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A L U M I N I U M I M A U t o M o b I L
Fig. 5: Initial simulation of SLC side panel in aluminium
ment. It is obvious that the new simulation
is safer (more green area). Some
critical areas disappeared and some
have become less critical. This can
also be observed when comparing
the FLD plots. The red area is clearly
shifted from critical deep drawing on
the left side to the middle section. One
option to go forward is to further optimise
the deep drawing process with
simulation in order to reduce the red
zones. However, this middle zone of
an FLC is typically an area that is also
strongly influenced by friction and
typically friction is one of the parameters
that can easily be controlled in
prototyping.
Therefore, this is the point where
simulation shows that the side panel
is feasible in aluminium. The proposed
layout of the deep drawing process
behind the simulation from Fig.
6 is taken as the starting point for the
prototype toolmakers. The part being
produced now is perfect. Thus simulations
are used as a last but necessary
step to describe conditions of the deep
drawing process for the manufacturability
of aluminium parts. Aluminium
makes an important contribution to
this multi-material concept due to the
favourable combination of low density
and low production costs, with
aluminium solutions easily applicable
for high volume production.
Extrusions
Another wide field of aluminium solutions
and applications is opened by
making use of the well established
technology of aluminium extrusions.
Here quite complex shapes of profiles
can be achieved allowing innovative
light weight design with integrated
functions. In Europe complete new
and flexible car concepts (e. g. the
aluminium space frame) and complex
sub-structures (e. g. in chassis
parts, bumpers, crash elements, air
bags, etc.) have been developed using
aluminium extrusions. Their high potential
for complex design and functional
integration is most suitable
for cost-effective mass production.
Medium strength AA6xxx and high
strength AA7xxx age hardening alloys
are used, since the required quenching
occurs during the extrusion process.
Formability and final strength
is controlled by subsequent heating
for age hardening. Extrusions are applied
for bumper beams and crash elements/boxes,
also in the SLC car.
Castings
The highest volume of aluminium
components in cars are castings,
such as engine blocks, cylinder heads
and special chassis parts. The substitution
of cast iron engine blocks continues.
Even diesel engines, which
continue to gain a substantial increase
in market share in Europe now, are
being cast in aluminium where, due
to the high requirements on strength
and durability, cast iron has generally
been used. However, progress
in aluminium alloy development (Al-
Si-Cu-Mg-Fe-type) and new casting
techniques came up with improved
material properties and functional
integration that enables aluminium
to meet the requirements. Aluminium
castings are also gaining acceptance
in the construction of space frame,
axle parts and structural components.
Complex parts are produced by special
casting methods that ensure optimal
mechanical properties and allow
enhanced functional integration
[5]. For high pressure die cast HPDC
new AlSiMgMn alloys have been developed
with enhanced strength and
ductility combination. In the SLC
project structural parts in the wheel
house architecture have been designed
using advanced aluminium die
cast with an integrated striker plate.
Summary and Conclusions
Due to its low weight, good formability
and corrosion resistance, aluminium
is the material of choice for many automotive
applications such as chassis,
autobody and many structural components
[13]. Aluminium alloys tailored
by suitable variations in chemical
composition and processing best fit
many requirements, like the non-heat
treatable Al-Mg alloys used in chassis
optimized for superb resistance
against intercrystalline corrosion and
concurrent high strength or the heat
treatable AlMgSi alloys for extrusions
and autobody sheet modified for improved
age hardening response during
the automotive paint bake cycle.
32 ALUMINIUM · 9/2009