Aluminium Structured Vehicles:

Myths and Realities

Geoff Scamans Innoval Technology

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Environmental performance of transport

120
CO2
110
Index (1990 = 100)

100
90 Particulates
Acidifying
80
substances
Ozone
70
precursors
60
Source: Defra 2005
1990 1992 1994 1996 1998 2000

http://themes.eea.eu.int/Sectors_and_activities/transport

Source: Tyndall Centre for Climate Change Research

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Weight and CO2 Reduction

• The weight of a vehicle is crucial in terms of its relative CO2 performance

• The weight of cars is on the increase (by 60% over 25 years)
• The simplest method to improve fuel economy is to reduce vehicle weight
• Aluminium has approximately one-third the density of steel. When aluminium
replaces steel only 1 kg is required to perform the same function as 2kg of steel
• 5- 10% fuel savings are realised for every 10% reduction in vehicle weight
(studies by Ford, BMW, Argonne, Ross, EAA, International Aluminium Institute)
• Fuel savings, due to weight reduction, can more than offset, over the life of the
vehicle, the initial higher materials cost of using aluminium
• An aluminium BIW is typically 40 to 45% lighter than an equivalent steel structure
• The end of life value of the aluminium BIW structure is high

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Aluminium Structured Vehicles

Honda NSX 287 g/km

BMW Z8

Aston Martin Vanquish 396 g/km

Rolls Royce Phantom 385 g/km

Lotus Elise 177 g/km

Honda Insight 80g/km

Lamborghini Gallardo 2003 450 g/km

Ferrari 612 Scaglietti 2004 475 g/km

GM EV1 0 g/km 134kg BIW

• aluminium is used for performance not fuel efficiency

The average CO2 emission from 2.6 million new cars in the UK in 2004 was 171.4 g/km. Only 481 cars were sub 100 g/km
Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Comparison of CO2 Emissions

3.0 L cars (VW Lupo/Audi A2)

hybrid car - Honda Insight

hybrid car - Toyota Prius

mid-size diesel car

SMMT: UK New Car Registrations by CO2 Performance, April 2005

mid-size petrol car

heavy diesel car

heavy petrol car

Sports Utility Vehicle (SUV)

0 50 100 150 200 250 300

CO2 emissions g/km
The UK Government has set the target that cleaner cars (defined as ‘low carbon’; <100g/km) should represent 10%
of all car sales by 2012 (DfT 2002).

http://themes.eea.eu.int/Sectors_and_activities/transport

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Audi A2 1.2 TDi

Honda Insight 80g/km

• First 4 door 3 litre car (2.99 litres/km)

• Compared with the A2 1.4 TDI, the suspension is over 80 kilograms lighter. The axle mounting
frame, control arms and spring struts are made from aluminium instead of steel. The brake
calipers on the front disc brakes and the brake drums at the rear are also aluminium
• Lightweight forged aluminium wheels
• Lighter than 1.4 TDI by 135 kilograms, and weighs 825 kilograms.
• The three-cylinder TDI has a light-alloy cylinder head and an aluminium engine block. The weight
saving is 16 kilograms. At 100 kilograms, the 1.2 litre TDI is one of the lightest passenger-car
diesel engines
• Not in production??

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Hybrid Vehicles
Toyota Prius Honda Insight

104 g/km 80g/km

Steel body with Aluminium bonnet and tailgate All aluminium body 1847 lbs (840 kg) Aluminium
2765 lbs (1257 kg) 244,441 units by Nov 2004 monocoque. 1.0-liter, 3-cylinder gasoline engine with
an ultra-thin electric motor. Similar weight and CO2 to
Audi A2 1.2 TDI

US Hybrid Sales in Dec 2004

Toyota Prius 6287
Honda Civic 2116
Honda Accord 1061
Honda Insight 8
Ford Escape 969

Total 10,441

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

1925 Alcoa Pierce Arrow

•In 1920 Alcoa sponsored the construction of several all-
aluminium cars designed by Laurence Pomeroy and built
by Pierce Arrow. The body structures were built up from a
combination of aluminium castings and stampings fitted
with aluminium panels
•As early as 1913, NSU produced the 8/24 car with a body
entirely made of aluminium.

