Design & Manufacturing of Materials
2nd
6 Lectures, Trinity Term 2003
year Materials: Engineering Applications of Materials
Dr Ian Stone (5 lectures) & Dr Paul Butler (1 lecture)
Synopsis
Product design:
Product development; design core; market analysis and
competitive benchmarking; product design specification;
concept design; detail design.
Materials selection:
Development of materials performance indices with and without
shape, materials selection maps, case studies of materials
selection: oars, springs, pressure vessels, etc.; selection with
multiple constraints.
Process selection:
Process selection charts, case studies of a fan, ceramic valve;
process costs and cost breakdown.
Manufacturing industry:
Plant location; plant layout; critical path analysis; production
scheduling; materials requirement planning; Just in Time
management.
Metal forming in the packaging
industry:
Forming limit diagrams; R-curves; forming processes (e.g. deep
drawing); Strain path analysis.
Further Reading
S. Pugh
Total Design, Addison-Wesley, 1991
(56PUG)
M.F. Ashby & D.R.H. Jones
Engineering Materials 1, Pergamon, 1980
(50ASH/1)
M.F. Ashby & D.R.H. Jones
Engineering Materials 2, Pergamon, 1986
(50ASH/2)
M.F. Ashby
Materials Selection in Mechanical Design,
Butterworth & Heinemann, 1992 (56ASH/1)
B. Derby, D.A. Hills & C.
Ruiz
Materials for Engineering, Wiley 1992
(50DER)
E.J. Anderson
The Management of Manufacturing,
Addison-Wesley, 1994 (56AND)
Product Development
Product Development Team
Marketing
Manufacturing
Design
Provides market assessment
Identifies market opportunities
Assesses production process
Assesses manufacturing costs and quality
Defines product form and function
Engineering Design
Industrial Design
Product Development Type
Development time
Development cost
Development type
1-10 years depending on product
$100k-$5B depending on product
Generic/Market pull
Technology push
Technology platform
Process limited
Customised
Company Innovation
Large companies vs SMEs (small and medium size enterprises)
Product Development Team
Manufacturing
Engineer
Finance
Marketing
Professional
Purchasing
Specialist
TEAM
LEADER
Sales
Legal
Industrial
Designer
Electronics
Designer
Mechanical
Designer
Extended Team
(including suppliers)
Product Development Type
Description
Generic
(Market Pull)
Technology
Push
Platform
Products
Process
Intensive
Customization
The firm begins
with a market
opportunity, then
finds an
appropriate
technology to
meet customer
needs.
The firm begins
with a new
technology, then
finds an
appropriate
market.
The firm assumes
that the new
product will be
built around the
same
technological
subsystem as an
existing product.
Characteristics of
the product are
constrained by the
production
process.
New products are
slight variations of
existing
configurations.
Additional initial
activity of
matching
technology and
market.
Concept
development
assumes a
technology
platform.
Both process and
product must be
developed
together from the
very beginning, or
an existing
production
process must be
specified from the
beginning.
Similarity of
projects allows for
a highly structured
development
process.
Snack foods,
cereal, chemicals,
semiconductors.
Switches, motors,
batteries,
containers.
Distinctions
with respect
to the generic
process
Concept
development
assumes a given
technology.
Examples
Sporting goods,
furniture, tools.
Gore-Tex
rainwear, Tyvek
envelopes.
Consumer
electronics,
computers,
printers.
Development is
almost like a
production
process.
Product Development Examples
Stanley Tools
Jobmaster
screwdriver
Rollerblade
Bravoblade InLine Skates
Hewlett-Packard
DeskJet 500
Printer
Chrysler
Concorde Car
Boeing 777
Aeroplane
Annual production
volume
100,000
units/year
100,000
units/year
1.5 million
units/year
250,000
units/year
50
units/year
Sales lifetime
40 years
3 years
3 years
6 years
30 years
Sales price
$3
$200
$365
$19,000
$130 million
Number of unique
components
3
35
200
10,000
130,000
Development time
1 year
2 years
1.5 years
3.5 years
4.5 years
Internal
development team
size
3
people
5
people
100
people
850
people
6,800
People
External
development team
size
3
people
10
people
100
people
1400
people
10,000
People
Development cost
$150,000
$750,000
$50 million
$1 billion
$3 billion
Production
investment
$150,000
$1 million
$25 million
$600 million
$3 billion
Innovation in Firms
1945-9
(%)
1950-4
(%)
1955-9
(%)
1960-4
(%)
1965-9
(%)
1970-4
(%)
1975-80
(%)
Total
(%)
1-199
16
12
11
11
13
15
17
14
200-499
9
6
8
6
7
9
7
7
500-999
3
2
7
5
5
4
3
4
1,000-9,999
36
36
25
27
23
17
14
23
10,000 and
over
36
44
50
51
52
55
59
52
Total
100
100
100
100
100
100
100
100
Number of
Innovations
94
191
274
405
467
401
461
2293
Number of
employees
Total Design
is a systematic activity:
Identification of the market need → sale of product to
meet that need.
Product, Process, People, Organization, etc.
Design Core
Market Analysis
Specification
Concept Design
Detailed Design
Manufacturing
Sales
Product Design Specification (PDS)
Market
Assessment
Specification
Concept
Design
Detail
Design
Manufacture
Envelopes all stages of the design core
Sell
THE DESIGN CORE
The Design Core
Market
Assessment
Specification
MARKET
ASSESSMENT
Concept
Design
Interviews, Questionnaires, Focus
Groups
Intellectual Property and Literature
Searches
Competitive Benchmarking
parametric analysis, needs matrix
Detail
Design
Manufacture
Sell
Market Analysis: Example 1
Tristar 333
A rough terrain
telescopic handler
with parallel lift
Market Analysis: Tristar 333
Market Analysis: Example 2
Microm 160
A microscope
manipulator for
opthalmology







