The machined surface of magnesium AZ31 after rotary turning at air cooling condition
G Akhyar 1*, B Purnomo 1, A Hamni 1, S Harun 1, Y Burhanuddin1 Department of Mechanical Engineering, Faculty of Engineering, University of Lampung. Jln. Prof.Sumantri Brojonegoro No.1 Gedung H FT Lt.2 Bandar Lampung Email: gusri.akhyar@eng.unila.ac.id Abstract. Magnesium is a lightweight metal that is widely used as an alternative to iron and steel. Magnesium has been applied in the automotive industry to reduce the weight of a component, but the machining process has the disadvantage that magnesium is highly flammable because it has a low flash point. High temperature can cause the cutting tool wear and contributes to the quality of the surface roughness. The purpose of this study is to obtain the value of surface roughness and implement methods of rotary cutting tool and air cooling output vortex tube cooler to minimize the surface roughness values. Machining parameters that is turning using rotary cutting tool at speed the workpiece of (Vw) 50, 120, 160 m/min, cutting speed of rotary tool of (Vt) 25, 50, 75 m/min, feed rate of (f) 0.1, 0.15, 0.2 mm/rev, and depth of cut of 0.3 mm. Type of tool used is a carbide tool diameter of 16 mm and air cooling pressure of 6 bar. The results show the average value of the lowest surface roughness on the speed the workpiece of 80 m/min, cutting speed of rotary tool of 50 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm. While the average value of the highest surface roughness on the speed the workpiece of 160 m/min, cutting speed of rotary tool of 50 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm. The influence of machining parameters concluded the higher the speed of the workpiece the surface roughness value higher. Otherwise the higher cutting speed of rotary tool then the lower the surface roughness value. The observation on the surface of the rotary tool, it was found that no uniform tool wear which causes non-uniform surface roughness. The use of rotary cutting tool contributing to lower surface roughness values generated. 1. Introduction Magnesium is a lightweight metal and has characteristics similar to aluminum. Magnesium can be
used as an alternative to iron and steel
because
magnesium
is abundant elements and elements that make up the eighth most
2 % of the earth's crust,
and
is the
third
most
element dissolved
in
seawater [1]. On development, magnesium or its alloys
has been
widely
applied in the automotive industry
among others
to
lose
weight
because
of a component
is a metal that is light [2]. Magnesium machining process is known to have excellent cutting characteristics because it has a low specific cutting force, furious chips are short, relatively low tool wear, high surface quality and can be cut at cutting speeds and feeds are high [3]. Although magnesium has many advantages, but
has the disadvantage that magnesium is highly flammable because it has a low flash point.
At such a low flash point will be burning furiously, where the cutting temperature exceeds the melting point of the material, namely (400° C - 600° C)
[4]. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1
In addressing these issues, numerous studies have been conducted to find
an effective method to reduce the
cutting
temperature.
As stated by previous researchers that a high cutting temperatures will produce a high surface roughness values [5]. Because the machining process with high temperature will cause occurrence of wear on the cutting tool so that it can degrade the quality of the workpiece surface roughness [6]. In the machining process, generally the method that is widely used
to lower the temperature of cutting is to use
liquid. But in its development began to minimized use this liquid because it is very dangerous for health and the environment [3]. In the study conducted by Doni [7] which aims to analyze the surface roughness value by lowering
the temperature of the cutting.
