Design Review
Group members:
Ed Barnard
Lizzie Hager
Jenny Lichter
Kevin McComber
3-11-04
Overview
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Goal and Processing Method
Ceramic Preform
Pressure Vessel Calculations
Prototype Mold Design
Expected and Threshold Pressures
Infiltration
ASME Standards for Hammers
Methods of Characterization
Risks
Goal
The goal of our project is to
manufacture a light-weight, high
fracture toughness hammer using
metal matrix composites.
Halstead
Centrifugal Casting Process
Ceramic Preform
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Compression packing
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Sintering
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May form connected ceramic matrix which could
require post processing
3D printing
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May not produce uniform preform
Can be improved through agitation
May be time intensive
Binder
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Must be able to be burnt out
Numerical Simulations
Monte Carlo Simulations
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Were considered to model packing density of
ceramic powders
Assume spherical particles
Our particles are not spherical
Pressure Vessel Calculations
Pmax 
Material
Brass
Stainless steel
Aluminum
Graphite
 UTS  r  ri 
2
o
2
o
2


2 
S.F .  r  ri 
Pmax = 2200 psi = 150 atm
S. F. : safety factor = 2
ri : inner radius = 1.00 inch
σUTS (ksi)
radiusouter
< σUTS >
radiusouter
(σUTS)min
30-90
1.08
1.16
60-150
1.04
1.08
45-80
1.07
1.10
7-10
1.77
2.09
Wannasin
Pressure Vessel Calc. Ct’d
Current design: Aluminum 6061
inner radius of 0.75 inches
Material
Aluminum
σUTS (ksi)
radiusouter
radiusouter
< σUTS >
(σUTS)min
45-80
0.80
0.82
outer radius of 1.00 inches
Prototype Mold
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Two-piece mold
Conical shape to aid in the release
Swagelok connector to runner
1.0
.5
.75
5.5
2.0
1.5
1.75
1.0
3.0
Release from mold
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Boron Nitride Spray Coating
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Graphite powder
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Breakaway ceramic
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TiC – small particle size
Need a binder
Expected Pressures
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Moment of inertia calculations
Assumption of constant angular energy
I1 ω12
=
I2 ω22
ω1 = 2200 rpm, ω2 = 1250 rpm
Pressure calculations:
P = ( ½ ) * (ρω2) * (z22 – z12)
Currently: 2200 psi or 150 atm
New design: 710 psi or 50 atm
Wannasin
Threshold Pressures
Particulate
SiC
Size
(microns)
7 - 155
Threshold Pressure
(atm)
2 - 22
Al2O3
5 - 20
8 - 11
B4C
9
3-4
TiC
30
5-6
Based on aluminum infiltration
Generally threshold pressure decreases
with increasing particle size
Infiltration
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Larger particles necessary
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Previously used particles a few microns in size
Future Particles (already purchased)
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Boron Carbide 100 grit (106-150 microns)
Silicon Carbide 120 grit (90-125 microns)
Silicon Carbide 36 grit (600-850 microns)
Safety Requirements (ASME):
Design Parameters
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Chamfer striking face
45 degrees with length
equal to 1/10 of bell (to
prevent chipping)
Striking face must be
flat or convex
No unnecessary sharp
edges, points or surface
roughness
Chamfer
Bell
Striking Face
Halstead
Safety Requirements (ASME):
Mechanical Properties
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Hardness Test
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Striking face hardness: 40-60 HRC
Hardness must be maintained at least .75 in.
into bell
Striking Test
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Average person (160-180 lbs) must strike steel
(of hardness 92-105 HRB) 20 times without
causing damage
Safety Requirements (ASME):
Mechanical Properties Cont.
Assembled Parts Tests
(calculated for hammerhead of 300-350 grams)
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Static Test
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556 Newtons or 125 lbs.
Tensile Test (for non-wedged assemblies)
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3340 Newtons or 750 lbs.
Methods of Characterization
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SEM
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Estimate ceramic volume fraction
Possible defects – microvoid formation
Incomplete infiltration
Rockwell Hardness
Impact tests
Tensile and compression tests
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Plastic deformation
Risks
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Particle size leads to incomplete infiltration
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Reduce mold weight
Increase particle size
Different preform production method
Mold leaks
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O-ring system
Use outer tube to hold molds
Risks, Ct’d
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Part cannot be removed
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Low hardness
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Use stronger mold release spray
Change angle of mold
Choose different ceramic particles with better
wettability with respect to metal
Use multiple types of ceramic particles
Air pockets
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Design an evacuation system
Projected Work Schedule
2/5 2/12 2/19 2/26 3/4 3/11 3/18 3/25 4/1 4/8 4/15 4/22 4/29 5/6 5/13
Materials
Metal choice
Ceramics choice
Part production
CAD
Alum. machined mold
Ceramic preform
Volume fraction
Size distribution
Time Permitting
"
Final testing
CODE:
Task
Sub-task
Gradation
Testing
Works Cited
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Halstead, Gary. “Pictures from Dictionaire Paisonné du Mobilier Français.” Accessed 24
February 2004. Medieval and Renaissance Woodworking. 2003.
<http://www.medievalwoodworking.com/vld_tools.htm >.
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Wannasin, Jessada. PhD Thesis. March 2004.