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INVESTIGATION OF DEFECTS OCCURRING IN THE CASTING SHOP PROCESS OF CERAMIC SANITARYWARE ON THE FINAL PRODUCT

Authors:
Black Sea Journal of Engineering and Science
doi: 10.34248/bsengineering.1347161
BSJ Eng Sci / Nihal Derin COSKUN et al.
527
This work is licensed (CC BY-NC 4.0) under Creative Commons Attribution 4.0 International License
Open Access Journal
e-ISSN: 2619 8991
INVESTIGATION OF DEFECTS OCCURRING IN THE CASTING
SHOP PROCESS OF CERAMIC SANITARYWARE ON THE FINAL
PRODUCT
Nihal Derin COSKUN1*, Eray CASIN2, Cumhur Eren ISIK3
1Ordu University, Faculty of Fine Arts, Department of Ceramics and Glass, 52200, Ordu, Türkiye
2Genesis Technological Products Industry and Trade. Inc., 19010, Çorum, Türkiye
3Kütahya Dumlupınar University, Faculty of Fine Arts, Department of Handicraft Design and Production, 43020, Kutahya, Türkiye
Abstract: When the export values of ceramic sanitaryware in T are analyzed, it is seen that the data for the year 2022 of ~660
million dollars continues to increase. In the sector, which reaches an annual average increase of 100 million dollars, the amount of
production as well as the design demands change and shape the market. The most important difficulty factors in design are due to the
fact that the products in the sector have large sizes, complex shapes and the most human-made production stages. When these factors
are compared with other ceramic sectors, it is revealed that although industrialization has increased in the production of ceramic
sanitaryware, the lack of production amount and the excess of faults are among the biggest problems. Glaze faults are the leading faults
observed in the final product, and since this problem is not recyclable, it harms the ceramic sanitaryware industry in terms of cost. In
this study, the glaze faults reflected in the final glazed products originating from the casting shop stage, which attracts attention in this
field due to its large size and whiteness and there is not much data for the vitreous ware industry in the literature, have been studied.
In the study, which was carried out with the aim of detecting and eliminating some faults in industrial production and creating data for
the literature, faults arising from mechanical evenings used in classical and pressure casting benches and material residues used in
retouching processes were determined. These faults were produced on the basis of the laboratory and the characterization of the
glazed faulty products was made. It is concluded that production losses can be reduced by eliminating these problems, consequently
increasing quality and productivity.
Keywords: Sanitaryware, Casting department, Glazing, Ceramic manufacturing defects
*Corresponding author: 
E mail: nihalderincoskun@odu.edu.tr (N. D. COSKUN)
Nihal Derin COSKUN
https://orcid.org/0000-0002-3024-9443
Received: August 21, 2023
Accepted: September 28, 2023
Published: October 15, 2023
Eray CASIN
https://orcid.org/0000-0003-3698-2248
Cumhur Eren ISIK
https://orcid.org/0000-0002-1129-2497
Cite as: Coskun ND, Casin E, Isik CE. 2023. Investigation of defects occurring in the casting shop process of ceramic sanitaryware o n the final product. BSJ
Eng Sci, 6(4): 527-534.
1. Introduction
Ceramics is an area that consists mainly of shaping and
firing kaolin, quartz, feldspar and clay raw materials and
provides functional use in the industrial sense.
Sanitaryware (also known as vitrified ceramics) serves
the industry as an important industrial production
branch of ceramics, which has an important place in the
ceramic industry in terms of providing hygiene and ease
of life to people. Washbasins, toilet bowls, urinals,
shower trays, etc. are the articles manufactured in this
sector. The products are sintered at ~1200-
are in the scale of products that are difficult to
manufacture, as they are large-sized, durable and low-
water absorption products with a glassy glaze layer
covering them. Although these products can be colored,
they are preferably produced in white color as it is
suitable for customer demand (Canduran ve Ural, 2019;
Mete, 2020; Taykurt Daday, 2012).
As seen in Figure 1, different textures and impurities
provide artistic effects in artistic ceramic production.
