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7/30/2019 Future of Automotive Body Materials
1/28
Massachusetts Institute of TechnologyCambridge, Massachusetts
Future of Automotive Body Materials:Steel, Aluminum & Polymer Composites
Hoogovens Technology DayOctober 1998
Professor Joel P. ClarkMassachusetts Institute of Technology
Massachusetts Institute of TechnologyCambridge, Massachusetts
Introduction
Vehicle Lightweighting Key To Next Generation Product Development
Improved Efficiency, Reduced Emissions
Performance Improvement
Increased Weight & Power Consumption of Vehicle Accessories
Active Discussion Of Wide Range Of Approaches
Advanced Materials
New Powerplants
Novel Control Systems
Potential For Radical Change In Vehicles, Vehicle Development and Vehicle Design
Massachusetts Institute of TechnologyCambridge, Massachusetts
Is It Time For A Leap To A New Vehicle Technology?
New Technologies Under Development/Consideration
Ultra-Lightweight Vehicles
Advanced Powertrains (hybrids, Electric, fuel cells)
Computers On Wheels
Who's Going To Build These Vehicles?
Current Producers or
New Entrants
Recall The California EV Strategy As Specifically Directed Toward Developing A NewVehicle Production Industry
Will That Happen This Time?
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
"Hypercars" Are Not The Answer
Manufacturability The Key Limitation
Scale Economics Limit Polymer Strategies
Technologies To Increase Processing Rates Problematic
Metals Technologies Better-Suited To Current Scale Requirements
Aluminum Initiatives
Steel ULSAB
Note: Materials Processing, Not Merely Material, Is The KeyEnabling Factor
Massachusetts Institute of TechnologyCambridge, Massachusetts
Probably Not
High Risk
Economically Tenuous
Strategically Weak
Some Radical Innovations Should Be Pursued
But They Should Not Be The Centerpiece Of Product Strategy
Examples From Materials Field
Steel Versus ...
Is Radical Innovation The Answer?
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Automobile Recycling Technology &Strategic Implications For Recycling Policy
Issue
Rising Tide of Public and Private Concerns About Obsolete Vehicles
Variety of Actions Proposed, With Varying Consequences For The Industry
Findings
Notwithstanding the Concerns, Vehicle Recycling Is Not A Major EnvironmentalProblem
Rather, The Issues, Both Historically and Currently, Stem From Economic Driversand the Nature Of Market For Secondary Products & Materials
Further, Policy Directions Fail To Recognize Key Distinctions Between ProductCharacteristics (Recyclability) and Market Features (Recycling)
Value to Industry
Development Of Context For Discussion
Demonstration Of Impact Of Underlying Structure Of The Problem
Recommendations For Action By Industry And By Governments
Massachusetts Institute of TechnologyCambridge, Massachusetts
Application and Value Of Life Cycle Analysis InVehicle Design & Development
Issue
Life Cycle Analysis An Emerging Analytical Framework
Application To Designs Internally
Potential For Larger Context (Regulatory Application)
Findings
LCA Is Not A Value-Free Method; Context Is Vital Element Of Its Use
Nevertheless, Potential For Better Insight Into Product & Process Decisions
Much Work To Be Done
Value to Industry
Development Of Argument To Frame Question Of LCA Utility
Demonstration Of Both The Impact Of Context As Well As Potential Use
Ongoing Dialog and Development Of Better Methods For Incorporation OfEnvironmental Considerations In Product Strategy
