F. RADKOVSKÝ, V. MERTA: USE OF NUMERICAL SIMULATION IN THE PRODUCTION ...
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USE OF NUMERICAL SIMULATION IN THE PRODUCTION OF
POROUS-METAL CASTINGS
UPORABA NUMERI^NE SIMULACIJE V PROIZVODNJI
POROZNIH KOVINSKIH ULITKOV
Filip Radkovský
*
, Václav Merta
V[B– Technical University of Ostrava, 17. listopadu 2172/15, Ostrava-Poruba, Czech Republic
Prejem rokopisa – received: 2019-07-10; sprejem za objavo – accepted for publication: 2019-11-08
doi:10.17222/mit.2019.145
The article describes the design and optimization of the foundry production of porous metal. The formation of porous metal by
infiltrating liquid metal into the mould cavity appears to be the fastest and most economical way. However, it is not possible to
do it without proper production parameters. For this reason, a 3D model of a particular casting is first created in the Rhinoceros
4.0 software and then the entire production process is designed and optimized using the numerical simulation in the
MAGMASOFT® 5.4 software. To create cavities in the casting, the use of sand cores is considered and the used unit bentonite
mixture (UBM) becomes the mould material. With the simulations of pouring and solidification of the casting, the right
conditions for the real production can be defined precisely; the time and financial costs connected with the production of
non-conforming pieces can be saved. Thus, the aim is to ensure the production of sound castings that will find their use in the
field of energy, specifically as heat exchangers.
Keywords: porous metal, simulation software, casting, heat exchanger
V ~lanku avtorji opisujejo dizajn in optimizacijo ulivanja poroznih kovinskih ulitkov. Ugotavljajo, da je formiranje porozne
kovine s postopkom infiltracije raztaljene kovine v votlino livarskega modela najhitrej{i in najbolj ekonomi~en na~in. Toda tudi
v tem primeru tega postopka ni mo`no izvajati brez ustreznih proizvodnih parametrov. Zato so avtorji najprej kreirali 3D model
izbranega ulitka s programsko opremo Rhinoceros 4.0 in nato s programom MAGMASOFT® 5.4 izvedli numeri~no simulacijo
dizajna in optimizacije celotnega proizvodnega procesa. Za izdelavo livarskega modela so uporabili pe{~ena jedra in betonitno
me{anico (UBM). S simulacijo polnjenja modela z raztaljeno kovino in strjevanja ulitka pri optimalnih pogojih so tako v realni
proizvodnji lahko natan~no dolo~ili ~as in stro{ke, ter s tem prihranke, pri izdelavi ulitkov razli~nih zahtevnih oblik. Avtorji so
tako omogo~ili proizvodnjo kvalitetnih ulitkov, uporabnih na energetskem podro~ju, predvsem za izmenjevalnike toplote.
Klju~ne besede: porozna kovina, programska oprema za simulacijo, litje, toplotni izmenjevalnik
1 INTRODUCTION
A porous metal has intentionally created cavities/
pores in its structure. According to the arrangement of
internal cavities, such materials can be divided into
regular and irregular ones. The internal structure of
porous metals differs depending on the technology used.
A porous metal can be produced in various ways, but the
production is economically demanding; therefore, it is
good to have a production that uses casting technologies
where the lowest costs are expected. As a result, we can
combine the technologies of forming cavities with the
use of sand cores. Depending on the size, openness and
amount of pores, different behaviours are observed in the
field of thermal conductivity. Open pores in a material
increase its thermal conductivity. This can be used for
the design of heat exchangers. The principle is to let a
fluid or gas flow through the open pores of a material,
which will cool down or heat up the porous metal. To
increase the economy of the casting production of heat
exchangers, it is suitable to use the MAGMASOFT® 5.4
– Autonomous Engineering simulation program that is a
very mature tool for the simulation of all the casting
operations from the beginning of pouring to the end of
the cooling process. By correctly setting the simulation
program and boundary conditions, and establishing the
appropriate goals, critical points of the casting can be
found in advance and unnecessary elements of the gating
system that burden the foundry with additional pro-
cessing costs, can be removed.
1–3
2 EXPERIMENTAL PART
Several variants of the heat exchanger in the environ-
ment of the ANSYS CFX simulation program was first
analysed. Based on the calculations of the heat-transfer
simulations, the geometry with ball cores seemed to be
more efficient. A model of a casting and cores was first
created as a drawing and then it was modelled with the
Rhinoceros 4.0 program (Figures 1 and 2) and inserted
into the MAGMASOFT® 5.4 program. After the pro-
duction, the sand cores were put in pairs next to each
other and provided with prints. The material of the
mould used for casting the heat exchanger consisted of
the unit bentonite mixture (UBM). The casting weight
Materiali in tehnologije / Materials and technology 54 (2020) 2, 259–261 259
UDK 67.017:004.942:676.017.62:678.067 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 54(2)259(2020)
*Corresponding author's e-mail:
filip.radkovsky@vsb.cz (Filip Radkovský)

was 4.72 kg and the volume was 1784.28 cm
3
. The used
material was the AlSi10Mg alloy.
