Manufacturing – Casting methods - European Aluminium Association

1.12.4 Pouring & finishing
Simplified decomposition of EPS during form filling
Source: LWF/ZVG Paderborn
Pouring: During the filling process the molten metal flows via the gate system into the EPSpatterns,
which is gasified, filling up the cavity and replacing exactly the pattern geometry.
During this stage it is important to avoid turbulences, support the casting cavity wall and to
realise a progressive elimination of the foam pattern. The gas originating from EPS
decomposition permeates the coating layer and escapes into the sand, possibly supported by
an external vacuum (see schematic fig. above). Form filling velocity and type of metal flow,
i.e. laminar or turbulent, determine the part's quality by influencing the amount of oxide
inclusions and porosity. Specifically, the following sets of parameters have to be tuned to
each other:
permeability of coating,
optional external vacuum,
metal temperature,
EPS-pattern density and type of adhesive,
geometry of the gating / riser system and of the patterns.
Dumping, quenching and trimmig:
After solidification of the casting, the sand can be removed from the flask and be prepared for
the following moulding. Clusters are quenched and knocked-off from the gate system. The
castings are purged and controlled w.r.t. defects. In many applications the castings don't
require any further mechanical finishing.
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