Massachusetts Institute of TechnologyCambridge, Massachusetts
Preferred Approach
Inventoryspecies s
medium m
location x
time t
Impact AnalysisDose-response givesextent of effects
to Receptor Cells
EnvironmentalEffectsAQM gives
Conc (t,x)
Valuationbased on WTP
Damage
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Base Case: Convergence for Steel
CO2
NOx
SO2
CO
C6H6
C20H12
H2S
Cd
N2)
F-
AsH3
Cr
Zn
Se
SO4
$0.0 $0.5 $1.0 $1.5 $2.0 $2.5 $3.0 $3.5
$Externalities to Air
Extraction
ProcessingUse
Massachusetts Institute of TechnologyCambridge, Massachusetts
Base Case: Convergence for Aluminum
CO2
PAH
SO2
HF
Cu
HCl
Pb
Cd
As
N2O
Ni
B
NH3
Co
V
$0.0 $0.5 $1.0 $1.5 $2.0 $2.5 $3.0 $3.5
$Externalities to Air
Extraction
Processing
Use
Massachusetts Institute of TechnologyCambridge, Massachusetts
BIW Demonstration Analysis
Problem: Select BIW design
Key Assumptions:
Sheet is made from 100% primary material
End-of-Life scrap is recycled once with 85% efficiency
Fuel Economy: 22 MPG for Steel
Steel ULSAB Aluminum Unibody
Steel Sheet 200 kg 18 kg
High StrengthSteel Sheet 50 kg 185 kg
Al Sheet 141 kg
TOTAL BIW 250 kg 203 kg 141 kg
TOTAL Car 1400 kg 1353 kg 1291 kg
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Basis for Comparison
LCI Data by IKP Stuttgart
Materials, Manufacturing, Use, Recycling
Several Modifications
Application of XLCA
Base Case $/kg
Sensitivity Analysis
Massachusetts Institute of TechnologyCambridge, Massachusetts
Environmental Damage Cost Comparisons
Steel
ULSAB
Aluminum0
100
200
300
400
DamageCostsPerBIW
Toxics
Criteria
GHGsSteel
ULSABAluminum
0
100
200
300
400
DamageCostsPerBIW
Use
Materials
Massachusetts Institute of TechnologyCambridge, Massachusetts
Sources of Environmental Damage for Each Material
Steel$347
$121
$67
$40
$33
$17
$12
$5
$4
$1
$3
$0 $40 $80 $120
Damage
Aluminum$308
$128
$50
$41
$37
$17
$14
$5
$4
$5
$2
$0 $50 $100 $150
Damage
ULSAB$310
ProductionUse
$143
$57
$46
$41
$20
$15
$6
$5
$7
$2
CO2
SO2
NOx
VOC
PM10
PAH
N2O
CH4
Pb
Cr
$0 $50 $100 $150 $200
Damage
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity Analysis
How Wrong Do You Have to Be for Ranking to Change?
Bottom-Up Investigation
Variations in Assumptions...
Changes $/kg Estimates...
Which May or May Not Change the Ranking
Top-Down Investigation
Validate Results Against National Figures
Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity of $/kg of SO2 to Changes in Assumptions
0 1E-05 2E-05 3E-05 4E-05 5E-05 6E-05 7E-05 8E-05
Deaths/person-day-ug/m3
0
10
20
30
40
50
$/kgSO2
Base CaseValue
2.4E-5
High Value
in Literature
7.2E-5
Low Value
in Literature
8E-7
Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity of Steel-Aluminum Ranking to $/kg Valuations
0 100
$/kg SO2
0
100
200
300
400
500
600
700
800
Total $/BIW
Steel
Aluminum
BaseCase
$13/kg
Low Mortality
$2.40/kg
High Mortality
$36/kg
Crossover
$65/kg
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Distance to Crossover for Steel and Al
AIR RELEASESSO2
PM10CF4
CrC2F6B(a)P
NiHF
BAs
HClV
CoCu
ZincWATER RELEASES
PbHgAs
HClPhenolNH4+
ZincCN-
0 2 4 6 8 10Log10 [Crossover$/kg /Base$/kg]
Massachusetts Institute of TechnologyCambridge, Massachusetts
(In)Sensitivity of Aluminum-Steel Ranking
Species(to Air)
Base$/kg
$/kg required forSteel to beat Al
National AnnualDamage Implied byCrossover Value
SO2 13 65 $1.2 trillionPM10 13 138 $6.2 trillionArsenic 2,800 3 million $37 trillion
B(a)P 243 130,000 $88 trillion
U.S. GDP is $7 trillion.
Estimates higher than this are absurd.