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Description: Space Frame

SOP: 1994
Weight: BIW + closures: 249 kg
Number of parts: 334
Volume (cars/year): 16,000
Joining methods:
· Resistance spot welds: 500
· Clinches: 179
· Self piercing rivets: 1100
· MIG welds: 70 m
Materials/parts:
Extrusions: 47 (14%)
Castings: 50 (15%)
Stampings: 237 (71%)

weight saving 500 kg (43%)

231 to 355 g/km

Audi A8 (1994)

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Description: Space frame:

SOP 1999
Weight: BIW (121 kg) + closures 153 kg
Number of parts: 225
Volume (cars/year): scheduled 70,000
Joining:
Self piercing rivets: 1800
MIG weld: 20 m
Laser weld: 30 m
Materials/parts:
Stampings: 183 (81%)
Extrusions: 22 (10%)
Castings: 20 (9%)
Weight saving 231 kg
119 to 144 g/km (1.2 TDI 80 g/km)
165,000 vehicles built

Audi A2 (1999)

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Jean Albert Gregoire, Rene Panhard and Aluminium Francais

1934, Aluminium Francais Gregoire (AFG) cast aluminium frame.

1946, VP2 launched as the Dyna (560 kg)

1946, Dyna X

1948, Dynavia prototype

1953-59, Dyna Z (by 1957 steel replaced aluminium)

http://www.voitures-d-ingenieurs.com/biography.htm
Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Spot welded aluminium body on a

sheet aluminium floor reinforced with
extruded tubes and side sills. The
alloy used was similar to AA5754.
Panhard manufactured over 50k
aluminium intensive cars.

Dyna Panhard (1954)

The first production car to use aluminium as a structural material for

its body shell. It was powered by a diminutive 850 cc two-stroke
engine, weighed only 629 kg and could carry six people.

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

BL Metro AIV
Six AIV replica British Leyland
Metros were built in 1983. The
sheet moncoque body structure
was built from AA5251 sheet
while the closure panels
consisted of standard steel
components.

Bertone Fiat X1/9 AIV

Five AIV replica Bertone Fiat

X1/9s were built in 1986 using
AA5251 sheet for the
monocoque and AA6010 for
the closure panels.

Ford Taurus/Sable AIV

A build of 40 Mercury Sable
AIVs was completed in 1993
using AA6111 sheet for closure
panels and AA5754 sheet for
the monocoque structure. The
structure was not redesigned
yet a weight saving of 46%
was achieved.
Steel Aluminium Weight Saved %Change
Body Structure (kg) 271 145 125 46
Hood, deck & fenders 41 17 24 58
Front and rear doors 60 36 24 40
Total body-in-white 372 199 173 47
Torsional rigidity (Nm/rad) 575 855 +49
Total vehicle 1488 1315 173 11.6

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Jaguar XJ Jaguar XJ8 L

Jaguar XJ LWB mpg ratings
City
18
Highway Combined
28 22
Jaguar Vanden Plas 18 27 21
Jaguar Super V8 17 24 20

Description : Mercedes S500

Mercedes S600
16
12
22
19
18
15
BMW 745 Li 18 26 21
Sheet unibody structure Source: US Environmental Protection Agency

SOP : 2003
Weight : painted BIW 295 kg
Volume (car / year) : 30,000
Materials / parts :
Castings : 15 ( 5 %)
Extrusions : 22 (7 %)
Stampings : 273 (88 %)
Curb weight: -200 kg
249 to 299 g/km Joining methods :
Adhesive bonding (114 m)
Self piercing rivets (3195)
Clinches : 110
MIG welds : 2 m
Blind rivets : 22

Special characteristics :
· 40 % lighter than steel
· 60 % stiffer than predecessor
Suitable for high volume
production (> 100,000
units per year)

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Myths

• Aluminium is difficult to spot weld reliably and consistently

• Bonding of aluminium requires high modulus adhesives and aerospace

quality pretreatment systems

• Aluminium sheet requires surface texturing to enhance formability

• Aluminium sheet requires a stabilisation treatment

• Aluminium intensive vehicles require purpose built finishing lines

• Aluminium automotive sheet is too expensive for the production of

affordable volume production vehicles

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Spot Welding of Aluminium

• Following the introduction of tip dressing for spot welding of galvanised
steel it was shown that aluminium sheet could be spot welded reliably
without a progressive degeneration of joint performance with electrode life
using a similar simple tip dressing technique.
• A spot welding cell to demonstrate this technique has been set up at
Warwick University

