IMPROVING MOLD SETS FOR LARGE-SIZE COMPONENTS
PREPARED FROM AQUEOUS SLIPS.
PART 3. DESIGNS OF MOLD SETS
E. I. Suzdal’tsev,
D. V. Kharitonov,
A. V. Dmitriev,
and T. P. Kamenskaya
Translated from Novye Ogneupory, No. 7, pp. 48 – 52, July, 2006.
Original article submitted January 10, 2006.
An integrated study has been made on searching for new mold set designs and technological solutions to elim
inate the effect of nonuniform buildup of ceramic preforms on the rejection rate. New molding equipment is
proposed equipped with a molding monitoring system and an innovative centering device, which makes it
possible to decrease the rejection rate in molding.
Parts One and Two of the present study considered vari-
ous materials used in the active part of mold sets and possi-
bilities of using various molding methods. The advantages
and disadvantages of these techniques were discussed and
slip casting into porous molds was found to be the optimum
method in terms of cost and technological simplicity. It was
also established that to improve the efficiency of slip casting
for large-size ceramics production, attention should be fo-
cused on searching for new design solutions to eliminate a
nonuniform buildup of large preforms and decrease the gra
dient of physicotechnical properties throughout the height of
At first glance, the simplest technical solution eliminat
ing the above drawback could be a molding set with a gradi
ent of the absorption capacity of its active part. It would ap
pear that a gradient of the absorption capacity of a mold can
be achieved by making the active part of the mold from dif
ferent materials (gypsum, gypsum with a filler, ceramics,
etc.) that have different buildup rates (Fig. 1). However, the
practical implementation of this solution involves a number
of difficulties. First, it is impossible to design a mold set
whose active part had a smooth buildup rate gradient. Sec
ond, due to the significant difference between the CLTEs of
different materials, in drying the active part of the mold is
destroyed in the transition zones between different materials.
Another solution intended to decrease the buildup rate
gradient along the extent of the product is the molding set
whose design is schematically shown in Fig. 2. The main ele-
ment of the proposed mold is the so-called semiactive core,
whose outer surface is coated by a variable-thickness layer of
a moisture-absorbing material. The distribution of the active
layer thickness along the core extent depends on the size and
profile of the particular product . The preform wall
buildup in this mold is carried out from two sides. Due to the
small thickness of the porous layer in the lower part of the
core (up to 1 mm) it has no essential effect on the wall
buildup rate, whereas in the upper part, where the layer
thickness may reach 10 mm, we observed an increased pre
Refractories and Industrial Ceramics Vol. 47, No. 4, 2006
1083-4877/06/4704-0221 © 2006 Springer Science+Business Media, Inc.
Tekhnologiya Research and Production Enterprise, Obninsk,
Kaluga Region, Russia.
Fig. 1. Scheme of a mold set with a porous mold made of materials
with different absorption properties: 1 ) replenishment tanks, 2 )
core, 3 ) porous mold, 4 ) preform, 5 ) casting tank.