===> Aluminum is preferable to steel, given assumptions
Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity of Aluminum-ULSAB Ranking
Many of these crossovers values are possible, given theuncertainties and subjective judgments in the model
===> ULSAB and Aluminum are too close to call
Species(to Air)
Base$/kg
$/kg required forSteel to beat Al
National Annual DamageImplied by CrossoverValue
Pb 1400 1900 $8.5 billion
SO2 13 15 $280 billion
GHGs 0.014 0.007 $43 billion
VOCs 1.34 0.42 $8.8 billion
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity of ULSAB-Aluminum Rankingto Changes in Inventory Allocation Assumptions
0 1 2 3 4 5
Number of Times Aluminum is Recycled
260
280
300
320
340
$/BIW
Assuming Steel is Recycled Once With k=2All recovery efficiencies are 85%
Aluminum @ k=1
$310
Aluminum @ k=2
$279
$262
ULSAB
Massachusetts Institute of TechnologyCambridge, Massachusetts
Conclusions
Cases Demonstrate Ability to Rank Alternatives(or Determine that Several are Indistinguishable)
Few Pollutants Matter
Can Focus on a Few Drivers
Can Test Robustness of Ranking
Bottom-Up Approach, Revisiting Analysis
Top-Down Scale Analysis
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Automobile Product Innovation
Variety of Drivers
Customers
Governments
OEMs
Performance Targets Increasingly Stringent
Environmental - Air Emissions, Recyclability
Efficiency - Fuel EconomySafety
Comfort
Affordability/Manufacturability
Leading to Increased Product Complexity/Content
Safety Systems
Entertainment Systems
Navigation Aids
Massachusetts Institute of TechnologyCambridge, Massachusetts
Where Is This Innovation Coming From?
Traditional View:
Carmakers Develop Product Responses To Meet Product Goals, Customer Demands,Government Constraints/Controls
Current Situation, However, Differs From This View
Carmaker Role Is Changing
Costs Of R&D Increasingly Being "Farmed Out"
Technology Innovation Increasingly In The Hands Of Suppliers
Issues
How To Foster Development Of New Technology- What Is The Appropriate Technology Development Model?
Ownership Of Technology- Whose Technology Is It?
Implications For Industry Development
Examples In Materials Technology & Technology Push For LightWeight Cars
Massachusetts Institute of TechnologyCambridge, Massachusetts
Materials Technology & Automobiles
Henry Ford's Innovations Leading To Modern Automobile Industry
Manufacturing Organizat ion - Assembly Line
Labor Relations/Economics - "$5/day wage"
Manufacturing Technology - Steel Automobiles
Consequences For Ford
Need To Become Steel Specialists
At The Peak Of Their Integration, Active In All These Aspects
Effluent/Waste
Resources/RawMaterials
Vehicle
Disposal
VehicleDistribution,Sale&Use
VehicleAssembly
Subassembly/ComponentManufacture
PartsFabrication
MaterialsRefining
&Processing
PrimaryMaterialsExtraction
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Steel - Then
Advantages
Amenable To High-Speed Fabrication Technologies
Inexpensive Material
Good Engineering Properties; Tailorable
Valuable Offal - "Waste" Has Market Value
Many Suppliers, Largely Indigenous
Disadvantages
Relatively High Density
Corrosion - Necessitates Expensive Processing
Massachusetts Institute of TechnologyCambridge, Massachusetts
Changes Thru 1970's
Steel Industry
Ford's Vertical Integration Ultimately Viewed As Inefficient
Integrated Steel Producers Focus Upon Specialized Materials and Processing
Steel Industry Complacent About Automobile Customers
Development Of Overseas Steel Production Capacity;Notably Japanese Producers/Innovators
Automobile Industry
By Mid-to-Late 1960's, Automobile Companies Develop Unibody Design Rules;Sheet Metal/Spot Welding Emphasis; Shell Structures; Lighter Weight
By Mid-to-Late 1970's, Automobile Companies Reevaluating Need For In-HouseMaterials Specialists
In Some Cases, Wholesale Decimation Of In-House Material Capabilities
Massachusetts Institute of TechnologyCambridge, Massachusetts
1980's
Emergence Of
New Design Imperatives;CAFE & CAA Start To Bite
Increased Competition, In Both Automobile and Materials Industry
Changing Roles For Both
Weight Reduction Imperatives Lead To Two Major Design Trends
Reduction In Vehicle Size -- "Downsizing"
Changes In Vehicle Material Composition
New Major Vehicle Design Concept Emerges
Space Frame Design
Skins Not A Part Of Vehicle Structure; Relaxes Performance Requirements
Pontiac Fiero -- A Success and a Failure
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Fiero - A Demonstration Of Key Industry Weakness
Capitalized Upon By Polymer Industry In US, Steel Industry In Japan
Development of Customized Materials And Processing Technologies
Targeted At Automobile Applications
Leading To Development Of Automobile Design Experience Outside Of Automobile
OEMs and Design Houses
Challenge To Entrenched Steel Suppliers And Steel Designers
Slow To Respond
