CPT International 01/2015

Automatic Seiatsu molding machine type EFA-S 8,5
Pattern shuttle at the automatic molding machine
others, one advantage for the exchange
of the molding machine was
the low degree of adaptation required
in the foundation area.
Furthermore, the inside dimension
of the flask was increased from 2500
x 1600 mm to 2630 x 1700 mm while
maintaining the former outside dimension;
cope and drag are 600 mm
high each. This enlargement opens
up the opportunity to the foundry to
mold bigger patterns and thus to extend
the variety of products.
In addition, the automatic molding
machine type EFA-S 8.5 was equipped
with an automatic pattern change
( Figure 2). In running operation, the
following patterns can be prepared and
exchanged automatically which makes
the pattern change cycle shorter. The
arrangement of these preparation places
increases the accessibility at the stations;
so-called safety lifting gates ensure
a safe sequence during the pattern
change.
To improve the mold quality
( ), the foundry can, after the
modernization from jolt-squeeze
molding process, avail themselves of
the two-step airflow-squeeze molding
process Seiatsu (in combination with
squeezing from pattern side as an option)
– the currently most common
molding process in tight-flask green
sand molding plants. The two steps of
the molding process consist on the one
hand of the Seiatsu airflow that penetrates
the sand pre-dosed by the movable
sand hopper, aerates it and compacts
it by exiting through the vent
holes in the pattern (and/or the pattern
bolster) on the pattern side. In
addition, the second step provides a
hydraulic pressing of the sand back.
Here an homogeneous mold strength
is in the focus of the process control
to achieve optimum degassing during
the casting process (see lead picture).
In case of this project, the molding
machine is equipped with a so-called
multi-ram press that optimally adapts
the process of pressing to the pattern
geometry. Also many of the sand
touching flaps and ducts in the sand
dosing hopper are fitted with highly
porous plastic sheets which create
ventilation and an air cushion between
the molding sand and hopper
wall. This reduces wear, the sand does
not stick and thus creates a process reliable
sand filling process.
Furthermore, the function „squeezing
from pattern side“ enables an optimization
of the sand compaction at
the flasks’ limits by a levelling frame
that can be activated, especially in case
of patterns with an unfavourable ratio
of casting and sand in these areas.
In addition to reducing the number
of rejected molds, the foundry was able
to reduce additional costs, as the formerly
used stations for applying and
drying the black wash were not required
anymore.
The molding plant can be operated
in combination with two different
types of sand (filling sand and facing
Casting Plant & Technology 1/2015 23