However, in vitrified products, which are an industrial
production branch, these images visually distort the
effect as seen in Figure 2. Since they are relatively large
in size, these products go to waste which has a negative
impact on production in terms of raw materials, labor,
energy and time. These faults can also be seen in a
porcelain plate or ceramic tile product, but the biggest
loss is more visible in the sanitaryware industry due to
its larger size (Fortuna and Fortuna, 2017; Fraser, 2005).
Many studies have been done and are being carried out
on ceramic defects in areas such as tableware and the tile
sector, which require more patterns and designs. Efforts
to eliminate these faults and possible causes of defects
are determined, and some of the main faults in the
literature are seen in Figure 3.
Research Article
Volume 6 - Issue 4: 527-534 / October 2023
Black Sea Journal of Engineering and Science
BSJ Eng Sci / Nihal Derin COSKUN et al.
528
Figure 1. Some glaze defects used as artistic effects in artistic ceramic products ;
.
Figure 2. Manufacturing defects on some vitrified products.
Figure 3. Some ceramic glaze defects ( Hopper, 2023).
Casting shop related defects in vitreous ware are
generally in the literature; voids, points, lines, cracking,
explosions due to plaster residues, deformations caused
by uneven drying and air bubbles during filling. However,
there are also faults that appear in the final product.
These faults can be caused by various components and, in
a sense, by human faults (Fortuna and Fortuna, 2017;

In this study, the effects of defects occurring from the
casting shop may occur in the final product stage besides
the pre-sintering stage, and especially the effects of
defects originating material based issues and their effects
on the microstructure were investigated.
2. Materials and Method
Five of the materials utilized in the slip casting that cause
the most faults were selected and these materials were
applied on the specimen plates. Although the visuals of
the faults on the plates in the experimental studies seem
to be major, these defects are considered as minor in
production. In fact, due to the plastic or polymeric
materials used, it may move away from the body at ~250
     
air, crater or pinhole defects. Semi-finished products and
raw materials used in factory conditions and production
were supplied from Ece Bathroom production facility.
Microstructure studies (SEM) of the study were
performed by scanning electron microscope and
chemical composition analysis (EDX). SEM/EDX images
were measured with Zeiss Supra 50VP Brand device.
2.1. Casting Shop based Faults
2.1.1. Defects due to green scotch
Green scotch is a material that is generally used for
retouching the surfaces of semi-finished products
containing 18% moisture from casting. It is especially
used for rounding corners. It can also be used in semi-
finished products after drying. Many apparatuses are
used during the retouching in the casting shop, but since
the green scotch comes into contact with the product
with plenty of water, they can be buried in the product
from time to time and cannot be noticed in the process
(Figure 4).
Black Sea Journal of Engineering and Science
BSJ Eng Sci / Nihal Derin COSKUN et al.
529
Figure 4. Green scotch (Right) and defects due to green
scotch (Left).
2.1.2. Die casting machine materials
Pressure casting benches are different from conventional
casting benches, they are more mechanical and have
many moving and rotating parts. Machine elements such
as belts or bearings are used in the rotational movements
of these machine parts or the movements of the moving
parts. Lubrication processes are also carried out to
prevent the wear of these elements. The presence of
water in the working environment causes these oils to
clump and stick to the products in cases where cleaning
processes are not carried out in a controlled manner. In
addition, the abrasions that may occur due to the friction
of some parts against each other and the resulting metal
slags also cause the formation of metallic stains (Figure
5).
Figure 5. Die casting machine slag materials (Right) and
defects caused by them (Left).
Many sanitaryware products such as sinks and toilet
bowls are produced on the pressure casting benches as
seen in Figure 6. However, while the molds are being
opened, especially in products such as large-sized toilet
bowls or similar shower trays, metallic parts that are
poured from the upper part of the counter due to friction
cannot be detected because they are taken into the
system by robots without human touch. These types of
defects also appear as stain faults at the exit of the kiln.
Figure 6. Vitrified die casting machine from Ece Banyo.