The chosen method
is to use a
rotating
cutting tool
on a lathe machining processes without coolant and use a rotary tool tilt angle of 0° with respect to the workpiece. Rotary tool method used successfully obtain minimum surface roughness value of 0.62 μm and a maximum surface roughness values of 2.86 μm. In his research, Doni [7] recommends using low feed rate , because the higher of feed rate will generate greater roughness values. Research on machining magnesium is also done by Andriyansyah [8] which aims to determine
the effect of cutting parameters on surface roughness
values of magnesium
using
air cooling
of
vortex tube cooler with a temperature of 15° C. Machining process used is a milling machining. Research
results show that the
value
of the
minimum
surface roughness of
0.35 μm and maximum roughness value of 1.50 μm. of the research that has been described above concludes
that the value of
the
surface roughness
of magnesium
in
addition influenced by
cutting parameters,
including
feed rate and
the
cutting speed,
also influenced by
the
temperature
of
the cutting. Therefore in this study will be analyzed on a surface roughness values lathe machining process using a rotary cutting tool with a tilt angle of 10 °. In a previous study of this corner enabled to reduce power by 30% of the total power use and reduce the amount of cutting force [9] [10]. The cutting process will be given air cooling output of vortex tube cooler constant. By using cold air is expected to reduce the temperature of the cutting so as
to reduce the
rate of
tool wear and improve tool life
[11] [12]. So this method is expected to produce a better roughness values and can be used as a substitute for innovation in the machining process fluid.
The purpose of this study is to obtain the value of surface roughness and implement methods of cutting tool
rotary tool
and air cooling output
of
vortex tube cooler to minimize the surface roughness values.
2. Research Methodology Laboratory of Manufacturing, Mechanical Engineering, Lampung University. Materials used in the study are magnesium alloy AZ31 (Al of 3% and Zinc of 1%). Here is an AZ31 magnesium physical table property. Table 1. Physical properties of magnesium AZ31 Density [kg/mm3]
Young’s Modulus [kN/mm2] Possion’s ratio Melting temperature [K] Thermal
Conductivity
[w/(mK)]
Heat specific capacity [J/(kgK)] Heat coefficient [K-1] 1,77 x 10-6 45,000 0.35 891 77 + 0.096T 1000 + 0.666T 2.48 x 10-5 The machining is done on conventional lathes brands PINACHO type S-90/200. By using a rotary cutting tool system as shown in Figure 1. The material
of tool used is a carbide, diameter of 16 mm and
the
air cooling pressure of 6 bar.
Here are
the
figure and specifications of the tool cutting system spins and vortex tube : Figure 1. Rotary cutting tool system Table 2. Specifications of rotary tool Merk Tool type Tool rotation speed Speed direction Diameter of insert AXUM590-A Insert-Propeller 0-2000 rpm CW/CCW 16 mm Figure 2. Vortex tube used to produce air cooling.
Machining parameters that is turning using rotary cutting tool at speed the workpiece of (Vw),
cutting speed of rotary tool of
(Vt),
feed rate
(f), depth
of
cut (d).
Can be seen in Table 3. Table 3.
Cutting parameters
selected
in turning process. Speed
of workpiece Feed rate
Vw, m/min f, mm/
ref
Depth of cut
d,
mm
Speed of
rotary
Temperatur tool, Vt e m/menit 80 120 160 0,10 0,15 0,20 0,3 25 50 75 0 °C. 6 Bar Data collection roughness on every parameter done four times. This is done to get the maximum results. Measurement values using a surface roughness tester with an accuracy of 0.01 μm and surface profile of picture a using USB camera with a magnification of 600 x. 3. Results and Discussions In Experimental trials of AZ31 magnesium alloys using conventional turning and rotary cutting tool system with air cooling. To determine the value of the surface roughness material magnesium alloy AZ31 has been carried out with a variety of
machining parameters that is turning using rotary cutting tool at speed the workpiece of (Vw) 50, 120, 160 m/min, cutting speed of rotary tool of (Vt) 25, 50, 75 m/min, feed rate of (f) 0.1, 0.15, 0.2 mm/rev, and depth of cut of 0.3 mm.
Here are the data obtained from the machining process with a variety of conditions, produces a variety of data
as shown in Table 4-
7:
Table 4.
Measurement data
value of
roughness on speed
the
workpiece of 120 m/min,
depth of cut of 0.