Coaxial illumination
2
Moto. vert. course movement
3
Moto. vert. fine movement
4
X-Y attachment



5
Motorized zoom (microscope)



6
Motorized zoom (arm)
7
Auto. step magnification





8
Hand switch controls





9
Mouth switch
10
Foot switch
11
Counterbalanced by weight
12
Counterbalanced by spring
13
Energized locking
14
Friction locking
15
Stepped locking
16
Rotation free around stand

ZEISS E.M. CEILING

1
KEELER K-380 FW
AMSCO, AMSCOPE
WECK (CEILING)
WECK 10108

WILD MS-F

WILD MS-B
WILD MS-C
ZEISS UNIVERSAL
Feature and function
ZEISS (J) SLIT LA.
No.
COOPER VISION
Make and Model
Graphical
representation of
percentage
%
xxxxxx
54
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xx
18
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100
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82
0
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100
x
9
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54
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18
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82
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100
MATRIX ANALYSIS

20
Tilt of microscope attachment

21
Rotation of micros. attachm.

22
Yaw of micros. attachment
23
Connection facil. for attachm.
24
Stand levelling facilities
25
Stand braking facilities

26
Fibre optic illumination

27
Down limiting stop

28

























ZEISS E.M. CEILING
Vertical mov. of the arm

KEELER K-380 FW
19

AMSCO, AMSCOPE


WECK (CEILING)
Course mov. in horiz. plane

WECK 10108
18
WILD MS-F
Vert. course mov. of assembly
WILD MS-B

17
WILD MS-C
ZEISS UNIVERSAL
Feature and function
ZEISS (J) SLIT LA.
No.
COOPER VISION
Make and Model


xxxxxx
55



xxxxxxxxxxx
100
xxxxxx
55

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100

xxxxxx
55
xxxx
35
xxxxxxxxxx
91
x
9
xxxxxx
55

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64

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45
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





