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Auto/Steel PartnershipLightweight Front End Structure –

Hydroform Solution and Cost Analysis

Sanjay ShahGeneral Motors Corporation

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AUTO/STEEL PARTNERSHIP MEMBERS

John Catterall (GM) / Jody Shaw (USS) – Project Leaders

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Background

Auto/Steel Partnership project on Lightweight Front End Structure using AHSS

Motivation for using AHSS:- Mass avoidance - Adequate performance- Lower overall cost

Phase I : Optimize ULSAB design using AHSSPhase II : Optimize Front Rail and Bumper system

of ’04 high volume production vehicle - Stamping Based

Phase III : - Hydroform Based

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Donor Vehicle Baseline Design

Components 27 stampingsSteel Grade BH210 & HSLA340Weight 39.2 kg

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Phase II : LWB Stamped Solution

Components 12 stampingsSteel Grade DP780Mass 30.5 kgMass Savings 22.4%

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Phase III : Hydroform Design Approach

- Use same approach for optimization of Front Rail and Bumper Beam using available packaging space as in Phase II - LWB Stamped design

- Meet all the performance objectives 35 mph NCAP frontal crash, 40 mph IIHS frontal off-set crash, static stiffness and dynamic stiffness

- Optimize design for mass by incrementally pushing manufacturing frontier (expanding knowledge)

- Follow general tube hydroforming mfg. guidelines (% expansion, bend radius, corner radius etc..)

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Solstice Structure

DP590T, 1.8mm Hydroform Rails

Current State of Art for Hydroforming – in production

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Hydroform Solution

Max tube expansion 8%

Min cornerradius to 10mm

Min bend radius to tube diameter ratio of 2.5

Max tube expansion 8%

Min cornerradius to 10mm

Min bend radius to tube diameter ratio of 2.5

Bumper - DP980 to Martensitic 1300Hydroform – DP600 to DP800

- Optimize using DoE for Gage and Grade

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Bumper (Inner and Outer)Mart 1300 1.2mmMart 1300 1.0mm

Rail ADP800 1.2mmDP800 1.3mm

Rail BDP800 1.3mmDP800 1.3mm

Rail CDP800 1.4mmDP600 1.4mm

Rail DDP800 2.0mmDP800 2.0mm

Rail EDP800 1.4mmDP600 1.4mm Rail F

DP800 1.3mmDP600 1.3mm

Tube Diameter (O.D.) = 108.6mm

Design 2 - Progressive CollapseSteel Grade DP800Mass 28.8 kgMass Savings 26.5%

Design 3 – Non-Progressive CollapseSteel Grade DP600 and DP800Mass 26.8 kgMass Savings 31.8%

Hydroform Solution

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Crash Simulation

35 mph full frontal NCAP – Design 2

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35 mph NCAPDesign 2

SIMULATION RUN 35mph NCAP

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35 mph NCAP Design 3

SIMULATION RUN 35 mph NCAP

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Crash Simulation Results

Crash Target Satisfied

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Stiffness Results

Design

Static Torsional(Nm/deg)

StaticBending(N/mm)

DynamicTorsional

(Hz)

DynamicBending

(Hz)

Baseline 21,002 12,639 21.1 24.4Design 2 20,482 12,399 24.8 26.3Design 3 20,454 12,387 24.9 26.4

Stiffness

Stiffness Target Satisfied

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Hydroform Solution - Mass Sensitivity

- Mass sensitivity of Bumper & Hydrof. Frt. Rail to mass of vehicle- By reducing mass of donor vehicle by 20%, additional mass savings of 12% to 18% in hydrof. rail & bumper system

Rail ADP800 1.0mm

Rail BDP600 1.4mm

Rail CDP800 1.3mm

Rail DDP600 1.4mm

Rail EDP600 1.3mm Rail F

DP600 1.0mm

Hydroform Design Option 2Mart 1300 1.0mmBumper (Inner and Outer)

Rail ADP800 1.0mm

Rail BDP600 1.4mm

Rail CDP800 1.3mm

Rail DDP600 1.4mm

Rail EDP600 1.3mm Rail F

DP600 1.0mm

Hydroform Design Option 2Mart 1300 1.0mmBumper (Inner and Outer) Mass Reduction

Design B =15.6kg (39.8%)

Mass = 23.6 kg

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Expanding Mfg. Systems with current challenges:

- Tubes from AHSS (DP800 and DP600)- Tubes with D/t > 70 (thin wall tubing)- Tailored tubes (Soudronic, Mubea,

Thyssen -Krupp, Noble International, Corus etc.)

