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Steel
vs. Aluminum: Cost Comparison
The figure
below shows common metallurgical grades undergoing a pre-strain of 2%
and typical automotive paint bake cycle on the left compared to their
prospective cost index shown on the right. Pricing for steel
grades is based on seven combined typical market sources and the
ULSAB-AVC cost model. Aluminum pricing was gathered based on 2002
publications from the MIT Material Systems Lab and typical market
information, such as the American Metal Market (2002-2003).
Also regarding
material cost related to vehicle production, according to Joe Clark from
the Massachusetts Institute of Technology, cited from the January 1997
issue of MIT Technology Review:
|
Material
costs |
| |
Steel
Unibody |
Aluminum
Space
Frame |
Aluminum
Unibody |
Low
production
(less than 20,000/yr.) |
$5,800 |
$4,500 |
$7,200 |
Medium Volume
(approximately 100,000) |
$2,500 |
$2,800 |
$3,600 |
Volume of 300,000
(common to most platforms in North America) |
$1,400 |
$2,400 |
$2,000 |
Higher Volumes
(300,000 to 1,500,000/yr.) |
Steel
becomes even more cost effective when compared to the space frame aluminum
and unibody concepts! |
-
The
costs are driven by: process cycle times, equipment
utilization, capital investment, and raw material cost only
($.35/lb. for steel vs. $1.50/lb. for aluminum).
-
If all
the other factors such as recyclability, scrap due to less
formability of aluminum, the superior weldability of steel, the
cost advantages for steel would be shown even greater.
In relation
to the overall vehicle assembly process, MIT has also undertaken
numerous studies on the subject of cost assessment. Shown below is
their results from a study comparing the all aluminum Audi A2 to both a
VW Lupo and a Hybrid Lupo.
These two
graphs represent both the materials cost differential between the VW
Lupo (steel), Lupo (Hybrid - Mg liftgate/SMC skin panels), and the all
aluminum Audi A2. As shown, both for the raw material cost and
assembly costs, steel at all volumes, is much more cost effective (over
$1000/vehicle less).
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