Manual step magnification


29
Slit illumination


30
Manual zoom
31
Horiz. mov. on plane of arms
32
Floor mounted











%



Graphical
representation of
percentage



xxxxxxxx
73

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
xxxxxxx
64
0
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63
MATRIX ANALYSIS cont’d
The Design Core
Market
Assessment
SPECIFICATION
Specification
Product Design Specification (PDS)
Develop Specification (8 stages)
1. Construct customer needs matrix
2. Develop performance measures
3. Cross correlate (needs-measures matrix)
4. Construct competitive benchmark chart to
assess market position (based on customer
needs and performance measures)
5. Define an initial set of target specifications
6. Carry out engineering design analysis to assess
technical feasibility
7. Develop a bill of materials for initial cost
assessment
8. Redefine the set of specifications
Concept
Design
Detail
Design
Manufacture
Sell
Product Design Specification (PDS)
Environment
Patents
Shelf life
Packing
Testing
Competition
Safety
Weight
Legal
Maintenance
Quantity
Materials
Politics
Ergonomics
Plant
Aesthetics
Disposal
DESIGN
CORE
Installation
Shipping
Size
Service life
Standards
Performance
Processes
Customer
Quality
assurance
Timescale
Storage
Element to be considered:
Partial PDS
In
Environment
Patents
Out
Shelf life
Packing
Testing
Competition
Safety
Weight
Legal
Maintenance
Quantity
Materials
Politics
Ergonomics
Plant
Aesthetics
Disposal
DESIGN
CORE
Installation
Shipping
Size
Service life
Standards
Performance
Processes
Customer
Quality
assurance
Timescale
Storage
For individual
components, subassemblies, different
stages of the design
core.
Design Specification: Stage 1
No.
Need
Importance
(1-5)
1
The product must …..
4
2
The product is …..
5
3
The product allows …..
3
4
The product can …..
1
5
The product lasts …..
5
etc.
etc.
etc.
Stage 1: Customer needs matrix
Design Specification: Stage 2
Metric
No.
Need
Nos.
A
1,2
B
Metric
Importance
(1-5)
Units
Cost
5
£
2
Total mass
5
kg
C
3
Compatibility
3
list
D
4
Assembly time
1
s
E
5
Fatigue life
5
cycles
etc.
etc.
etc.
etc.
etc.
Stage 2: Develop performance measures
Design Specification: Stage 3
A
B
C
D
E
Cost
Total mass
Compatibility
Assembly time
Fatigue life
METRIC
NEED
1
The product must …..