Weak Responses When Made
However, Able To Continue To Exploit Downsizing StrategyThrough Much Of The 1980's
Coupled With New Powerplant/Powertrain Development
Massachusetts Institute of TechnologyCambridge, Massachusetts
1990's -- Emergence Of New Pressures
Lightweighting Through Materials Choice Brought Up Short By Recycling Issues
Clean Air Act & Amendments, Rather Than CAFE, Industry Design Driver
Fuel Economy As Air Pollution Reduction
Alternative Fuels/Fuel Sources
Need To Become Proactive About Vehicle Performance
Safety
Economy
Environment
Aggressive Polymer Development Blocked
Recycling Issues
Failure To Accomplish Promised Performance
Massachusetts Institute of TechnologyCambridge, Massachusetts
Light Metals As Remaining Alternative
Aluminum
Advantages DisadvantagesDi ff eren t Form ing Techni ques Di ff erent Form ing Techn iques
Less Dense Less StiffCompatible With Current Steel Practice Just Different Enough To Be DifficultMore Recyclable, In Principle, Than RP/C Nastier Primary Extraction ProcessesGlut On The Market Relatively ExpensiveCorrosion Resistant Incompatible With Steel Fastening
Aluminum Suppliers Anxious To Develop New Markets
Substantial Investment In Design, Process Technology Development
Willing To Offer Price Stability
Competing Concepts, Development
7/30/2019 Future of Automotive Body Materials
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Aluminum Economics
More Expensive Than Steel
Ingot -> Conversion -> Sheet
Hard To Reduce Ingot Costs; Opportunities To Reduce Conversion Costs
Differences In Forming and Assembly
Won't Reduce Costs
May Increase Cost
Two Basic Approaches To Consider Cost
More Lightweight Vehicle; Worth Additional Expense, or
Redesign Product and Process To Control Costs
Both Approaches Taken; Latter Relies Upon Major Supplier Innovation and Support
Massachusetts Institute of TechnologyCambridge, Massachusetts
Automaker And Aluminum Development/Control Points
Stamping Development and Research At All OEMs
Large Aluminum Panels As Classic EPA Weight Class Stopgap
Effort To Move Beyond To Understand Forming Processes
Aluminum Suppliers Believe OEM Know-How Still Inadequate
Extrusion Development
Technology Largely Retained By Aluminum Companies
Especially Development Of Complex Extruded Geometries
Casting Development
Know-how Widely Dispersed Already
Aluminum Companies Emphasize Metallurgical Know-how & Alloy Development
Design Work
OEMs Working To Develop Analytical, Rather Than Normative, Designs
Aluminum Companies Exploiting Superior Materials Know-how In Design, FormingTechnology Development, And Assembly Technology Development
Massachusetts Institute of TechnologyCambridge, Massachusetts
Materials Technology: In Whose Hands?
Certainly Materials, Design & Forming Technology Originally Under OEM Control
Suppliers As Producers Of What OEMs Ask For, Rather Than Active Partner
Steel Emerged As Material Of Choice, With Associated EntrenchmentIn OEM Organizations
Relative Inertia In Vehicle Structural Development Limited Value Of In-House MaterialsKnow-How
Normative Design Processes; Rules of Thumb; Cost vs. Performance Driven
Reinforced Steel's Position; Led To Poor Understanding Of Steel Supplier Failings
With Re-emergence Of Performance Requirements, Exposure Of Limitations
However, Suppliers Demonstrated An Ability To Provide Design and ProcessDevelopment As Part Of Material Sales Pitch
Suppliers Emerge As Partner In Product Development
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Does Control Of Materials Technology Mean Control Of ProductDevelopment?
On The Face Of It, No -- Not Yet, Anyway
Barriers To Exploitation Of That Competency Limit Position Of Suppliers
Requires A New Producer, Exploiting New Material Technology Effectively To ChangeThat Relationship
Aluminum
Current Efforts In Aluminum Bodies Are Largely Evaluative, Rather Than
CommitmentsOEMs Are Demanding Major Price Concessions In Order To Consider Aluminum;May Require Similar Technology Concessions, Especially In Forming
Steel
Remains Major Automotive Material, With Entrenched Investment
Is No Longer The "Default" Automobile Material
OEMs Investing To Become More Material Flexible
Polymers
May Yet Reemerge; Substantial Technological Development In Place
Issue Of Effective Use Thereof
Massachusetts Institute of TechnologyCambridge, Massachusetts
Materials Technology As Exemplar Of Emerging TechnologyDevelopment Trend In Automaking
A Possible Evolution
Initial Development Wholly Within OEM Domain
As Suppliers Learn The OEM Business, Push To Develop Technology To MeetCustomer Needs
As Vehicle Challenges Become More Numerous and Difficult, OEM Relies UponSupplier For More and More Technology Development
OEM Ultimately Turns The Bulk Of Technology Development Over To Supplier
Effect: Transfer Of Technology/Development Risk From OEM To Supplier?