3
mm, and cutting speed of
rotary tool of 25 m/min. No Speed of workpiece (Vw)
(m/min) Feed rate (f) (mm/rev) Depth of cut (d) (mm)
Speed of rotary
tool
(Vt) Surface roughness (µm) (m/min) 1 Ra 2 Ra 3 Ra Average (µm) Time (t) (Minute) 1 2 3 4 1 2 3 4 120 0.1 120 0.2 0.3 25 0.3 25 1,22 1,32 1,37 1,28 1,24 1,09 1,24 1,02 0,89 1,15 1,29 0,82 1,22 1,32 1,37 1,28 1,27 1,27 1,14 1,26 1,24 1,19 1,02 1,09 0,78 0,94 0,9 1,00 1,27 1,27 1,14 1,26 05:28 10:53 16:20 21:47 02:43 05:27 05:28 10:53 Table 5. Measurement data value of roughness on speed the workpiece of 160 m/min,
depth of cut of
0.3
mm, and cutting speed
rotary tool
of
50
m/min.
No Speed
of
workpiece (Vw)
(m/min) Feed rate (f) (mm/rev) Depth of cut (d) (mm)
Speed of rotary
tool
(Vt) Surface roughness (µm) (m/min) 1 Ra 2 Ra 3 Ra Average (µm) Time (t) (Minute) 1 2 3 4 1 2 3 4 160 0.1 160 0.2 0.3 50 0.3 50 1,59 1,35 1,45 1,64 1,73 1,64 1,49 1,6 1,64 2,48 2,87 2,33 1,76 2,54 2,25 1,35 1,3 1,41 1,4 1,50 1,51 1,63 1,59 1,56 1,79 1,97 1,71 2,30 2,51 2,27 1,85 1,82 04:20 08:40 13:01 17:22 02:10 04:20 06:31 08:43 Table 6. Measurement data value of roughness on speed the workpiece of 80
m/min, feed rate of 0.15 mm/rev,
and
depth of cut 0.
3
mm.
No Speed of workpiece (Vw)
(m/min) Feed rate (f) (mm/rev) Depth of cut (d) (mm)
Speed of rotary
tool
(Vt) Surface roughness (µm) (m/min) 1 Ra 2 Ra 3 Average (µm) Ra Time (t) (Minute) 1 2 3 4 1 2 3 4 80 0.15 80 0.15 0.3 25 0.3 75 1,01 0,7 1,05 0,97 0,63 0,85 1,17 0,62 0,82 0,61 0,76 0,88 0,84 0,7 0,95 0,84 0,95 0,89 0,91 0,98 0,69 0,72 0,95 0,91 0,97 0,80 0,83 0,82 0,77 0,77 0,66 0,82 06:37 13:15 19:53 26:29 06:38 13:15 19:54 26:30 Table 7. Measurement data value raughness on the
feed rate 0.
15
mm/rev, depth of cut 0.
3
mm, and cutting speed
of rotary tool of 25 m/min No Speed of workpiece (Vw)
(m/min) Feed rate (f) (mm/rev) Depth of cut (d) (mm)
Speed of rotary
tool
(Vt) Surface roughness (µm) (m/min) 1 Ra 2 Ra 3 Ra Average (µm) Time (t) (Minute) 1 2 3 4 1 2 3 4 80 0.15 160 0.15 0.3 25 0.3 25 1,01 0,7 1,05 0,97 0,73 0,85 1,17 0,62 1,81 0,7 1,64 1,6 2,06 1,44 1,19 1,74 0,95 0,89 0,91 0,98 0,89 0,82 0,95 0,91 1,6 1,37 1,49 1,58 1,38 1,63 1,53 1,49 06:37 13:15 19:53 26:29 02:53 04:46 07:39 10:32 3.1. Feed rate and surface roughness value The following is a graph showing the comparison surface roughness values between
feed rate 0.1 mm/rev and 0.2 mm/rev
at
the depth of cut
(d) 0.3 mm. Figure 3. Comparison of surface roughness between
feed rate 0.
