Manufacturing – Casting methods - European Aluminium Association

1.12.2 Pattern making & cluster assembly
Pattern making. The initial material required for pattern making is expandable polystyrene
(EPS). First step in the LFC-process is the pre-expansion of EPS beads.
After maturing the beads are blown into a mould forming the pattern sections. The mould is
then steamed to expand the beads further and tightly fill the cavity of the mould. Hot steam
and expansion of the beads causes them to weld together.
Cluster assembly. Complicated parts including undercuts and hidden cavities cannot be
moulded in one working step, but are assembled from pattern segments into a final pattern.
Joining techniques used are gluing, heated platen welding and plugging. In order to increase
the efficiency of the total process several patterns are combined into a cluster and supplied
with a common gate system, also made of EPS.
Pre-expansion unit
Source: LWF/ZVG Paderborn
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