Massachusetts Institute of TechnologyCambridge, Massachusetts
Diversification Of R&D Risk:Wide Range Of R&D Experiments
OEM Efforts
Precompetitive Research Partnerships - USCAR
Joint OEM-Government
Program for a New Generation of Vehicles
OEM-Supplier Efforts
Subgroups Within USCAR
Industry Associations/OEMs - e.g., ULSAB or Steel/Auto Partnership
Product Efforts- Audi A-8/Alcoa; Ford Concept 2000/Alcan; Saturn EV-1/Alcoa&Alcan
OEM/Suppliers/Government/Academics
IMVP, University of Michigan, etc.
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Massachusetts Institute of TechnologyCambridge, Massachusetts
TWB Cost Modeling Assumptions
Laser Welding Line Cost $3.3 milliontwo-axis CO2 laser weld station, 6 kWbeam weaving capabilityload/unload automation
Set-up Time 7 second/weld
Down Time in Welding 10 %
Reject Rate in Welding 3 %
Reject Rate in Stamping 1 %
No. of Laborers 3/welding line
High Strength Steel Price 0.39 $/lb
Scrap Price 0.05 $/lb
Welding Speed 128 inches/minute
No precision shear or dimpling
Aluminum Price 1.50 $/lb
Scrap Price 0.30 $/lb
Welding Speed 72 inches/minutePrecision Shear Equipment $300,000
Massachusetts Institute of TechnologyCambridge, Massachusetts
Tailor Welded Blank Considerations
Steel Aluminum
Blank Holding Magnetic Complex Fixturing
Formability Possible difficulty atweld site
Possible difficulty atweld site
Precision Shear Part dependent Almost always required
Laser System/ MashSeam Welding
CO2 or Nd:YAG, MSWpossible
CO2 or Nd:YAGMSW difficult
Beam Issues High quality desired High quality required,Higher power densitiesneeded, Tightly focusedbeam
Coatings Problems with zinccoatings
Problems with oxidelayer
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Case 1 - Two Piece Outer Steel Body Side Design
Two piece outer design
Quarter panel outer
Door frame opening
Necessary reinforcements
Massachusetts Institute of TechnologyCambridge, Massachusetts
Case 2 - One Piece Outer Steel Body Side Design
One piece body side, ordinary blank
Uniform thickness body side outer
Necessary reinforcements
Massachusetts Institute of TechnologyCambridge, Massachusetts
Case 3 - One Piece Steel Body Side Design
0.7 mm
1.3 mm
1.2 mm
1.4 mm1.8 mm
1.5 mm
1.2 mm
0.8 mm
Number of Blanks: 8
Number of Welds: 9
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Case 4 - One Piece Aluminum Body Side Design
Number of Blanks: 4
Number of Welds: 5
1.2 mm
2.4 mm
3.0 mm
2.0 mm
Massachusetts Institute of TechnologyCambridge, Massachusetts
Cost Breakdown for Various Body Side Outer Designs ($/part)
Case 1:Steel Unibody
Case 2:Steel Unibody
Case 3:1 piece Steel
Case 4:1 piece
Aluminum
Materials $23.58 (21%) $23.49 (27%) $19.76 (38%) $45.63 (57%)
Blanking $1.48 (1%) $1.15 (1%) $2.08 (4%) $1.11 (1%)
Welding (0%) (0%) $15.98 (30%) $11.64 (15%)
Stamping $74.80 (66%) $51.76 (58%) $14.64 (28%) $21.26 (27%)
Assembly $13.76 (12%) $12.63 (14%) (0%) (0%)
Total $113.62 $89.03 $52.46 $79.64
Massachusetts Institute of TechnologyCambridge, Massachusetts
Cost Breakdown for Tailor Welded Body Side Outers
Material
57.3%
Labor4.2%
Energy0.9%
Main Machine9.0%
Tooling19.1%
Fixed Overhead4.8%
Building0.6%
Aux. Equipment1.8%
Maintenance2.3%
Aluminum - $79.64Material34.3%Labor
9.6%
Energy2.2%
Main Machine16.0%
Tooling20.6%
Fixed Overhead8.6%
Building1.3%
Aux. Equip3.2%
Maintenanc4.1%
Steel - $52.46
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity to Welding Speed for Aluminum TW Body Sides
Aluminum
Baseline
Steel 1 PieceBaseline
50 70 90 110 130 150
Welding Speed (in/min)
50
60