2.1.3. Strip tape abrasive based defects
Strip tape abrasive is a hard, metallic abrasive type used
in ceramic sanitaryware at the stage of semi-finished
product control. This abrasive, which is generally
preferred in the retouching processes carried out under
the control of the products after drying, is used to ensure
the rapid flow of semi-finished products. The reason for
this is that it has a high ability to retouch, since it is a
hard abrasive. After using this abrasive in the semi-
finished product control process, the surface should be
wiped with a damp cloth again and the touch-up marks
on the surface should be closed. Since it is a metal-based
material, it causes staining in case of any wear or
breakage (Figure 7).
Figure 7. Strip tape abrasive (Left) and defects (Right)
due to this abrasion.
2.1.4. Faults from abrasive materials
Box shaped abrasives are a different type of abrasive
used in casting shop and used to perform surface
treatments of products. It is a material that can be
touched up without damaging the surfaces, since the
eroding part is soft, box-shaped and has a sponge in the
middle. In some cases, stains can be seen if this abrasive
Black Sea Journal of Engineering and Science
BSJ Eng Sci / Nihal Derin COSKUN et al.
530
(silicon carbide) wears off and the wearing parts adhere
to the surfaces. In addition, abrasive particles that
dissolve in the retouching waters in the casting shop and
adhere to the surface with slip particles also cause
staining (Figure 8).
Figure 8. Box Abrasive (Left) and Related Defects
(Right).
2.1.5. White abrasive based defects
This type of abrasives is generally used in the semi-
finished product control phase. White color is the chief
reason for this abrasive to be utilized in the retouching
process of the semi-finished product, because the upper
area of the product is alumina-based. This type of
abrasive is more preferred because black spots are
observed in silicon alumina based abrasives. However, it
is observed that this material also causes defects (Figure
9).
Figure 9. White Abrasive (Left) and its related defects
(Right).
3. Results and Discussion
3.1. SEM /EDX Analysis
3.1.1. SEM/EDX analysis of green scotch based defects
The green scotch-based defects seen in Figure 9 cause
inclusions in the structure since the material is polymer-
based. In the samples studied in a major scale, the
material appears as a mound because it does not
completely melt in the glaze. However, it is not
completely combined in the glassy phase, and it shows
itself as a separate formation from the structure, as seen
the figures (Figure 10).
Since the green scotch is a polymeric material, it does not
leave any residue after firing. The earlier melting
temperature of the material, which is embedded in the
glaze (i.e., if parts remain within the body), causes defect
on the glaze surface.
Figure 10. Some SEM Analysis of Green Scotch Based
Defects A, B, C (Table 1 displays EDX analysis of the
defects).
Since the green scotch is a polymeric material, it does not
leave any residue after firing. The earlier melting
temperature of the material, which is embedded in the
glaze (i.e., if parts remain within the body), causes defect
on the glaze surface.
Table 1. EDX analysis of green scotch based defects in
Figure 10.
MgO
Al2O3
CaO
ZnO
SiO2
Na2O
K2O
ZrO2
Total
0
30.89
6.67
0
55.43
7.01
0
0
100
0
24.94
6.87
0
64.46
2.77
0.96
0
100
1.16
9.62
8.14
1.72
57.9
3.21
0.75
17.5
100
As seen in Table 1, in the analysis of the points where the
Al2O3 ratio higher, ZrO2 ratio is not observed in the
structure, indicating the green scotch is causing defects
in the regions. The defect of the natural opaque glaze
structure is evidenced by the zircon ratio.
Black Sea Journal of Engineering and Science
BSJ Eng Sci / Nihal Derin COSKUN et al.
531
3.1.2. SEM/EDX analysis of defects due to die casting
machine materials
Since there are iron particles in the machine oil, and the
viscosity of the oil increases and becomes semi-solid due
to friction, iron defects are encountered on the product
surface. Also, assuming that the oil lowers the surface
tension, it is likely to cause glaze collection in cases
where the body absorbs the oil (Figure 11).
Figure 11. Some SEM Analysis of Defects Due to Die
Casting Machine Materials (A, B, C, D) (Table 2 displays
EDX analysis of the defects).
The high Fe2O3 ratio in the point analyzes in Table 2
shows that the parts poured over the machine are iron-
containing. However, although there is a structure that
creates a depression in the iron structure, it is seen that
the other impurities that come with the iron do not melt
completely, allowing the structure to remain rigid.
Table 2. EDX analysis of defects in figure 11 due to die
casting machine materials
Ex.