Manufacturing Frontier

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0,000,200,400,600,801,001,201,401,601,802,00

0 200 400 600 800 1000 1200 1400

Rohrlänge in mm

Wan

dstä

rke

in m

m

HSLA420 TRBflexible rolled

1.0 > 1.6 > 1.8 > 1.6 > 1.0 > 1.4 > 1.0

tube length in mm

Shee

t met

al th

ickn

ess

in m

m

Flexible Rolling of Tailor Rolled Blanks

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Tailored Tubes

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Volvo C70 A pillar – Hydroform

Variable Wall and Diameter

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Expanding Mfg. Systems with current challenges:

- Tubes from AHSS (DP800 and DP600)- Tubes with D/t > 70 (thin wall tubing)- Tailored tubes (Soudronic, Mubea,

Thyssen -Krupp, Noble International, Corus etc.)

Manufacturing Frontier

- Hydroforming of AHSS, Tailored Tubes

- Joining Methods for closed section partsArc welding, Laser welding, Single Sided Spot Welding, Projection Welding, Adhesive, Mechanical Fastening etc..

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Assembly

RailFront Cradle Mount

Rear Cradle Mount

Torque Box(not shown)

Front & RearPanel Skirt

Tie Bar Extensions

Bumper

Welding to floor(MIG or spot)

Components and Joining : MIG welding chosen as primary method

Stamped rail shown

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888

10------

9 .130 .400 .40

796 143675

888

10------

9 .130 .400 .40

796 143675

42.52

---

6.39

5.36

30.77

Weight(kg)

---

35

1

2

32

# of Parts

Hydroformings

TOTAL

Rollformings

Tailored Blanks

Stampings

------

31.6520

------

18.906

12.7514

Weight (kg)

# of Parts

12

2

---

---

10

# of Parts

20.60

28.85

---

---

8.25

Weight (kg)

Stamped Base Hydroform

BoltsRivets

MIG Welds (m)Spot Welds

BoltsRivets

MIG Welds (m)Spot Welds

888

10------

9 .130 .400 .40

796 143675

888

10------

9 .130 .400 .40

796 143675

42.52

---

6.39

5.36

30.77

Weight(kg)

---

35

1

2

32

# of Parts

42.52

---

6.39

5.36

30.77

Weight(kg)

---

35

1

2

32

# of Parts

Hydroformings

TOTAL

Rollformings

Tailored Blanks

Stampings

Hydroformings

TOTAL

Rollformings

Tailored Blanks

Stampings

------

31.6520

------

18.906

12.7514

Weight (kg)

# of Parts

------

31.6520

------

18.906

12.7514

Weight (kg)

# of Parts

12

2

---

---

10

# of Parts

20.60

28.85

---

---

8.25

Weight (kg)

12

2

---

---

10

# of Parts

20.60

28.85

---

---

8.25

Weight (kg)