70
80
90
Cost
($)
Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity to Weld Length in Al Design for Body Side Outers
Aluminum
1 Piece
Baseline
Steel 1 PieceBaseline
50 70 90 110 130 150
Weld Length (in)
$50
$60
$70
$80
$90
$100
Cost($)
Massachusetts Institute of TechnologyCambridge, Massachusetts
Sensitivity to Aluminum Price for Body Side Outers
Aluminum
Baseline
Steel 1 PieceBaseline
$1.00 $1.10 $1.20 $1.30 $1.40 $1.50 $1.60 $1.70 $1.80
Aluminum Price ($)
$50
$60
$70
$80
$90
$100
Cost($/lb)
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Aluminum Spaceframe Design Layout
Massachusetts Institute of TechnologyCambridge, Massachusetts
Vehicle Design Philosophy and Specifications
Unibody vs. Spaceframe Design
Single Material Type vs. Metal Mix
Multiple Joining Techniques
SteelUnibody
AluminumUnibody
AluminumSpaceframe
SF-1
AluminumSpaceframe
SF-2
AluminumSpaceframe
SF-3
Stamping 615 310 105 95 112
Extrusion 200 149 145
DieCasting
40 75
--------------- --------------- --------------- ---------------- ----------------- -----------------
Total 615 310 305 284 332
Massachusetts Institute of TechnologyCambridge, Massachusetts
Cost Results: Aluminum Part Forming Processes
Extrusion
Die Casting
Stamping
$0
$5
$10
$15
$20
$25
Cost/lb($)
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Assumptions Concerning Cost Assessment
Part Production
Spaceframe: Multiple Designs
Unibody Designs: Single Design For Entire Production Volume Range
Assembly
Unibodies: Spot Welding, Adhesive Bonding
Spaceframes: Arc/Spot Welding, Adhesive Bonding, Mech. Fastening
Assumption of Two BIW Assembly Setups:
Massachusetts Institute of TechnologyCambridge, Massachusetts
Production Cost Results
Annual ProductionVolume20,000
Annual ProductionVolume100,000
Annual ProductionVolume300,000
SpaceframeSF-1
$4,472 N/A N/A
SpaceframeSF-2
N/A $2,925 N/A
SpaceframeSF-3
$6,073 $2,791 $2,404
Aluminum Unibody $7,249 $3,602 $2,058
Steel Unibody $5,774 $2,545 $1,417
Massachusetts Institute of TechnologyCambridge, Massachusetts
BIW Production Cost Breakdown
St. Unib.Al. Unib.
SF-1SF-3 St. Unib.
Al. Unib.SF-2
SF-3 St. Unib.Al. Unib.
SF-3
$0
$1,000
$2,000
$3,000
$4,000
$5,000
$6,000
$7,000
$8,000
$9,000
BIW Production Cost
Assembly
Part Production
20,000 BIW/Year
300,000 BIW/Year
100,000 BIW/Year
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Conclusions
Cost
Spaceframe Cost Effective at Low Production Volumes
Aluminum Designs Compete with Steel Unibody:
Airborne Emissions
Aluminum Designs Always Better for Pollutants Associated with Use
Aluminum Burdened by Process Related Emissions in Mining/Refining
Even if Tradeoffs between Cost-Emissions Are Not Considered, Aluminum VehiclesMay Be Commercially Successful.
Massachusetts Institute of TechnologyCambridge, Massachusetts
Latest Steel-Aluminum Body Competition
Past MSL Work Focused On Space Frame Concepts
Some Evaluation of Advanced Sheet Metal Processes
New Thinking In Body Concepts Emerging
More Refined Aluminum Designs
Mixed Metal Concepts - Aluminum & Steel
Exotic Material Processing Options & Body Designs
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Composite / Steel Cost Comparison: Utility
Composites offer the following:
Advantages
Parts Consolidation Opportunities
Primary / Secondary Weight Savings
Low Investment Costs
Increased Design Flexibility
Disadvantages
Materials and Labor Intensive Process
Long Cycle Times
Non-traditional Manufacturing Technology
What is the competitive position of composite parts compared to its steelcomparator?