2
The product is …..

3
The product allows …..
4
The product can …..
5
The product lasts …..




Stage 3: Cross correlate (needs-measures matrix)
Design Specification: Stage 4
No.
Need
Importance
(1-5)
Comp
1
Comp
2
Comp
3
Comp
4
1
The product must …..
4
x
xxx
xx
xxxx
2
The product is …..
5
xxx
xxxx
x
xxx
3
The product allows …..
3
xx
xx
xxxx
x
4
The product can …..
1
xxxxx
x
x
xx
5
The product lasts …..
5
xx
xxx
xxx
xxxx
etc.
etc.
etc.
etc.
etc.
etc.
etc.
Stage 4: Construct competitive benchmark chart to
assess market position (based on customer needs)
Design Specification: Stage 4 cont’d
Metric
No.
Need
Nos.
A
1,2
B
Metric
Importance
(1-5)
Units
Comp
1
Comp
2
Comp
3
Comp
4
Cost
5
£
60
80
70
90
2
Total mass
5
kg
2.3
2.2
2.5
2.3
C
3
Compatibility
3
list
w,x
w,y
w,x,y,z
w
D
4
Assembly time
1
s
70
90
90
85
E
5
Fatigue life
5
cycles
22k
23k
23k
24k
etc.
etc.
etc.
etc.
etc.
etc.
etc.
etc.
etc.
Stage 4: Construct competitive benchmark chart to
assess market position (based on performance
measures)
Design Specification: Stage 5
Metric
No.
Need
Nos.
A
1,2
B
Metric
Importance
(1-5)
Units
Marginal
Value
Ideal
Value
Cost
5
£
<80
<60
2
Total mass
5
kg
<2.4
<2.2
C
3
Compatibility
3
list
w
w,x,y,z
D
4
Assembly time
1
s
<90
<70
E
5
Fatigue life
5
cycles
>23k
>24k
etc.
etc.
etc.
etc.
etc.
etc.
etc.
Stage 5: Initial set of target specifications
Design Specification: Stage 6
Geometry
Materials Properties
Fastening Methods
Surface finish
DESIGN MODELS
(Model Inputs)
Fatigue Model
Cycles to Failure
METRICS
(Model Outputs)
Stage 6: Engineering design analysis to assess
technical feasibility
Design Specification: Stage 7
Component
Handle
Subframe
Housing
Seal
Bolt
Nut
Assembly @ £10/hr
Overhead @25% of direct cost
TOTAL
Qty/Part
High
(£ ea.)
Low
(£ ea.)
High
Total
(£/Part)
Low
Total
(£/Part)
2
1
1
1
4
4
5.00
35.00
25.00
1.50
0.30
0.15
6 mins
3.50
28.00
18.00
1.00
0.20
0.10
4 mins
10.00
35.00
25.00
1.50
1.20
0.60
1.00
18.58
7.00
28.00
18.00
1.00
0.80
0.40
0.67
13.97
92.88
69.84
Stage 7: Develop a bill of materials for initial cost
assessment
Design Specification: Stage 8
Metric
No.
Need
Nos.
A
1,2
B
Metric
Importance
(1-5)
Units
Value
Cost
5
£
<70
2
Total mass
5
kg
<2.3
C
3
Compatibility
3
list
w,x,y
D
4
Assembly time
1
s
<80
E
5
Fatigue life
5
cycles
>24k
etc.
etc.
etc.
etc.
etc.
etc.
Stage 8: Refined set of specifications
Example
A Mountain Bike
Suspension Fork
Stage 1: Customer
needs matrix
No.
Need
Importance
1
The suspension
reduces vibration to the hands.
3
2
The suspension
allows easy traversal of slow, difficult terrain.
2
3
The suspension
enables high-speed descents on bumpy trails.
5
4
The suspension
allows sensitivity adjustment.
3
5
The suspension
preserves the steering characteristics of the bike.
4
6
The suspension
remains rigid during hard cornering
4
7
The suspension
is lightweight.
4
8
The suspension
provides stiff mounting points for the brakes.
2
9
The suspension
fits a wide variety of bikes, wheels and tyres.
5
10
The suspension
is easy to install.
1
11
The suspension
works with mudguards.
1
12
The suspension
instils pride.
5
13
The suspension
is affordable for an amateur enthusiast.
5
14
The suspension
is not contaminated by water.
5
15
The suspension
is not contaminated by mud and dirt.
5
16
The suspension
can be easily accessed for maintenance.
3
17
The suspension
allows easy replacement of worn parts.
1
18
The suspension
can be maintained with readily available tools.
3
19
The suspension
lasts a long time.
5
20
The suspension
is safe in a crash.
5
Metric
No.
Need
Nos.
A
1,3
B
Metric
Imp.
Units
Attenuation from dropout to handlebar at 10 Hz
3
dB
2,6
Spring preload
3
N
C
1,3
Maximum value from the Monster test
5
g
D
1,3
Minimum descent time on test track
5
s
E
4
Damping coefficient adjustment range
3
Ns/m
F
5
Maximum travel (26 in. wheel)
3
mm
G
5
Rake offset
3
mm
H
6
Lateral stiffness at the tip
3
kN/m
I
7
Total mass
4
kg
J
8
Lateral stiffness at brake pivots
2
kN/m
K
9
Headset sizes
5
in
L
9
Steertube length
5
mm
M
9
Wheel sizes
5
list
Stage 2: Develop performance measures
Metric
No.
Need
Nos.
N
9
O
Metric
Imp.
Units
Maximum tyre width
5
in
10
Time to assemble to frame
1
s
P
11
Mudguard compatibility
1
list
Q
12
Instils pride
5
subj.
R
13
Unit manufacturing cost
5
US$
S
14
Time in spray chamber without water entry
5
s
T
15
Cycles in mud chamber without contamination
5
k-cycles
U
16,17
Time to disassemble/assemble for maintenance
3
s
V
17,18
Special tools required for maintenance
3
list
W
19
UV test duration to degrade rubber parts
5
hours
X
19
Monster test cycles to failure
5
cycles
Y
20
Japan Industrial Standards test
5
pass/fail
Z
20
Bending strength (frontal loading)
5
kN
Stage 2: Develop performance measures (cont’d)
METRIC
A
1