Stamped Base Hydroform

BoltsRivets

MIG Welds (m)Spot Welds

BoltsRivets

MIG Welds (m)Spot Welds

Components and Joining

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Cost Modeling Approach

General Inputs

AccountingData

ProductionVolumes

Fabrication& Assembly Process Data

MaterialPrices

StampingPress

Information

AssemblyMethod

Data

Body Results

Cost SummaryBy Hood

Stamping CostSummary per Part

Assembly Summary per Subass’y

Cost Results

Cost SummaryBy Front

End

Cost Summary per Part & by Process

Assembly Summary per Subass’y

Cost SummaryBy Front

End

Cost Summary per Part & by Process

Assembly Summary per Subass’y

Body InputsStampingPartDescription

StampingData

BlankingData

AssemblySubassemblyList

Joining Methods

HydroformingPartDescription

HydroformData

TubeData

Body CalculationsStampingCost Breakdowns Process Data

AssemblyCosts for EachJoining Method

Predicted LineDescription

HydroformingCost Breakdowns Process Data

General Inputs

AccountingData

ProductionVolumes

Fabrication& Assembly Process Data

MaterialPrices

StampingPress

Information

AssemblyMethod

Data

General Inputs

AccountingData

ProductionVolumes

Fabrication& Assembly Process Data

MaterialPrices

StampingPress

Information

AssemblyMethod

Data

Body Results

Cost SummaryBy Hood

Stamping CostSummary per Part

Assembly Summary per Subass’y

Cost Results

Cost SummaryBy Front

End

Cost Summary per Part & by Process

Assembly Summary per Subass’y

Cost SummaryBy Front

End

Cost Summary per Part & by Process

Assembly Summary per Subass’y

Body Results

Cost SummaryBy Hood

Stamping CostSummary per Part

Assembly Summary per Subass’y

Cost Results

Cost SummaryBy Front

End

Cost Summary per Part & by Process

Assembly Summary per Subass’y

Cost SummaryBy Front

End

Cost Summary per Part & by Process

Assembly Summary per Subass’y

Body InputsStampingPartDescription

StampingData

BlankingData

AssemblySubassemblyList

Joining Methods

HydroformingPartDescription

HydroformData

TubeData

Body InputsStampingPartDescription

StampingData

BlankingData

AssemblySubassemblyList

Joining Methods

HydroformingPartDescription

HydroformData

TubeData

Body CalculationsStampingCost Breakdowns Process Data

AssemblyCosts for EachJoining Method

Predicted LineDescription

HydroformingCost Breakdowns Process Data

Body CalculationsStampingCost Breakdowns Process Data

AssemblyCosts for EachJoining Method

Predicted LineDescription

HydroformingCost Breakdowns Process Data

Camanoe Associates

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Total Cost

At 225,000 units/year

II

III

- Greenfield approach, Process based costing,, Dedicated Tooling cost, % Equipment Cost

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Cost Analysis

Dedicated Tooling Investment

Stamped Base HydroformStamped Base Hydroform

$5.0M$4.1M$4.4MAssembly

---$8.7M$2.4MTailored Blank Stampings

$19.5M

---$0.2M

$12.5M

$15.2M$20.6MTOTAL

$5.1M---Hydroformings------Rollformings

$5.1M$7.8MStampings

$5.0M$4.1M$4.4MAssembly

---$8.7M$2.4MTailored Blank Stampings

$19.5M

---$0.2M

$12.5M

$15.2M$20.6MTOTAL

$5.1M---Hydroformings------Rollformings

$5.1M$7.8MStampings

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Cost Analysis

Variable and Fixed CostStamped Base HydroformStamped Base Hydroform

$123$101$111TOTAL FIXED COST

*Includes labor and energy

$82$102$103TOTAL VARIABLE COST

$40$37$40Other Fixed Costs#

and overhead#Includes building, maintenance,

$39$46$54Other Variable Costs*

$214

$23$48

$49

$205$203TOTAL UNIT COST

$18$24Tooling Cost$65$40Equipment Cost

$43$56Material Cost

$123$101$111TOTAL FIXED COST

*Includes labor and energy

$82$102$103TOTAL VARIABLE COST

$40$37$40Other Fixed Costs#

and overhead#Includes building, maintenance,

$39$46$54Other Variable Costs*

$214

$23$48

$49

$205$203TOTAL UNIT COST

$18$24Tooling Cost$65$40Equipment Cost

$43$56Material Cost

II III

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Detail Report at http://www.a-sp.org

Thank You

Hydroform based structure can provide mass and cost benefit

Lightweight Front End Structure

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• The work was completed by a team effort between the Auto/Steel Partnership members and its Partners.

Acknowledgment

red cedarTECHNOLOGY