CPT International 4/2019

PRESSURE DIE CASTING
Photo: ??
Light-weight castings can be
joined by means of latest laser
welding methods to manufacture
highly loadable and economically
efficient structural components.
Castings for lightweight
engineering
Cast iron and aluminium alloys as alternatives for
thin-section steel castings.
Wolfgang Knothe, Franken Guss, Kitzingen
The urgent call for light-weighting
solutions in automotive engineering
entails two key requirements:
reliable and consistent material properties
of the component, and a design suitable
for the expected in-service stress
load of the component. In other words,
the service life of a component depends
to a large extent on the component
design. This is where casting technology
comes in because here both the geometry
of a component and the material
properties evolve in one and the same
process. Additionally, thanks to the high
degree of process automation, large
series production is assured.
Steel casting has its limits, above all
for economic reasons. Steel‘s very high
melting and casting temperatures, its
high shrinkage rates and the complexity
of steel heat treatments are the main
causes for this. The development of
advanced materials, such as ductile iron
and T6 aluminium alloys, has overcome
these constraints. This does not mean
that the importance of aluminium as
the classical light-weighting material
has decreased. While ductile iron and
steel alloys have similar properties, the
melting temperature of ductile iron is
lower by 400 K, giving it excellent teeming
properties. Meanwhile, a number
of highly loaded structural parts which
used to be exclusively made of steel
have been replaced by ductile iron castings.
Ductile iron castings are characterized
by the following features:
a b c
Figure 1: Light-weight ductile iron castings. a) tubular cross member, b) differential cage, c) pressure plate.
a b c
Figure 2: Light-weight aluminium castings. a) sill plate, b) bearing bracket for front suspension, c) steering support.
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