5
7
8
9
NEED
10
11
12
13
14
15
D




E
F
G


H
I
J
K
L
M
N




O
P
Q
R
S
T
U



Y
Z









17

20
X


19
W

16
18
V

4
6
C

2
3
B


Stage 3: Cross correlate (needs-measures matrix)
ST
Tritrack
Maniray
2
Rox
Tahx
Quadra
Rox
Tahx
Ti 21
Tonka
Pro
Gunhill
Head
Shox
No.
Need
Imp.
1
reduces vibration to the hands.
3
x
xxxx
xx
xxxxx
xx
xxx
2
allows easy traversal of slow, difficult terrain.
2
xx
xxxx
xxx
xxxxx
xxx
xxxxx
3
enables high-speed descents on bumpy trails.
5
x
xxxxx
xx
xxxxx
xx
xxx
4
allows sensitivity adjustment.
3
x
xxxx
xx
xxxxx
xx
xxx
5
preserves the steering characteristics of the bike.
4
xxxx
xx
x
xx
xxxxxxxx
6
remains rigid during hard cornering
4
x
xxx
x
xxxxx
x
xxxxx
7
is lightweight.
4
x
xxx
x
xxx
xxxx
xxxxx
8
provides stiff mounting points for the brakes.
2
x
xxxx
xxx
xxx
xxxxxxx
9
fits a wide variety of bikes, wheels and tyres.
5
xxxx
xxxxx
xxx
xxxxx
xxx
x
10
is easy to install.
1
xxxx
xxxxx
xxxx
xxxx
xxxxx
x
11
works with mudguards.
1
xxx
x
x
x
x
xxxxx
12
instils pride.
5
x
xxxx
xxx
xxxxx
xxx
xxxxx
13
is affordable for an amateur enthusiast.
5
xxxxx
x
xxx
x
xxx
xx
14
is not contaminated by water.
5
x
xxx
xxxx
xxxx
xx
xxxxx
15
is not contaminated by mud and dirt.
5
x
xxx
x
xxxx
xx
xxxxx
16
can be easily accessed for maintenance.
3
xxxx
xxxxx
xxxx
xxxx
xxxxx
x
17
allows easy replacement of worn parts.
1
xxxx
xxxxx
xxxx
xxxx
xxxxx
x
18
can be maintained with readily available tools.
3
xxxxx
xxxxx
xxxxx
xxxxx
xx
x
19
lasts a long time.
5
xxxxx
xxxxx
xxxxx
xxx
xxxxx
x
20
is safe in a crash.
5
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
Stage 4: Construct competitive benchmark chart to
assess market position (based on customer needs)
Specification: A Mountain Bike Suspension Fork
Metric
No.
Need
Nos.
A
1,3
B
Metric
Imp
Units
ST
Tritrack
Maniray
2
Rox
Tahx
Quadra
Rox
Tahx
Ti 21
Tonka
Pro
Gunhill
Head
Shox
Attenuation from dropout to
handlebar at 10 Hz
3
dB
8
15
10
15
9
13
2,6
Spring preload
3
N
550
760
500
710
480
680
C
1,3
Maximum value from the Monster
test
5
g
3.6
3.2
3.7
3.3
l.7
3.4
D
1,3
Minimum descent time on test track
5
s
13
11.3
12.6
11.2
13.2
11
E
4
Damping coefficient adjustment
range
3
Ns/m
0
0
0
200
0
0
F
5
Maximum travel (26 in. wheel)
3
mm
28
48
43
46
33
38
G
5
Rake offset
3
mm
41.5
39
38
38
43.2
39
H
6
Lateral stiffness at the tip
3
kN/m
59
110
85
85
65
130
I
7
Total mass
4
kg
1.409
1.385
1.409
1.364
1.222
1.100
J
8
Lateral stiffness at brake pivots
2
kN/m
295
550
425
425
325
650
K
9
Headset sizes
5
in
1.000
1.125
1.000
1.125
1.250
1.000
1.125
1.000
1.125
1.250
1.000
1.125
N/A
L
9
Steertube length
5
mm
150
180
210
230
255
140
165
190
215
150
170
190
210
150
170
190
210
230
150
190
210
220