Massachusetts Institute of TechnologyCambridge, Massachusetts
Cost Analysis: Methodology
Composites Vehicle Design
Ford Composite Intensive Vehicle (CIV)
Complete Body in White : 8 pieces
BIW Weight : approx. 300 kg
Steel Comparator
Honda Odyssey minivan
Based on Accord chassis, so comparable size
BIW Weight : approx. 400 kg
Use steel stamping and assembly models to estimate Odyssey's BIW cost
Use RTM and composites assembly models to estimate CIV's BIW cost
Identify key process variables, cost drivers, necessary technical improvements
Massachusetts Institute of TechnologyCambridge, Massachusetts
Trim
CureReactionInjectionMold
Trim
Thermoform
CutReinforcementMaterial
Foam Core /PreformSubassembly
ResinTransferMolding
Trim/Inspect
Preforming
Foam Core Molding
Resin TransferMolding
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Massachusetts Institute of TechnologyCambridge, Massachusetts
General RTM Cost Model Structure
Inputs:
Material Composition
Part Geometry
Preform, FoamCore Geometry
Exogenous Cost Factors
Process Conditions
Parameter
Estimation Data
Secondary
Calculations:
Cycle Time
Estimation
Machine CostEstimation
Number of
Machines
Tooling Cost
Estimation
Number of Tools
Cost Estimation
per Operation
and
Cost Summary
Massachusetts Institute of TechnologyCambridge, Massachusetts
Resin Transfer Molding Cycle Time Estimation
Cycle Time = Preparation Time + Fill Time + Cure Time
Preparation Time:
Fill Time:
Cure Time:
Massachusetts Institute of TechnologyCambridge, Massachusetts
RTM Fill and Cure Equations
Fill Time
Based on application of D'Arcy's Law: Q = -(KA/m) dp/dx, where Q = volumetric flowrate, K=permeability, A=cross-sectional area, m=viscosity and dp/dx = pressuregradient
Assumptions:
Cure Time
dc/dt = (k1 + k2 c^m) (1-c) n, where c=degree of conversion, k1 and k2 areArrhenius constants, and m,n are empirical constants
Assume m = 0, n = 2,
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Massachusetts Institute of TechnologyCambridge, Massachusetts
RTM Fill Time Process Flow
Rectilinear or
Radial Flow?
Line Source
or Sink?
Line Sink
Calculation
Rectilinear
Calculation
Radial
Calculation
Rectilinear or
Radial Flow?
Rectilinear
Calculation
Line Source
Calculation
Constant Flow
or Pressure?
Massachusetts Institute of TechnologyCambridge, Massachusetts
RTM Machine and Tooling Cost Equations
Machine Cost = C1 + C2 x (Clamping Force Requirement) + C3 x (Platen Area)
C1, C2, C3 : regression constants
Clamping Force = f(maximum injection pressure, mold geometry and mold design)
Tooling Cost = C1 + C2 x (Part Weight) C3 + C4 x (Part Surface Area)
C1, C2, C3, C4 : regression constants, dependent on tool material
Tool Material Options
Massachusetts Institute of TechnologyCambridge, Massachusetts
Effect of Mold Design on Fill Time and Machine Cost
Fill Time (sec) Mold Force (N) Press Cost ($)
Rectilinear,Constant Flow
12.15 5.4 x 106 $3,012,346
Rectilinear,Constant Pressure
249.11 4.03 x 105 $355,782
Radial Source,Constant Pressure
233.45 9.04 x 104 $176,850
Radial Sink,Constant Pressure
15.54 1.36 x 106 $903,743
Flow Length = 1.4m (Rectilinear), 0.7m (Radial)
Initial Injection Pressure = 5 x 105 N
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Materials Prices:
Resin (Vinyl Ester) $2.60 / kg
Filler (Calcium Carbonate) $0.13 / kg
Reinforcement:
$2.00 / kg
$11.00 / kg
$6.50 / kg
Catalyst $3.24 / kg
Foam Core (Polyurethane) $2.54 / kg
Foam Core Molding, Thermoforming and RTM Tool Material: Steel
RTM Flow: Rectilinear, Constant Pressure
32 Steel Inserts
RTM Cost Modeling Assumptions
