactivity – fallout

48. Test plans – written and approved
Objectives –
list of items (parts, systems, models) to be tested
purposes for which the tests are being conducted
Workscope – narrative description:
type of tests,
test descriptions/procedures,
experimental setup,
experimental controls,
design of experiments test matrix, and
list of deliverables.
Budget
Schedule
Examples: 1, 2, 3

49. Summary
Companies build and test prototypes to ensure form, fit and function.
Product development tests include: product-concept, proof-of-concept, virtual, alpha, beta, and preproduction.
Prototypes can be built using traditional and rapid prototyping methods and materials.
Rapid prototyping methods include NC/CNC, SLA, FDM, LOM, SLS, and 3-D Inkjet printing.
Rapid prototyping takes advantage of CAD
Part and product testing can include tests for: mechanical modes of failure, manufacturability, user operation & maintenance, safety and environmental protection.
Product development often requires the preparation and completion of a detailed test plan.