Study on parameters on cutting AAC by wires

ss of the surfacemust be smaller than
0.1mm to paint the wall easily. The block dimension also needs high precision so that the wall will
be straight when blocks are superposed. However, in this paper, the roughness of the block surface
will be only researched because the roughness will decide the cost, and the dimension decide the
estheticism of the wall. The block is made by using steel wires to cut big AAC blocks into small
blocks. Influences of working parameters on the steps of the steel wire sawing processes are feed
rate, wire speed and tension. Each parameter will affect surface quality with different effects. Be-
sides, these parameters affect each other, which causes scratches on the AAC surface. Experiments
will bemade tomeasure the height of roughness with the change of wire speed, feed rate and ten-
sion. The best parameters will be found, which helps the AAC manufacturer to obtain the higher
quality.
Key words: Autoclaved Aerated Concrete, steel wire, roughness
INTRODUCTION
The AAC material was made in Sweden in 1924. In
Europe, it has become the most well-known building
materials and is rapidly developed in a lots of coun-
tries in the world. AAC is made from the materials
found easily such as: sand, lime, water, a little rising
agent and cement. After the mixture is mixed and
molded, it is autoclaved in an oven with reasonable
pressure and heat to create unique properties. AAC
possesses the excellent quality of thermal insulation
and acoustic absorption and. AAC also have ability
of pest resistant and fire. AAC is competitively and
environmentally superior to traditional building ma-
terials such as wood, stone, concrete and brick. When
AAC is cast andmixed in structures, a few compound
reactions occur that make AAC light (The AAC den-
sity is 20% of cement one) and warm properties. Alu-
minum powder in compound reacts with water and
calcium hydroxide to produce hydrogen gas. The hy-
drogen gas is created and makes the volume of the
blend rise to 3mm in the surface. When the frothing
procedure has finished, the hydrogen escapes from the
compound and the air supplanted these position.
When the compound forms are removed from the
mould, they are in solid state but rather soft. They will
be cut into either panels or blocks and put in a cham-
ber with heat and pressure during 12 hours. The steel
wires are often used to cut. During hardening pro-
cess under steam pressure, the temperature will ob-
tain 190 Celsius and the team pressure will be from
8 to 12 bars. Quartz sand reacts with calcium hydrox-
ide to produce calcium silicate hydrate. This process
gives AAC high strength and unique properties. Al-
though the processing temperature is about 200o Cel-
sius, AAC blocks are not classified as fired brick but
a lightweight concrete masonry unit. When the auto-
claving process has finished, the ACC block is imme-
diately ready for use on the construction work. De-
pending on processing and ratio of material, its den-
sity can reach to 80% of air in an AAC block. How-
ever, AAC with low density often have low compres-
sion strength. The maximum load of AAC can reach
to 8MPa ~1,160 PSI, it equals 50% of the compressive
strength of concrete.
Asmentioned above, the ACCwill be cut by steel wire
with diameter of 0.5 to 0.8 millimeter. When cutting,
parameters consisting of wire speed, feed rate and ten-
Cite this article : Luu T T. Study on parameters on cutting AAC bywires. Sci. Tech. Dev. J. – Engineering
and Technology; 4(1):730-737.
730
Science & Technology Development Journal – Engineering and Technology, 4(1):730-737
sion will be determined to obtain the lowest rough-
ness. Almost kinds of brittlematerials (including con-
crete, rocks and ceramics) and wood can be sawed by
using a steel wire with smooth surface1. The vibration
of wire is mentioned, which the damped frequencies
of the cutting wire will increase when the contact span
is larger2. This problem makes the resonant change
and then the roughness will increase. The pressure on
the block is permanent3. As the speed of the wire in-
creases, the number of cutting diamond grains in a
second increases and the depth of the diamond grains
into granite will decrease. The cutting efficiency will
increase obviously and the cutting force decreases re-
markable. This leads to the low roughness. It is said,
the amplitude of vibration of the wire saw manufac-
turing process needsminimizing across a spectrum of
excitation frequencies to decrease the kerf loss4. The
analysis of frequency spectrum says that it is very ef-
fective to increase the tension of wire for reducing the
vibration amplitude and kerf loss than to change the
speed of the wire. When the tension of wire is in-
creased, the stiffness of the system is also increased,
as result of the reduction of kerf loss. The width of
the cutting zone is always greater in the forward direc-
tion than in the backwarddirection because the longer
wire travel distance associated with the forward direc-
tion5. The cutting zone width (CZW) near the wire
entry region is almost always greater than that the
wire exit for both cycle schemes. The CZW varies in
the feed direction, the forwardmotion direction often
makes the CZW bigger. That means that the cutting
zonewidthwill decrease from the bottom to the top of
the compound. In another reference, the wire cutting
is experimented and the Taguchi method was used to
select the best parameters to get a lowest roughness6.