N/A
Stage 4: Construct competitive benchmark chart to assess
market position (based on performance measures)
Metric
No.
Need
Nos.
M
9
N
Metric
Imp
Units
ST
Tritrack
Maniray
2
Rox
Tahx
Quadra
26 in
26 in
Rox
Tahx
Ti 21
Wheel sizes
5
list
26 in
9
Maximum tyre width
5
in
1.5
1.75
1.5
1.75
1.5
1.5
O
10
Time to assemble to frame
1
s
35
35
45
45
35
85
P
11
Mudguard compatibility
1
list
Zefal
none
none
none
none
all
Q
12
Instils pride
5
subj.
1
4
3
5
3
5
R
13
Unit manufacturing cost
5
US$
65
105
85
115
80
100
S
14
Time in spray chamber without
water entry
5
s
1300
2900
>3600
>3600
2300
>3600
T
15
Cycles in mud chamber without
contamination
5
k-cycles
15
19
15
25
18
35
U
16,17
Time to disassemble/assemble for
maintenance
3
s
160
245
215
245
200
425
V
17,18
Special tools required for
maintenance
3
list
hex
hex
hex
hex
long hex
hex, pin
wrench
W
19
UV test duration to degrade rubber
parts
5
hours
>400
250
>400
>400
>400
250
X
19
Monster test cycles to failure
5
cycles
>500k
>500k
>500k
480k
>500k
330k
Y
20
Japan Industrial Standards test
5
pass/fail
pass
pass
pass
pass
pass
pass
Z
20
Bending strength (frontal loading)
5
kN
5.5
8.9
7.5
7.5
6.2
10.2
26 in
700C
Tonka
Pro
26 in
Gunhill
Head
Shox
26 in
Stage 4: Construct competitive benchmark chart to assess
market position (based on performance measures) (cont’d)
Metric
No.
Need
Nos.
A
1,3
B
Metric
Imp
Units
Marginal
Value
Ideal Value
Attenuation from dropout to handlebar at 10 Hz
3
dB
>10
>15
2,6
Spring preload
3
N
480-800
650-750
C
1,3
Maximum value from the Monster test
5
g
<3.5
<3.2
D
1,3
Minimum descent time on test track
5
s
<13.0
<11.0
E
4
Damping coefficient adjustment range
3
Ns/m
0
>200
F
5
Maximum travel (26 in. wheel)
3
mm
35-50
45
G
5
Rake offset
3
mm
37-45
38
H
6
Lateral stiffness at the tip
3
kN/m
>65
>130
I
7
Total mass
4
kg
<1.4
<1.1
J
8
Lateral stiffness at brake pivots
2
kN/m
>325
>650
K
9
Headset sizes
5
in
1.000
1.125
1.000
1.125
1.250
L
9
Steertube length
5
mm
150
170
190
210
150
170
190
210
230
M
9
Wheel sizes
5
list
26 in
26 in
700C
Stage 5: Initial set of target specifications
Metric
No.
Need
Nos.
N
9
O
Metric
Imp
Units
Marginal
Value
Ideal Value
Maximum tyre width
5
in
>1.5
>1.75
10
Time to assemble to frame
1
s
<60
<35
P
11
Mudguard compatibility
1
list
none
all
Q
12
Instils pride
5
subj.
>3
>5
R
13
Unit manufacturing cost
5
US$
<85
<65
S
14
Time in spray chamber without water entry
5
s
>2300
>3600
T
15
Cycles in mud chamber without contamination
5
k-cycles
>15
>35
U
16,17
Time to disassemble/assemble for maintenance
3
s
<300
<160
V
17,18
Special tools required for maintenance
3
list
hex
hex
W
19
UV test duration to degrade rubber parts
5
hours
>250
>450
X
19