1
and 0.2 mm/rev.
Figure 3 is a comparison of
the effect of feed rate on the
value of
surface roughness.
Where in graph
1 surface roughness value
was lower than
in the
feed rate of 0.2 mm/rev.
It
is
inversely proportional
to
the statement earlier researchers [7]. Which states that the chip of feed is very influential on the surface roughness, where the greater the price of feed. the greater the level of coarseness. But in general, the value of the surface roughness is influenced by a variety of many factors. These factors include other parameters of the machining process, the condition
of the tool, the workpiece and the cutting
phenomenon [13] [14]. From the statement of course in this case the value of the feed is not completely affect the value of the resulting roughness. Whereas in Figure 2 the surface roughness value was lowest in
the feed
rate
0.1 mm/rev. In both
cases carried out observations of the surface profile, wherein the surface profile measurements to feed mark the resulting on cutting scars. Here is a comparison of the measured surface profile of the workpiece : Figure 4. Comparison between profiles of
feed rate (f) 0.1 and 0.2 mm/rev.
In Figure 4 obtained value feed mark on the first surface profile of
feed rate 0.1 mm/rev
of
0.
164
mm
and
feed rate 0.
2
mm/rev
of
0.
158
mm. While the
second profile
feed rate 0.1 mm/rev
produce value feed mark of 0.082
mm and feed rate 0.2 mm/rev
of 0.173 mm. 3.2. Cutting speed Rotary and surface roughness value The following is a graph showing the comparison between
the surface roughness value
of
the cutting speed of rotary tool
of 25 m/min and 75
m/min with
the
depth of cut
(d)
0.3 mm
: Figure 5 . Graph comparison of
cutting speed of rotary tool
(Vt) of
the surface roughness
values. Figure 5 is a comparison of the effect of cutting speed rotary tool against the surface roughness values. Where is concluded that
the value of
the surface
roughness was
lowest in
the cutting speed of
rotary tool (Vt) 75
m/min
and
the surface roughness values
were highest in
cutting speed of rotary tool (Vt) 25 m/min.
As already stated by Doni [7], the greater the cutting speed of the rotary cutting tool resulting roughness value would be lower. For a comparison of the surface profile can be seen in Figure 6. Figure 6. Comparison between the profile cutting speed of rotary tool 25 and 75 m/min. 3.3. Workpiece speed and surface roughness value The following is a graph showing the comparison between the
value of the surface roughness
of
the speed the workpiece of 80 m/min
and 160
m/min with
the
depth of cut
(d)
0.3 mm:
Figure 7. Graph speed the workpiece (Vw) of the surface roughness values. Figure 7 is a comparison of
the effect of
speed
of
workpiece
on the
value of
surface roughness.
Where
is
concluded that the value of surface roughness
was lowest in
the
speed
of
workpiece of 80 m/min and
the highest surface roughness
values occur
at
the
speed of
workpiece 160 m/min. As stated by Fariza [15] in his study, the greater
the speed of workpiece
then
the
resulting
roughness value
will be
higher.
For a comparison of the surface profile can be seen in Figure 8. Figure 8. Comparison between the velocity profile speed of workpiece 80 and 160 m/min.. 4. Conclusions 1.
The average value of the lowest surface roughness
obtained
on the speed
of
the workpiece
(VW) to 80 m/min, cutting speed of rotary tool (Vt) of 50 m/min with feed rate 0.2 mm/rev and depth of cut 0.3 mm. While the average value of the highest surface roughness obtained on the speed of the workpiece (Vw) of 160 mm/min, the cutting speed of rotary tool (Vt) of 50 m/min with feed rate 0.2 mm/rev and depth of cut 0.3 mm. 2.
Values of surface roughness is
not uniform throughout
the
machining process, this is due
to tool wear is
not uniform along
the edge
of
the
rotary
cutting
tool. 3. Values of surface roughness parameters are more influenced by the speed of the workpiece (Vw) and the cutting speed of rotary tool (Vt). Higher
speed of the workpiece
(Vw) then
the surface roughness
of the resulting
higher.