It is said that the smaller the grain size combined with
a fast wire speed and low feed rate delivered a much
better surface roughness. It is understood when grain
size is lager, the wire speed and the feed rate is faster
and with the slurry, the material removal rate is bet-
ter. When the grain size is smaller, kerf width will be
better. This is because when the grain size is bigger,
diameter in the saw is larger.
In problems of wire cutting, if the cut material is dif-
ferent, the parameters will be different. However,
their characteristics are almost same such as fast speed
wire, increasing feed rate, wire tension, which leads
to a change of roughness. In this paper, the steel wire
will be used to cut AAC. Three parameters must be
determined to find optimal ones. Experiments will be
done with a cutting machine in which the steel wires
were fixed on a steel framemoving forward and back-
ward. When the parameters said above are measured,
the statistical data will be found. Based on them, the
optimal parameters will be shown.
EXPERIMENT EQUIPMENT
In the Figure 1, the structure of the cutting wire
system is shown. This machine consists of a steel
frame canmove forward and backward on linear bear-
ings. These linear bearingsmake themovement of the
frame smooth, which prevents unnecessary vibrations
from affecting the cutting wire. Amotor with gearbox
will make an eccentric shaft rotate. This shaft together
with connecting rod will cause the steel frame move-
ment. This structure is themodel of slider-crank link-
age.
However, if there is one steel frame, this machine will
vibrate strongly. This occurs because the slider-crank
linkage is difficult to balance. To reduce this vibra-
tion, two steel frames are rebuilt so that they will be
symmetric. Because vibration forces produced in pe-
riod of the frame movement decrease, the cut surface
qualify will be better.
The feeder rate will be performed by a hydraulic cylin-
der. The cylinder will make the steel frame go up or
down. The feeder rate will be controlled by a restric-
tor valve. When adjusting the restrictor, the feeder
rate will change. The lifting or lowering velocity of
the steel frame will represent the feeder rate. Thus,
the velocity parameter is equal to the feeder rate one.
The cutting wire is hung on the steel frame. When the
steel frames move, they make the wires move and cut
the block, Figure 2. In order to cut the block, three pa-
rameters must be determined: the tension of the wire,
the speed of the wire, and the lowering velocity. The
tensions of wires are produced by leaf springs. There
are two leaf springs fixed at two ends of wire. One end
of the leaf spring is connected with the steel frame and
the other with the cutting wire. The wire tension can
adjust up or down by a bolt and nut.
Table 1: Manufacturing condition of cutting wire
Parts Material and Dimension
Cutting wire Steel
Diameter of wire 0.5 mm
Tension strength 5 to 20 kgf
Movement distance. 150 mm
Swing frequency 20 to 40 Hz
Lifting and lowering ve-
locity
3 to 20 meter/minute.
Swing frequency 20 Hz.
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Science & Technology Development Journal – Engineering and Technology, 4(1):730-737
Figure 1: Structure of the cutting wire system.
Figure 2: Real structure of the cutting wire system.
The manufacturing conditions of cutting the block is
displayed inTable 1. Three parameters needing to find
optimization consist of tension strength, cutting ve-
locity, feeder rate. To change the tension strength, the
bolts will be adjusted. The tension can change from 5
to 20 kgf. To change the cutting velocity, swing fre-
quency will be adjusted by an inverter which controls
a motor. Last one, the feeder rate is changed by a hy-
draulic restrictor valve that raises or lowers the steel
frame.
EXPERIMENTMETHOD
The AAC block will be produced from mixture of ce-
ment, clay, sand, and hydrogen gas. This mixture is
put in mould during one to two hours. This time, the
blocks become soft and spongy. Then, they are sent
to the cutting machine. The experiment will be made
here. Three parameters will change to find the regres-
sion equation. After cutting, the block is heated to
120 Celsius degrees and become hard after 1 day. The
AAC block is separated into small bricks. The rough-
ness will be measured by Surface Roughness Tester as
shown in Figure 3.
Data of the experiment consists of the inputs: ten-
sion, swing frequency, lowering velocity and output:
Roughness. The values of input will be showed in Ta-
ble 2.