No
MgO
Al2O3
CaO
Fe2O3
ZnO
SiO2
Na2O
K2O
ZrO2
MnO
Total
A
0
35.22
0
3.3
0
58.1
2.76
0
0
0.61
99.99
B
0
0
0
100
0
0
0
0
0
0
100
C
4.55
17.66
4.1
24.47
4.18
43.27
0
0.85
0
0.92
100
D
1.14
9.27
6.21
0
1.39
58.96
2.84
0
20.2
0
100
3.1.3. SEM/EDX analysis of tape abrasive based
defects
The tape abrasive is made of hard metallic materials.
When seen under the glaze, it creates iron stains on the
glaze surface. It has been observed that since it is placed
as a whole piece in the figure, it does not spoil the glaze
surface and behaves like a glaze in EDX analyses (Figure.
12).
Due to the application of the defect as a major part in the
experimental studies, the abrasive remained under the
glaze surface without melting and it was observed that
there were glaze surfaces in the SEM/EDX analyzes. It
has been determined that the EDX analysis, which
provides a homogeneous image of the structure, also
supports this idea (Table 3).
Table 3. EDX analysis of tape abrasive-based defects in
figure 12
Ex.
No
MgO
Al2O3
CaO
ZnO
SiO2
Na2O
K2O
ZrO2
Total
A
1.28
11.47
7.5
0.72
70.77
4.66
0.51
3.09
100
B
0
4.24
5.66
0
43.97
2.2
0
43.93
100
C
1.05
7.9
8
0
56.22
3.77
0
23.07
100.01
Black Sea Journal of Engineering and Science
BSJ Eng Sci / Nihal Derin COSKUN et al.
532
Figure 12. Some SEM/EDX Analysis of Tape Abrasive
Based Defects (A, B, C) (Table 3 displays EDX analysis of
the defects).
3.1.4. SEM/EDX analysis of box abrasive based
defects
Box abrasives are applied on semi-wet products in the
casting process. Especially the inner chambers of the
toilet bowls and the fluffy parts on the outer surfaces are
cleaned with these abrasives. For this reason, it is desired
that this product should be hard. However, in the SEM
images, it is seen that the SiC particles cause
crystallization in the structure and are clustered locally
(Figure 13).
As seen in Table 4, CO2 formation was found that was not
observed in other EDX analyzes. Another oxide seen here
is SiO2, proving that the material is SiC. In the results
obtained from the faulty areas, it was determined that
the glaze deteriorated on the surface and the ZrO2 ratio
was not found because the SiC material remained
unmelted (Hasanuzzaman et al., 2022).
Figure 13. Some SEM/EDX Analysis of Box Abrasive
Based Defects (A, B, C, D, E, F) (Table 4 displays EDX
analysis of the defects).
Table 4. EDX analysis of box abrasive based defects in
figure 13
Ex.
No
MgO
Al2O3
CaO
ZnO
SiO2
Na2O
K2O
ZrO2
CO2
Total
A
0
20.16
0
0
79.84
0
0
0
0
100
B
0
1.4
0
0
98.6
0
0
0
0
100
C
0
33.11
0
0
66.89
0
0
0
0
100
D
1.05
3.37
2
0
16.97
0
0
0
76.61
100
E
0
2.65
1.11
0
14.22
0
0
0
82.02
100
F
1.09
9.7
6.68
1.71
66.03
2.97
0.38
11.43
0
99.99
3.1.5. SEM/EDX analysis of white abrasive based
defects
Since white abrasives are based on alumina silicate, it
causes deterioration on the surface. The black spots seen
on it are caused by the falling of the sponge pieces caused
by friction and burning on the surface. The appearance of
abrasive pieces on the glaze surface ensures that there
are regions in the glaze structure as in the 2nd figure in
Figure 14. As examined in the SEM images, it is seen that
the alumina silicate layers deposited on the surface tend
to mullite structures and begin to turn into a rod-like
form. This causes refractory structures within the glaze,
thereby distorting the appearance of the glaze (Figure
14).
Black Sea Journal of Engineering and Science
BSJ Eng Sci / Nihal Derin COSKUN et al.
