UNIVERSITI TEKNIKAL MALAYSIA MELAKA SURFACE MODIFICATION OF LOW CARBON STEEL IN LASER CUTTING This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering (Manufacturing Process) with Honours. by LUEI HONG KEAT FACULTY OF MANUFACTURING ENGINEERING 2009
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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
SURFACE MODIFICATION OF LOW CARBON STEEL IN LASER
CUTTING
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Process) with Honours.
by
LUEI HONG KEAT
FACULTY OF MANUFACTURING ENGINEERING
2009
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: Surface Modification of Low Carbon Steel in LASER Cutting
SESI PENGAJIAN: 2008/09 Semester 2
Saya LUEI HONG KEAT
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Sila tandakan (√)
SULIT
TERHAD
TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
(TANDATANGAN PENULIS)
Alamat Tetap:
NO. 1 Persiaran Indah Rokam 1,
Taman Sri Rokam,
31350 Ipoh, Perak
Tarikh: _______________________
Disahkan oleh:
(TANDATANGAN PENYELIA)
Cop Rasmi: Tarikh: _______________________
** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
DECLARATION
I hereby, declare this report entitled “Surface Modification of Low Carbon Steel in Laser
Cutting” is the result of my own research except as cited in references.
Signature :
Author’s Name : LUEI HONG KEAT
Date : 18th
May 2009
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTEM as a
partial fulfilment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Manufacturing Process) with Honours. The member of the supervisory
committee is as follow:
…………………………..
i
ABSTRACT
Laser cutting is an advanced machining which becoming important for the industrial
application. The machine can do its jobs faster, more accurate and more complex shape
than other conventional machine and can machine a lot of materials available. The
demand of the modern material with high hardness leads to more difficult for machining,
laser cutting hereby solve the problems of this. In the research, surface modification of
the low carbon steel will be identify and observed after machining. By using sets of
parameters with different cutting speed and laser output power, the impact of this
parameter on the surface of cut will be investigate. Firstly is to do surface roughness test
on the machine surface of each samples. Then the sample will be mounted on epoxy to
be grind and polish, before observation under microscope, the sample undergoes etching.
Finally the cut surface grain structure is observed for microstructure changes of size.
Machine which in used for the experiment will be all located in the laboratory. In the
experiment, roughness test shows that the surface cut with the higher speed will have
higher value of roughness but when the speed is lower it will affect more heat to be
transfer on the material and causing heat affected zone to be increase in the size on the
surface. In other explanation will be the spreading of heat during laser decrease as the
laser beam does not stay longer a location.
ii
ABSTRAK
Pemotong laser merupakan mesin termaju dan semakin menjadi penggunaan yang
penting dalam aplikasi industri. Mesin laser mampu melakukan kerja-kerja pemotongan
dengan lebih cepat, tepat dan boleh memotong bentuk-bentuk yang kompleks
berbanding dengan mesin tradisional. Mesin laser juga dapat memotong pelbagai jenis
bahan yang terdapat di dunia ini. Dengan permintaan bahan yang berkekerasan yang
tinggi akan menyukarkan lagu pemotongan dengan menggunakan mesin tradisional,
dengan kewujudan mesin pemotong laser lalu menyelesaikan masalah ini. Dalam
penyelidikan ini, perubahan dalam permukaan yang dipotong oleh laser pada besi
berkandungan karbon rendah akan dikenalpasti dan diperhatikan selepas pemesinan.
Dengan menggunakan beberapa set parameter berlainan dalam mesin seperti perubahan
kelajuan memotong dan kuasa output laser. Impak pada permukaan dipotong akan dikaji.
Kajian pertama selepas pemesinan ialah ujian kekasaran pada setiap sempel.
Kemudiannya sempel akan disediakan dalam epoxy dan dikilatkan. Sebelum dilihat
melalui mikroskop, sempel akan dicelup dalam larutan nital untuk beberapa saat
sehingga seminit dan dibersih dan dikeringkan. Ujian kekasaran menunjukkan sekiranya
kelajuan laser meningkat akan menyebabkan bacaan kekasaran meningkat. Akan tetapi
melalui gambar dibesarkan dalam mikroskop semakin lambat kelajuan laser akan
menyebabkan HAZ tersebar lebih jauh. Dengan kata lain, sekiranya pancaran laser tidak
berada dalam kawasan dengan lama akan mengurangkan haba mengalir.
iii
DEDICATION
This work is dedicated to my beloved parents, Luei Heng Bee and Chan
Soo Mooi, without their caring support and the respect for education it
would not have been possible.