Massachusetts Institute of TechnologyCambridge, Massachusetts
Key Carbon Fiber Design Assumptions for CIV
Use simple beam loading equations to estimate the equivalent thickness of carbonfiber part compared its glass fiber equivalent
Ratio of moduli determines the thickness of the carbon fiber part
Elastic Modulus (Msi):
Part thickness for glass fiber component : 3 mm
Results
Part thickness:
Relative Weight assuming calculated thicknesses (Glass fiber = 1.0)
Massachusetts Institute of TechnologyCambridge, Massachusetts
Key SMC Design Assumptions for CIV
SMC part thickness : 4 mm
Reinforcing rib structure placed every 150 mm
Reinforcing rib dimensions
Length = 150 mm
Height and Width are dependent on part geometryFoam cores assumed in parts where crush resistance is necessary
Front End rails
Floorpan
SMC part is composed of two halves forming a closed section
Rib
Rib Pattern
PartCross-Section
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Comparison of Part Weights (including CIV inserts)
172
193.6
241.3
286.2
367.9
Carbon Fiber
Carbon/Glass
Glass Fiber
SMC
Steel
0 100 200 300 400
Weight (Kg)
Bodyside Floorpan Cross Member Front End Roof
Massachusetts Institute of TechnologyCambridge, Massachusetts
10 20 30 40 50 6030 35
Annual Production Volume (x 1000)
$1,000
$1,500
$2,000
$2,500
$3,000
Steel
RTM Glass
RTM Carb
RTM Ca/Gl
SMC
(Composites Wage: $25/hr)
SMC-Steel
Break-even Point:
~30,000 vehicles/yr RTM Glass-Steel Break-evenPoint: ~35,000 vehicles/yr
Massachusetts Institute of TechnologyCambridge, Massachusetts
Manufacturing Cost Breakdown: Glass vs Carbon Fiber
Glass Carbon Car/Gla
$0
$500
$1,000
$1,500
$2,000Other Fixed
Tooling
Equipment
Energy
Labor
Materials
(Volume = 35,000)
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Cost per Kilogram Saved (Relative to Steel Base Case)
5 20 35 50 65 80 95 110 125 140
Annual Production Volume (x 1000)
($5)
($4)
($3)
($2)
($1)
$0
$1
$2
$3
$4
$5
CostperK
gSaved
RTM Glass
RTM Carb
RTM Ca/Gl
SMC
Massachusetts Institute of TechnologyCambridge, Massachusetts
5 20 35 50 65 80 95 110 125 140
Annual Production Volume (x 1000)
$50
$100
$150
$200
Steel
RTM
SMC 5%
SMC 30%
Steel: 9 parts
RTM: 2 Parts
SMC: 1 Part
Massachusetts Institute of TechnologyCambridge, Massachusetts
5 20 35 50 65 80 95 110 125 140
Annual Production Volume (x 1000)
$400
$500
$600
$700
$800
Steel
RTM
SMC 5%
SMC 30%
teel: 57 parts
RTM: 2 parts + 20 inserts
SMC: 9 parts + 20 inserts
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Hybrid Vehicle Scenarios
515
2535
4555
6575
8595
105115
125135
145
Annual Production Volume (x 1000)
$1,000
$1,200
$1,400
$1,600
$1,800
$2,000
Steel
Hybrid 5%
Hybrid 30%
RTM
SMC
Hybrid Vehicle
Bodyside: SMC (5-30% Scrap)
Floorpan/Cross Member: RTM
Front End: RTM
Roof: Steel
Massachusetts Institute of TechnologyCambridge, Massachusetts
Hybrid Vehicle Scenarios
0 50 100 15056 92
Annual Production Volume (x 1000)
$1,000
$1,200
$1,400
$1,600
$1,800
$2,000
Steel
Hybrid 5%
Hybrid 30%
RTM
SMC
Hybrid Vehicle
Bodyside: SMC (5-30% Scrap)
Floorpan/Cross Member: RTM
Front End: RTM
Roof: Steel
Massachusetts Institute of TechnologyCambridge, Massachusetts
Hybrid Vehicles: Cost per Kilogram Saved
5 20 35 50 65 80 95 110 125 140
Annual Production Volume (x 1000)
($5)
($4)
($3)
($2)
($1)
$0
$1
$2
$3
$4
$5
CostperKgSaved
Hybrid 5%
Hybrid 30%
RTM
SMC
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Massachusetts Institute of TechnologyCambridge, Massachusetts
Total cost of composites BIW is competitive with steel at low production volumes (
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