From the experimental data, the diagrams of tension
versus toughness are shown in the Figure 4. The re-
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Science & Technology Development Journal – Engineering and Technology, 4(1):730-737
Table 2: Experimental data
No Tension Swing frequency (Hz) Lowering velocity (m/m) roughness (mm)
1 5 20 5 220
2 5 20 12 300
3 5 20 20 320
4 5 30 5 200
5 5 30 12 410
6 5 30 20 340
7 5 40 5 150
8 5 40 12 330
9 5 40 20 320
10 10 20 5 210
11 10 20 12 280
12 10 20 20 310
13 10 30 5 180
14 10 30 12 420
15 10 30 20 350
16 10 40 5 150
17 10 40 12 360
18 10 40 20 360
19 15 20 5 205
20 15 20 12 270
21 15 20 20 305
22 15 30 5 180
23 15 30 12 345
24 15 30 20 345
25 15 40 5 160
26 15 40 12 345
27 15 40 20 345
sults are same as that of reference1–6. When the ten-
sion is increased, the stiffness of the system is also in-
creased, as a result that the roughness reduces. These
problems are illustrated in Figure 4. However, the ten-
sion is not infinite growth. The growth of tension does
not result in better surface 3. It is only sound in a gap
of tension. The roughness seems not to decrease when
the tension is more than 16 kgf.
The damped frequencies of the system decrease
slightly when the wire speed increases 4. As a result,
the vibration amplitude reduces and the surface will
be smoother. In other words, the roughness will de-
crease. This phenomenon is explained in Figure 5.
When the lowering velocity increase, the surface
seemsmore terrible (Figure 6). This conclusion is said
(4) that the lower wire speed is desirable in reducing
the vibration of the wire. In other words, the increase
of lowering speed make the wire vibrate stronger and
the surface rougher.
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Science & Technology Development Journal – Engineering and Technology, 4(1):730-737
Figure 3: Surface roughness tester
ANALYSIS OF VARIANCE (ANOVA)
AND CORRELATIVE COEFFICIENT OF
CUTTING PARAMETERS
The ANOVA help to find out which cutting parame-
ters influence the result of performance. It is done by
separating the total variability of the relational grades.
This work is done by the total of the squared devia-
tions with the total mean of the relational grade, into
contributions by each the error and cutting process
parameters.
This research was made on an ANOVA of data with
the wire tension, the swing frequency and the lower
velocity. The objective of analyzing the effective of
three group data is each data group will be indepen-
dent or dependent. This analysis was done for a level
of significance of 5%, that means it obtain the con-
fidence of 95%. The Table 3 showed that the data
groups: the wire tension, the swing frequency and the
lower velocity are independent of each other.
In 3 data groups, the wire tension, the swing fre-
quency and the lower velocity, which group plays an
Figure 4: The tension versus roughness with SF:
Swing frequency (Hz), LV: Lowering velocity (m/m).
Figure 5: The Swing Frequency versus Roughness
with T: Tension (kgf ), LV: Lowering velocity (m/m).
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Table 3: ANOVA Single factor
Groups Count Sum Average Variance
Tension 27 270 10 17,3
Frequency 27 810 30 69,2
Velocity 27 333 12,3 39
ANOVA
Source of Variation SS df MS F P-value F crit
Between Groups 6458 2 3229 77,1 0 3,1
Within Groups 3264 78 41,8
Total 9722 80
Figure 6: The lowering velocity versus roughness
with SF: Swing frequency (Hz), T: Tension (kgf )
important role, is very necessary. When operating the
cutting machine, the workers can adjust few parame-
ters instead of all of parameters. All parameters are
only adjusted at the first time of shift. Few important
parameters can be adjusted during operating time.
A correlation coefficient is a numericalmethod of cor-
relation, which meaning a statistical relationship be-
tween two variables. The variables may be two or
three groups of a given data set. It is often called a
sample, or two or three components of a multivariate
random variable with a known distribution. In this
paper, correlation coefficient will help to select im-
portant parameters for frequently adjustment. After
using excel program to calculate the correlation coef-
ficient, the parameter: lower speed, keep as important
relation with the surface roughness.
DISCUSSION AND RESULT
Using the wire for cutting gives a significant method
to manufacture the AAC block. To increase the sur-
face quality, some parameters can be adjusted. Al-
though there are about 10 parameters to influence to
the surface quality, there are only threemain ones: the
feed rate, the wire speed and the tension. The best pa-
rameters are 5, 40, 5 of tension, swing frequency and
lowering velocity respectively. However, the impor-
tant parameter, speed rate, can be used frequently af-
ter others are adjusted by engineers.