Monster test cycles to failure
5
cycles
>300k
>500k
Y
20
Japan Industrial Standards test
5
pass/fail
pass
pass
Z
20
Bending strength (frontal loading)
5
kN
>6
>10
Stage 5: Initial set of target specifications (cont’d)
Assess Technical Feasibility
Suspended Mass
Unsprung Mass
Orifice Diameter
Spring Constant
Oil Viscosity
Dynamic Model of
Suspension Performance
(Analytical)
Support Geometry
Materials Properties
Tube Geometry
Mounting Points
Static Model of
Brake Mounting Stiffness
(Analytical)
Lateral Stiffness
Fatigue Model of
Suspension Durability
(Physical)
Cycles to Failure
Fork Geometry
Materials Properties
Fastening Methods
Suspension Geometry
DESIGN MODELS
(Model Inputs)
Attentuation at 10 Hz
Estimated Monster g’s
METRICS
(Model Outputs)
Stage 6: Engineering design analysis to assess
technical feasibility
Component
Steer tube
Crown
Boot
Lower tube
Lower tube top cover
Main lip seal
Slide bushing
Slide bushing spacer
Lower tube plug
Upper tube
Upper tube top cap
Upper tube adjustment knob
Adjustment shaft
Spring
Upper tube orifice cap
Orifice springs
Brake studs
Brake brace bolt
Brake brace
Oil (litres)
Misc. snap rings, o-rings
Decals
Assembly at $20/hr
Overhead at 25% of direct cost
TOTAL
Qty/fork
High
($ ea.)
Low
($ ea.)
High Total
($/fork)
Low Total
($/fork)
1
1
2
2
2
2
4
2
2
2
2
2
2
2
1
4
2
2
1
0.1
10
4
2.50
4.00
1.00
3.00
2.00
1.50
0.20
0.50
0.50
5.50
3.00
2.00
4.00
3.00
3.00
0.50
0.40
0.25
5.00
2.50
0.15
0.25
30 min
2.00
3.00
0.75
2.00
1.50
1.40
0.18
0.40
0.35
4.00
2.50
1.75
3.00
2.50
2.25
0.40
0.35
0.20
3.50
2.00
0.10
0.15
20 min
2.50
4.00
2.00
6.00
4.00
3.00
0.80
1.00
1.00
11.00
6.00
4.00
8.00
6.00
3.00
2.00
0.80
0.50
5.00
0.25
1.50
1.00
10.00
20.84
$104.19
2.00
3.00
1.50
4.00
3.00
2.80
0.72
0.80
0.70
8.00
5.00
3.50
6.00
5.00
2.25
1.60
0.70
0.40
3.50
0.20
1.00
0.60
6.67
15.74
$78.68
Stage 7: Develop a bill of materials for initial cost assessment
Metric
No.
Metric
Units
Value
A
Attenuation from dropout to handlebar at 10 Hz
dB
>12
B
Spring preload
N
600-650
C
Maximum value from the Monster test
g
<3.4
D
Minimum descent time on test track
s
<11.5
E
Damping coefficient adjustment range
Ns/m
>100
F
Maximum travel (26 in. wheel)
mm
43
G
Rake offset
mm
38
H
Lateral stiffness at the tip
kN/m
>75
I
Total mass
kg
<1.4
J
Lateral stiffness at brake pivots
kN/m
>425
K
Headset sizes
in
1.000
1.125
L
Steertube length
mm
150
170
190
210
230
M
Wheel sizes
list
26 in
Stage 8: Refined set of specifications
Metric
No.
Metric
Units
Value
N
Maximum tyre width
in
>1,75
O
Time to assemble to frame
s
<45
P
Mudguard compatibility
list
Zefal
Q
Instils pride
subj.
>4
R
Unit manufacturing cost
US$
<80
S
Time in spray chamber without water entry
s