Instead
higher cutting speed of rotary tool
(Vt)
then the
value of
the
resulting
surface roughness
is lower. 4. Turning process using a rotary tool and air cooling can be implemented in a lathe machining process AZ31 magnesium material for producing a lower roughness values compared to using a silent tool. References [1] Ibrahim G A 2014 Analisa Kekasaran Permukaan pada Pemesinan Paduan Magnesium. Jurusan Teknik Mesin. Universitas Lampung. Bandar Lampung [2] Blawert C, Hort N and Kainer K U 2004 Automotive Applications Of Magnesium And Its Alloys Trans Indian Inst. Met. Vol.57 No. 4 pp. 397- 408 [3] Harun S 2012 Peningkatan Produktifitas dan Pengendalian Suhu Pengapian Pemesinan Magnesium Dengan Sistem Pahat Putar (Rotary Tool System) dan Pendingin Udara (Air Cooling) Universitas Lampung. Bandar Lampung [4] Mahrudi H, and Burhanuddin Y 2013 Rancang Bangun Aplikasi Thermovision Untuk Pemetaan Distribusi Suhu Dan Permulaan Penyalaan Magnesium Pada Pembubutan Kecepatan Tinggi Jurusan Teknik Mesin Universitas Lampung, Bandar Lampung. [5] Bruni C, Forcellese A, Gabrielli F, and Simoncini M 2004 Effect Of Temperature, Strain Rate And Fibre Orientation On The Plastic Flow Behaviour And Formability Of AZ31 Magnesium Alloy Department of Mechanics Università Politecnica delle Marche Via Brecce Bianche Ancona 60131 Italy [6] Su Y, He H, Li L, Iqbal A, Xiao, M H Xu, S Qiu, B G 2007 Refrigerated Cooling Air Cutting Of Difficult-To-Cut Materials International Journal of Machine Tools & Manufacture 47 927 – 933 [7] Doni A R 2015 Analisa Nilai Kekasaran Permukaan Paduan Magnesium AZ31 Yang Dibubut Menggunakan Pahat Potong Berputar. Tugas Akhir Universitas Lampung. [8] Andriyansyah 2014 Pengaruh Parameter Pemotongan Terhadap Kekasaran permukaan Dalam Pengefreisan Magnesium Tersuplai Udara Dingin. Tugas Akhir. Universitas Lampung. [9] Akhmad Isnain P, Gusri A I, and Burhanuddin Y 2013 Unjuk Kerja Vortex Tube Cooler Pada Pemesinan Baja St41. Jurnal FEMA. Universitas Lampung [10] Paryanto R, an Tony S U 2012 Effect Of Air Jet Cooling On Surface Roughness And Tool Wear Jurnal Teknosains Universitas Diponegoro [11] Stejernstoft T 2004 Machining of Some Difficult-to-Cut Materials with Rotary Cutting Tools Stockholm The Royal Institute of Technology KTH. [12] Novriadi D 2016 Rancang Bangun Sistem Pahat Putar Modular (Modular Rotary Tool System) Untuk Pemesinan Alat Kesehatan Ortopedi Universitas Lampung Bandar Lampung [13] Benardos P G, and Vosniakos G C 2003 Predicting surface roughness in machining: a review International Journal of Machine Tools & Manufacture 43 833 – 844. [14] Salgado D R, Alonso F J, Cambero I, and Marcelo A 2009 In-process surface roughness prediction system using cutting vibrations in turning International Journal of Advance Manufacturing Technology 43 40 – 51. [15] Fariza F 2016 Evaluasi Dan Analisa Kinerja Sistem Pahat Putar Modular Untuk Pemesinan Peralatan Kesehatan Ortopedi Berbasis Material Titanium 6al-4v ELI Tugas Akhir. Universitas Lampung
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