CONCLUSION
The paper introduced three important parameters
in the AAC cutting machine: the wire tension, the
swing frequency and the lower velocity in increas-
ing the surface quality. The experiments showed that
the increase of lowering speed make the wire vibrate
stronger and the surface rougher. When the tension
of wire is increased, the stiffness of the system is in-
creased too, as a result that the roughness reduces.
The vibration amplitude reduces and the surface will
be smoother. However, when operating the cutting
machine, the important parameter is the lower veloc-
ity and workers will operate the cutting machine eas-
ier with only one parameter lower velocity.
ACKNOWLEDGEMENTS
This research was supported by Viet Nam National
University Ho Chi Minh City under grant number
c2020-20-09.
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Science & Technology Development Journal – Engineering and Technology, 4(1):730-737
LIST OF ABBREVIATIONS
ANOVA: Analysis Of Variance.
AAC: Autoclaved Aerated Concrete.
COMPETING INTERESTS
The authors guarantee that there is no conflict of in-
terest in the publication of the article “Study on pa-
rameters on cutting AAC by wires”.
CONTRIBUTIONOF THE AUTHORS
Tung T. Luu did works in this paper.
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Tạp chí Phát triển Khoa học và Công nghệ – Engineering and Technology, 4(1):730-737
Open Access Full Text Article Bài Nghiên cứu
Trường Đại học Bách Khoa –
ĐHQG-HCM, Việt Nam
Liên hệ
Lưu Thanh Tùng, Trường Đại học Bách Khoa
– ĐHQG-HCM, Việt Nam
Email: ttluu@hcmut.edu.vn
Lịch sử
 Ngày nhận: 18-11-2020
 Ngày chấp nhận: 16-3-2021
 Ngày đăng: 30-3-2021
DOI : 10.32508/stdjet.v4i1.795
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© ĐHQG Tp.HCM. Đây là bài báo công bố
mở được phát hành theo các điều khoản của
the Creative Commons Attribution 4.0
International license.
Nghiên cứu những thông số cắt gạch bê tông khí chưng áp
Lưu Thanh Tùng*
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TÓM TẮT
Gach bê tông khí chưng áp (AAC) là sản phẩm xây dựng nhẹ, chịu tải, cách nhiệt cao, bền, được sản
xuất với nhiều kích cỡ và độ bền khác nhau. Khối gạch AAC nhẹ khi so với gạch đỏ, khối AAC nhẹ
hơn ba lần. Khối gạch AAC đang phát triển nhanh chóng tại Việt Nam. Khối gạch AAC có nhiều ưu
điểm hơn như đúc sẵn và xây gạch dễ dàng. AAC được sản xuất từ các nguyên liệu phổ biến là vôi,
cát, xi măng và nước, cùng một lượng nhỏ chất tạo khí. Sau khi đó nguyên liệu được trộn và đưa
vào khuôn. Sau đó, khối gạch AAC sẽ được cắt thành gạch block bằng dây thép. Khi cắt khối gạch
ACC, bề mặt gạch block phải nhẵn để không cần trát vữa. Hơn nữa, độ nhám của bề mặt phải nhỏ
hơn 0,1mm để sơn tường dễ dàng. Kích thước khối gạch AAC cũng cần độ chính xác cao để bức
tường sẽ thẳng khi xếp các khối gạch AAC chồng lên nhau. Tuy nhiên, trong bài báo này sẽ chỉ
nghiên cứu độ nhám của bề mặt gạch vì độ nhám sẽ quyết định giá thành. Khối gạch AAC được
tạo ra bằng cách sử dụng dây thép để cắt các khối AAC lớn thành các khối AAC nhỏ. Ảnh hưởng
của các thông số công nghệ đến hiệu suất của quá trình cắt bằng dây thép là tốc độ dây, tốc độ
tiến dao và lực căng. Mỗi thông số sẽ ảnh hưởng đến chất lượng bề mặt với những tác động khác
nhau. Ngoài ra, các thông số này ảnh hưởng lẫn nhau, là nguyên nhân gây ra các vết xước trên bề
mặt khối gạch AAC. Các thí nghiệm sẽ được thực hiện để đo chiều cao của độ nhám với sự thay
đổi của tốc độ dây, tốc độ tiến dao và lực căng. Các thông số tốt nhất sẽ được tìm thấy, giúp sản
xuất AAC có chất lượng cao hơn.
Từ khoá: Gạch bê tông khí chưng áp, dây thép, độ nhấp nhô
Trích dẫn bài báo này: Tùng L T.Nghiên cứu những thông số cắt gạch bê tông khí chưng áp. Sci. Tech.
Dev. J. - Eng. Tech.; 4(1):730-737.
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