SafeSource: Formal Design
Review
Team 3:
Robin Davis
Meryl del Rosario
Joanna Natsios
Paul Saindon
Product Design Specifications
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Bucket
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20 L capacity
Head dimple on bottom
Stackable for shipping
Spigot
Lid
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4 in. fill port with cap
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General
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Durable
Thermoformable material
Inexpensive
Thermoforming Process
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Heat thermoforming
apparatus
Insert mold and plastic
Heat plastic
Turn on vacuum and push
mold up into plastic
Cool plastic-mold slightly
Remove mold
Allow for complete plastic
cooling
Material Selection- Thermoforming
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Thermoplastics
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Amorphous
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Lower thermoforming temperature
Forgiving of temperature variations
Forms well with wooden molds
Creeps over time under load
Crystalline
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No creep, but warpage
Totally stiff until softening temperature is reached
Must be formed around aluminum mold
Our Materials
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Requirements:
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Polycarbonate (Lexan 9440)
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GE Polymershapes
UHMW Polyethylene
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food grade
UV resistant
cheap
clear/translucent
no reaction with kerosene or NaOH
McMaster-Carr
ABS
Property Comparison
http://www.mcmaster.com/
Design Limitations
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Constrained
thermoforming size
Draw ratio
Avoiding undercuts
Preventing webbing
Bucket needs to be 20L
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14”x11”x8”
Thermoforming Experience
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Wooden mold for lid
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Made from scrap using
simple tools
Thermoformed
successfully
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Nearly fits bucket
Observations: Warpage
and lack of undercut
Revisions and Returns
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A second mold was
designed to correct the
problems of the first
Fill port added
Triangular feet to
improve undercutting
Our design process will
be iterative!
Top View
Bottom View
Mold Design: Bucket
Mold Design: Lid
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Wood for easy creation
Triangular shape to improve removability
from mold
Undercut and feet to provide snap for
attaching to bucket.
Biggest challenge: design of fill port cap
Looking Towards Production
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Would want a Steel or Aluminum Mold with
cooling channels
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Increased consistency of parts
Increased rate of production
Longer mold life
Better thermal properties
Develop jig cutting technique
Compressive Testing of 3DP Material
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Mold must withstand 15psi
9 2-inch cubes
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4 cubes w/ new glue,
5 cubes w/ old glue
Tested each direction 3X
Results
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New
Glue
σy (psi)
Old σy (psi)
Glue
X
824
X
609
Y
567
Y
488
Z
534
Z
396
AVG
641
AVG 498
Compressive strength greatly exceeds 15psi
Strongest in X-direction, weakest in Z (binding) direction
Stronger when infiltrated w/ new glue
Future Testing
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3-point Beam Bending
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ASTM for a ceramic
 0.25” thick
 1.5” long
3D print specimens in
different orientations
Printer problems
Further Investigation
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Deformation Mapping
Shrinkage Analysis
Impact Tests
Drop Strength Analysis (ANSYS or ASTM)
Non-Newtonian Flow
Design Variables
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Plastic thickness
Tapering
Snap mechanism
Ribbing
Project Timeline
Feb 12
Mar 1
Mar 15
Apr 2
Apr 15
May 6
1
2
3
4
5
6
7
8
9
10
1. Learn SolidWorks and ANSYS
6. Design mold of interlocking parts
2. Create compressive elements on
SolidWorks
7. Print 3D scale models of bucket and lid
3. 3D print compressive elements
4. Conduct compressive strength tests
and 3pt beam bending tests
5. Determine physical limits of mold
geometry
8. Thermoform scale prototypes with
various materials
9. Choose material for final bucket and lid
10. Make full-sized bucket and lid