CPT International 02/2016

K CASTING TECHNOLOGY
subjected to extreme stress. In the investigations,
a dynamic casting technique,
which fills the cavity in a controlled
tilting movement with the
feeder (Figure 1), proved to be clearly
the most preferred method.
Especially in the production of modern,
highly stressed cylinder heads,
classical low-pressure die casting has
been reaching its limits because it fails
to achieve the required fine-grained
microstructure in the calottes of the
combustion chambers. Therefore ways
had to be found how to expand the
potential of existing low-pressure die
casting equipment by a process adaptation
that would require only minimal
capital investment. This was achieved
by pouring the molten metal directly
from the low-pressure pouring furnace
into the pouring basin, as schematically
shown in Figure 2.
Versus a process using a bale-out furnace
with an undocked basin, the newly
introduced solution means just a few
seconds of additional cycle time. At the
same time, it provides the possibility of
handling greater casting weights and
the benefit of having less mechanical
elements near the hot die. This solution
Dynamic Static
Bottom poured Top poured Low-pressure casting
Static casting
Oxide films --
DAS -
Directional solidification -
Dynamic tilt casting
Oxide films ++
DAS +
Directional solidification +
*) unless formed during basin filling or in the riser tube
Static casting
Oxide films ---
DAS ++
Directional solidification +
Dynamic tilt casting
Oxide films *) +++
DAS +++
Directional solidification +++
Low-pressure feeding
Oxide films *) +++
DAS ---
Directional solidification ++
Gravity feeding
Oxide films *) +++
DAS +
Directional solidification +
Figure 1: Comparison of applied mold filling and feeding principles (Graphics:
Smetan Engineering)
would also be an option for the production
of larger cylinder heads and for engine
blocks. However, the most important
benefit of this approach is that it
requires only minimally invasive measures
to transform existing low-pressure
die casting capacities used for the production
of cylinder heads to modern,
future-oriented casting equipment.
The CAD image in Figure 3 shows
the equipment design implementing
this solution. The pouring basin
is being filled from below with a perfectly
clean and oxide-free alloy directly
from the low-pressure pouring
furnace, without causing any disturbing
turbulences. This requires a special
geometrical design of the docking
Figure 2: Turbulence-free filling of the pouring basin from a low-pressure pouring furnace for dynamic tilt casting
(schematic illustration of design details).
24 Casting Plant & Technology 2/2016