533
Figure 14. Some SEM/EDX Analysis of White Abrasive
Based Defects (A, B, C, D, E, F) (Table 5 displays EDX
analysis of the defects).
It also shows itself in EDX analyzes with the decrease in
zircon ratios in which the glaze structure is deteriorated.
The increased alumina ratio coincides with the EDX
values taken from the samples (Table 5).
Table 5. EDX analysis of white abrasive-based defects in
figure 14
Ex. No
MgO
Al2O3
CaO
SiO2
Na2O
K2O
ZrO2
Total
A
0
25.77
0
74.23
0
0
0
100
B
0
16.14
0
83.86
0
0
0
100
C
0
32.55
0
67.45
0
0
0
100
D
0
23.25
0
76.75
0
0
0
100
E
0
32.47
0
67.53
0
0
0
100
F
1.46
9.78
5.56
63
5.95
0.29
13.94
99.98
4. Conclusion
The casting is one of the first stages of production, and
the defects that occur here are sought in the next process
rather than the final product. However, in the study, it is
revealed that these defects can also affect the final
product and the use of the materials utilized properly
and by changing will affect the quality of the final
product. In this respect, it can be said that some types of
defects, which are generally seen as workmanship
defects, may also be caused by material deformations and
it is important to detect this by the production foremen.
It has been observed that material-related defects may be
polymer-based, as well as from hard materials with
refractory properties such as metallic or SiC. When these
defects are characterized, they can differentiate from the
normal opaque vitrified glaze structure and create
crystallized or deformational images. Sometimes the
change in the ratio of alumina, sometimes silica, and in
some cases, zircon, guides us to determine the damages
caused by these materials to the structure.
Even if the ratio of the materials used is relatively low, it
has been observed that it affects the crystallization in the
glaze structure and causes staining and deterioration on
the final product. SEM/EDX analyzes play an active role
in determining the extent of damage to the product at the
final stage.
Thus, it is concluded that production losses can be
minimized by eliminating these problems, consequently
increasing quality and productivity.
Author Contributions
The percentage of the author(s) contributions is
presented below. All authors reviewed and approved the
final version of the manuscript.
N.D.C.
E.C.
C.E.I.
C
50
25
25
D
50
25
25
S
50
25
25
DCP
50
25
25
DAI
50
25
25
L
50
25
25
W
50
25
25
CR
50
25
25
SR
50
25
25
PM
50
25
25
FA
50
25
25
C=Concept, D= design, S= supervision, DCP= data collection
and/or processing, DAI= data analysis and/or interpretation, L=
literature search, W= writing, CR= critical review, SR=
submission and revision, PM= project management, FA= funding
acquisition.
Conflict of Interest
The authors declared that there is no conflict of interest.
Ethical Consideration
Ethics committee approval was not required for this
study because of there was no study on animals or
humans. The authors confirm that the ethical policies of
the journal, as noted on the journal's author guidelines
page, have been adhered to.
Acknowledgements
We would like to thank the Ceramic Research Center
(SAM), for assisting the characterizations and also Ece
Banyo Inc. for providing factories facilities.
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BSJ Eng Sci / Nihal Derin COSKUN et al.
534
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Article
Full-text available
Pin‐holing is one of the major glazing defects that the tableware ceramic industry is experiencing. It is evident from this research work that the pin‐holing defect can be prevented or at least reduced by optimizing composition and sintering profile, which in turn yields pin‐hole‐free tableware ceramics. DSC/TGA and dilatometer are found to be effective to understand the thermal behavior of specific ceramic tableware bodies and glaze. Dilatometry was employed to investigate the densification behavior and it was found that densification of the ceramic body reached completion by 1300°C. The final optimum firing temperature and soaking time, which are believed to influence the microstructure and mechanical properties of the ceramicware, were found to be 1300°C and 90 min, respectively. The microstructural change of the ceramic body and glaze sintered at different temperatures and times is observed under FESEM. It was found that the existence of pin‐holing defect largely depends on the feldspar and quartz content in glaze raw material as well as the applied firing profile, and the result was found satisfactory when the ratio (quartz/feldspar) was ∼2. This article is protected by copyright. All rights reserved
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