future of automotive body materials

7/30/2019 Future of Automotive Body Materials

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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


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


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?


2/28


"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


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?


3/28


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


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


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


4/28


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


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


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


5/28


Basis for Comparison

LCI Data by IKP Stuttgart

Materials, Manufacturing, Use, Recycling

Several Modifications

Application of XLCA

Base Case $/kg

Sensitivity Analysis


Environmental Damage Cost Comparisons

Steel

ULSAB

Aluminum0

100

200

300

400

DamageCostsPerBIW

Toxics

Criteria

GHGsSteel

ULSABAluminum

0

100

200

300

400

DamageCostsPerBIW

Use

Materials


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


6/28


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


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


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


7/28


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]


(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


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


8/28


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


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


9/28


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


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


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


10/28


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


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


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


11/28


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


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


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


12/28


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


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


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


13/28


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


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?


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.


14/28


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


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


15/28


Case 1 - Two Piece Outer Steel Body Side Design

Two piece outer design

Quarter panel outer

Door frame opening

Necessary reinforcements


Case 2 - One Piece Outer Steel Body Side Design

One piece body side, ordinary blank

Uniform thickness body side outer

Necessary reinforcements


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


16/28


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


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


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


17/28


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

($)


Sensitivity to Weld Length in Al Design for Body Side Outers

Aluminum

1 Piece

Baseline


50 70 90 110 130 150

Weld Length (in)

$50

$60

$70

$80

$90

$100

Cost($)


Sensitivity to Aluminum Price for Body Side Outers

Aluminum

Baseline


$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)


18/28


Aluminum Spaceframe Design Layout


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


Cost Results: Aluminum Part Forming Processes

Extrusion

Die Casting

Stamping

$0

$5

$10

$15

$20

$25

Cost/lb($)


19/28


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:


Production Cost Results

Annual ProductionVolume20,000



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


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


20/28


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.


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


21/28


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?


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


Trim

CureReactionInjectionMold

Trim

Thermoform

CutReinforcementMaterial

Foam Core /PreformSubassembly

ResinTransferMolding

Trim/Inspect

Preforming

Foam Core Molding

Resin TransferMolding


22/28


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


Resin Transfer Molding Cycle Time Estimation

Cycle Time = Preparation Time + Fill Time + Cure Time

Preparation Time:

Fill Time:

Cure Time:


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,


23/28


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?


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


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


24/28


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


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)


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


25/28


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


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


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)


26/28


Cost per Kilogram Saved (Relative to Steel Base Case)

5 20 35 50 65 80 95 110 125 140


($5)

($4)

($3)

($2)

($1)

$0

$1

$2

$3

$4

$5

CostperK

gSaved

RTM Glass

RTM Carb

RTM Ca/Gl

SMC


5 20 35 50 65 80 95 110 125 140


$50

$100

$150

$200

Steel

RTM

SMC 5%

SMC 30%

Steel: 9 parts

RTM: 2 Parts

SMC: 1 Part


5 20 35 50 65 80 95 110 125 140


$400

$500

$600

$700

$800

Steel

RTM

SMC 5%

SMC 30%

teel: 57 parts

RTM: 2 parts + 20 inserts

SMC: 9 parts + 20 inserts


27/28


Hybrid Vehicle Scenarios

515

2535

4555

6575

8595

105115

125135

145


$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


Hybrid Vehicle Scenarios

0 50 100 15056 92


$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


Hybrid Vehicles: Cost per Kilogram Saved

5 20 35 50 65 80 95 110 125 140


($5)

($4)

($3)

($2)

($1)

$0

$1

$2

$3

$4

$5

CostperKgSaved

Hybrid 5%

Hybrid 30%

RTM

SMC


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Total cost of composites BIW is competitive with steel at low production volumes (

future of automotive body materials

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