HAZ Nugget

1 mm

Parent Transition zone

Nugget

Transition zone

HAZ
Parent
douglas.boomer@innovaltec.com

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Adhesive Bonding of Aluminium

• Aluminium may be bonded with a wide range of structural adhesives
without a detrimental effect on vehicle stiffness
• A wide range of simple chrome-free pretreatments will provide perfectly
adequate bond durability

Influence of Adhesive Elastic Modulus on Vehicle Stiffness

100%

95%
Relative Stiffness

90%
Adhesive Relative Stiffness
Bending
E/E_XD4600 Bending Torsion
1.00 100% 100% Torsion
85% 0.67 99.5% 99.6%
0.33 98.2% 98.4%
0.10 94.2% 95.0%
80% 0.00 79.9% 83.6%

75%
0.00 0.20 0.40 0.60 0.80 1.00
Elastic Modulus Value Relative to XD4601 (E = 3000MPa)
dubravko.nardini@novelis.com
Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Surface Texture and Stabilisation

• Textured sheet requires a lower coat weight of lubricant compared to a mill
finished surface for acceptable deep draw capability. With waxy lubricants
there is no measurable difference in formabilty

• Stabilisation treatment is unnecessary for AA5754 sheet for structural

applications

mill finished EDT Electrograined

250µm

Topochrome 1 Topochrome 2 Std EDT

theresa.warrender@novelis.com
Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Finishing
• Aluminium intensive vehicles can be finished on steel lines provided that
zinc phosphating is minimised and the surface is passivated/pretreated
properly after phosphating
Alloy AA6111 250 hour Lockheed corrosion test
Low Fluoride

High Fluoride

Zr/Ti fluoroacid

Unground area Ground area 10 mm

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Relative cost of Aluminium Sheet vs Steel Sheet

• Aluminium sheet can be produced by continuous casting and by the high
level recycling of process scrap and end of life vehicle structures

Mark White, Automotive Aluminum Technology Forum, Detroit, 16 November 2004

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Twin Belt Casting of Aluminium Sheet

Twin belt cast AA5754 structural automotive sheet is available from Commonwealth Aluminum

Andrew M Sherman, ICAA 7, April 10, 2000

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Relative Cost and Performance

Strategies for Aluminum in the Auto Body Ashish Kelkar May 9, 2000

Andrew M Sherman, ICAA 7, April 10, 2000

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Cost Modelling of Aluminium Sheet Production

Conventional
Auto-sheet route

Twin Roll Cast

Auto-sheet route

andy.darby@innovaltec.com
Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Developments in Twin Belt Casting

Alcan has licensed its latest

generation Flexcaster thin slab
twin belt casting technology for
automotive sheet production by
NLM in Japan. 6-7mm slab from
the belt caster is cold rolled to
final gauge

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Twin Roll RheoCasting (TRRC) of Aluminium Sheet

BCAST (Brunel University) has developed rheocasting technology that could

enable the production of structural automotive sheet alloys like AA5754 to be
made a low cost using a twin roll caster
Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Summary
• Aluminium intensive vehicle structures can make a dramatic contribution to the
reduction of CO2 emissions from vehicle transport
• Aluminium intensive vehicles are an alternative to hybrid drive systems in terms of
CO2 emissions
• Aluminium sheet can be cost competitive with steel sheet provided that vehicle
running costs are considered and credit is given for the high value of the vehicle
structure at the end of life
• Continuous casting of aluminium sheet for automotive structural applications will
narrow the price gap between aluminium and steel
• Aluminium can be formed, spot welded, bonded and finished with conventional
technologies
• Aluminium sheet can be considered as lightweight steel for the purpose of high
volume car making

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005
Aluminium Vehicle Structures: Myths and Realities

Low CO2 cars are not using the aluminium advantage

If the lowest CO2 emitting vehicles in each segment were only bought within the segment then average CO2
emissions would fall by 32 per cent to 117g/km.
SMMT: UK New Car Registrations by CO2 Performance, April 2005

Light Metal Surface Science Annual Conference, Trondheim, 15-16 June 2005