>3600
T
Cycles in mud chamber without contamination
k-cycles
>25
U
Time to disassemble/assemble for maintenance
s
<200
V
Special tools required for maintenance
list
hex
W
UV test duration to degrade rubber parts
hours
>450
X
Monster test cycles to failure
cycles
>500k
Y
Japan Industrial Standards test
pass/fail
pass
Z
Bending strength (frontal loading)
kN
>10.0
Stage 8: Refined set of specifications (cont’d)
The Design Core
CONCEPT DESIGN
Concept Generation
Clarify problem
analyse into sub-problems
determine basic requirements
External search
interview users, consult experts,
patent search
Internal search
brainstorming, analogy, inversion,
staff consultation
Combination
Concept Analysis
Controlled convergence
Rating & weighting method
Market
Assessment
Specification
Concept
Design
Detail
Design
Manufacture
Sell
Concept Design: Car Horn
Concept Design: Evaluation
Criterion
Concept
1
2
3
Ease of achieving 105-125 DbA
S
-
Ease of achieving 2000-5000 Hz
S
S
Resistance to corrosion, erosion and water
-
Resistance to vibration, shock and acceleration
4
5
6
7
8
9
10
11
12
13
14
+
-
+
+
-
-
-
-
S
+
N
+
S
S
+
S
-
-
-
S
+
-
O
S
-
-
S
-
+
-
-
-
S
S
-
T
S
-
S
-
-
S
-
-
-
-
S
-
-
-
S
S
-
-
S
S
Resistance to temperature
D
S
-
Response time
A
S
-
E
+
-
-
-
-
S
-
-
-
-
Complexity: number of stages
T
-
+
V
S
+
+
-
-
-
+
+
-
-
Power consumption
U
-
-
A
+
-
-
+
-
-
-
-
S
+
Ease of maintenance
M
S
+
L
+
+
+
-
-
S
+
+
S
-
Weight
-
-
U
+
-
-
-
S
-
-
-
-
+
Size
-
-
A
S
-
-
-
-
-
-
-
-
-
Number of parts
S
S
T
+
S
S
-
-
+
-
-
S
-
Life in service
S
-
E
+
-
S
-
-
-
-
-
-
-
Manufacturing cost
-
S
D
-
+
+
-
-
S
-
-
-
-
Ease of installation
S
S
S
S
+
-
S
-
-
-
S
-
Shelf life
S
S
S
S
-
-
S
S
S
S
S
S
0
6
10
2
9
5
8
1
7
3
9
4
5
7
4
3
12
1
0
11
5
2
8
6
2
13
1
2
13
1
0
8
8
4
9
3
Σ+
ΣΣS
Concept Design: Evaluation/Generation
Initial number of
concepts based
on PDS
Initial number
reduced
Apply controlled
convergence (CC)
Apply concept
generation (CC)
New ones added
CC
Further
reduction (FR)
CG
Further addition
(FA)
CC
FR
CG
FA
CC
CONCEPT SELECTED
Concept Design: Rating & Weighting
Rating
Rating x Weight Factor
Weight
Factor
C’pt
1
C’pt
2
C’pt
3
C’pt
4
C’pt
1
C’pt
2
C’pt
3
C’pt
4
Make 20,000 brushes
per 8-hour shift
4
5
5
0
5
20
20
0
20
End of brush safety
5
0
5
5
5
0
25
25
25
Ease of manufacture
of machine
3
4
0
3
4
12
0
9
12
Reliability of
operations
5
4
2
4
4
20
10
20
20
Overall size of
machine
2
3
4
3
3
6
8
6
6
Cost
3
3
2
3
3
9
6
9
9
Good filament density
4
3
5
5
5
12
20
20
20
79
89
89
112
Objective
Total
Example: Design of a machine to make bottle brushes
The Design Core
Market
Assessment
Specification
DETAIL
DESIGN
Concept
Design
Detail
Design
Manufacture
Sell