4,5
The next step was the creation of several different
variants of the gating system and their comparison.
Subsequently, the suitable candidate for the design-of-
experiments (DoE) analysis was chosen. The porosity of
the casting, the optimum casting temperature of the
metal, the subsequent metal temperature in the casting
before the material solidification, the flow rate of the
metal in ingates and in the casting, the microporosity, the
ability of feeding the used risers, the size and shape of
ingates and the casting time were the monitored para-
meters.
6
3 RESULTS
From the initial simulations that lasted for nearly
120 h, the variant from Figure 3 was chosen as the
suitable candidate for the DoE analysis because it
allowed low filling rates. Optimization was created based
on the variables that were included in the geometry,
namely the ingate width, the angle of the end over-
hanging from the vertical wall up to a 30° incline, the
F. RADKOVSKÝ, V. MERTA: USE OF NUMERICAL SIMULATION IN THE PRODUCTION ...
260 Materiali in tehnologije / Materials and technology 54 (2020) 2, 259–261
Figure 3: Filling rates
Figure 4: Filtered results of the DoE analysis
Figure 2: 3D model of a casting with cores
Figure 1: 3D model of a sand core

riser diameter that was set to the values of the diameter
of the bottom side of (40, 60 and 80) mm and the casting
temperature. Altogether 144 pieces of the variables were
examined. The calculation time of the DoE analysis
subsequently reached 192 h. Of course, the calculation
time could be shortened significantly using a more
powerful station (PC). The overall results of the analysis
were recorded in a chart and filtered results of two
suitable designs are shown in Figure 4. In the top part of
the chart, the criteria according to which the achieved
results were filtered out are described.
The following criteria were used when choosing
suitable candidates: reduction of porosity, minimum
temperature in the casting, minimum temperature of the
metal, lower rate in ingates, lower rate in the casting,
reduction of microporosity, higher feeding ability of the
riser, and usage of liquid metal. A longer filling time was
chosen to comply with the lower rates in ingates. The
riser dimension was changed in terms of its diameter, not
height, due to testing the variants with a sufficient
feeding ability. At the same time, it is evident from
Figure 4 that the candidates satisfying the specified
values are versions 75 and 134.
4 DISCUSSION
Versions 75 and 134 were subsequently added for
comparison. Filling rates of up to 0.5 m/s, which is an
acceptable border, were recorded for the casting. There
was no damage of the cores and the filling was fast
enough. Version 134 on the figure right shows lower
rates than the more turbulent version 75 on the left.
When choosing between versions 75 and 134, it was
decided in favour of version 134. Although version 75
showed a better thermal node and a smaller drop in the
temperature, the riser was uneconomical. Further, ver-
sion 134 showed a more continuous filling of the entire
cavity. With regard to the drop in the temperature of the
134 design, two additional simulations were made, in
which the existing casting temperature compared to the
newly modified one was evaluated. The initial casting
temperature was 745 °C and there were too many tem-
perature drops in narrow intercore areas. The tempera-
ture of the newly simulated sample was set to 755 °C.
Microporosity was also studied in both of the above-
mentioned simulations. The results were positive,
including a very low value of only4%o ft h etotal
volume, spread across the casting body.
5 CONCLUSIONS
The variant with serial number 134, which was simu-
lated at a casting temperature of 745 °C, was selected as
the winning design of the casting. Then the casting
temperature was changed to 755 °C and the variant was
analysed again and compared with the previous state. As
expected, the increased casting temperature had a
positive influence on the fluidity in the intercore areas.
Therefore, the casting temperature of 755 °C was
determined as the minimum temperature for a successful
casting of the tested sample of the heat exchanger. The
riser size was sufficient for eliminating the thermal node
and compensating for the material loss. At the same
time, the gating system allowed faster casting than the
simulation, lasting 11 s. Common conditions used in a
foundry when the casting rate is not strictly observed
were taken into consideration and, therefore, the simu-
lation was calculated with a reserve. The acceleration of
the casting time without a negative influence on the
increase in the flow rate of the metal in the mould cavity
can be up to 15 %.
Acknowledgement
This article was created within project TA02011333,
TH02020668 with the financial support of the Czech
Technology Agency and programs SP2019/43,
SP2019/148, SP2020/39 and SP2020/64.
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/2018_pm_en_magmasoft_rel_5_4.pdf
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