iv
TABLE OF CONTENT
Abstract i
Abstrak ii
Dedication iii
Table of Content iv
List of Tables vi
List of Figures viii
List Abbreviations xi
1. INTRODUCTION 1
1.1 Background 1
1.2 Problem Statement 3
1.3 Objectives 4
1.4 Scope 4
1.5 Significant of Study 5
2. LITERATURE REVIEW 6
2.1 Introduction to Laser Beam Machining 6
2.1.1 CO2 Laser Cutting 7
2.2 Laser Cutting Parameters 11
2.3 Surface Morphology 16
2.3.1 Laser Cutting 17
2.4 Summary 21
3. METHODOLOGY 22
3.1 Equipment In Used 22
3.2 Material 23
3.2.1 Low Carbon Steel 23
3.2.2 Composition 24
3.2.3 Physical Properties 24
3.2.4 Mechanical Properties 24
3.2.5 Thermal Properties 25
3.3 Flow Chart 25
3.4 Laser Cutting Machine LVD HELIUS 2513 26
3.4.1 Laser Hazard 28
3.5 Surface Roughness Tester Mitutoyo SJ-301 29
v
3.6 Metallographic Specimens Preparation 29
3.6.1 Selection of Specimens 30
3.6.2 Size of the Specimens 30
3.6.3 Cleaning of Specimens 31
3.6.4 Mounting of Specimens 32
3.6.5 Grinding and Polishing 34
3.6.6 Etching 37
3.7 Surface Modification Study 40
3.7.1 Roughness Test 42
3.7.2 Microscopic Examination with Optical Microscopy 42
3.7.3 Microscopic Examination with Electron Microscopy 44
3.8 Summary 45
4. RESULT AND DISCUSSION 46
4.1 Surface Roughness 46
4.2 Microstructure Examination 50
4.2.1 Size of HAZ 51
4.2.2 Microstructure Observation 54
4.3 Summary 63
5. CONCLUSION AND SUGGESTION 64
5.1 Conclusion 64
5.2 Recommendation for Future Study 65
5.3 Summary 66
REFERENCES 67
APPENDICES
A Surface Roughness Result
B Gantt chart for PSM 1
C Gantt chart for PSM 2
vi
LIST OF TABLES
2.1 Type of laser used on metal, plastic and ceramics
(Kalpakjian and Schmid, 2006) 6
2.2 Laser cutting parameters (Yilbas, 1994) 14
3.1 Chemical composition 23
3.2 Density 23
3.3 Mechanical Properties 23
3.4 Thermal Properties 24
3.5 Machine Specification 25
3.6 Parameters for the 4 samples 26
3.7 Mounting Compound 32
3.8 Size range for ANSI/CAMI graded paper 34
3.9 Microetching etchant and procedure (ASTM E407 – 99) 36
3.10 Macroetchant etchant and procedure (ASTM E340 – 00) 38
4.1 Names of samples based on its parameters 45
vii
4.2 Roughness test results 46
4.3 Size of HAZ 52
viii
LIST OF FIGURES
2.1 Gas assists in laser cutting (Radovanic and Dasic, 2006). 9
2.2 Cutting rates for CO2 Laser. 12
2.3 Surface roughness in dependence on sheet thickness
(Radovanic and Dasic, 2006). 13
2.4 Experiment set up (Yilbas, 1994). 14
2.5 Spiral cut (Yilbas, 1994). 15
2.6 Picture and profile of laser cut (Radovanic and Dasic, 2006). 18
2.7 Laser cut surface (Radovanic and Dasic, 2006). 18
2.8 Cross section cut at low speed 2 cm/s, O2 gas pressure 140 kPa
(Yilbas, 1994). 20
2.9 Cross section cut at moderate speed 4 cm/s, O2 gas pressure 140 kPa
(Yilbas, 1994). 20
2.10 Cross section cut at high speed 6 cm/s, O2 gas pressure 140 kPa
(Yilbas, 1994). 20
3.1 Flow chart of experiment. 24
3.2 Laser cutting machine. 26
3.3 Roughness tester. 28
3.4 Method of designing location of area shown in photomicrograph.
(ASTM E3 – 01, 2007). 30
3.5 METKON mounting press. 33
ix
3.6 Grinding machine 34
3.7 Polishing machine 35
3.8 Aluminium Oxide Powder 35
3.9 Flow chart for surface modification study 40
3.10 Normal incident light being reflected by three etched surface grains
by having different orientation each. (Callister, 2005). 42
3.11 Surface structure which might appear when view with microscope; luster
or texture of each grain depends on reflectance properties.
(Callister, 2005). 42
3.12 Section of grain boundary and the surface groove produce when etching.
(Callister, 2005). 42
3.13 Photomicrograph of polycrystalline specimen. (Callister, 2005). 43
4.1 Surface roughness graph. 46
4.2 Laser beam melts and vaporized material, creating a kerf.
(Laser cutting guide for manufacturing, 2003). 48
4.3 Surface of sample S1 after Laser cut. 48
4.4 Surface of sample S2 after Laser cut. 48
4.5 Surface of sample S3 after Laser cut. 49
4.6 Surface of sample G after Laser cut. 49
4.7 Size of HAZ 52
4.8 Microstructure of sample S1 etches with 2% Nital. 50X magnification. 53
4.9 Microstructure of sample S2 etches with 2% Nital. 50X magnification. 54
4.10 Microstructure of sample S3 etches with 2% Nital. 50X magnification. 54
x
4.11 Microstructure of sample G etches with 2% Nital. 50X magnification. 55
4.12 Iron-carbon phase diagram.
(ASM Handbook Volume 9 Metallography and Microstructure) 56
4.13 Microstructure of sample S1 etches with 2% Nital. 100X magnification. 57
4.14 Microstructure of sample S1 etches with 2% Nital. 200X magnification. 57
4.15 Microstructure of sample S2 etches with 2% Nital. 100X magnification. 58
4.16 Microstructure of sample S2 etches with 2% Nital. 200X magnification. 58
4.17 Microstructure of sample S3 etches with 2% Nital. 100X magnification. 59
4.18 Microstructure of sample S3 etches with 2% Nital. 200X magnification. 59
4.19 Microstructure of sample G etches with 2% Nital. 100X magnification. 60
4.20 Microstructure of sample G etches with 2% Nital. 200X magnification. 60
4.21 Microstructure of sample S1 etches with 2% Nital. 500X Magnification. 61
4.22 Microstructure of sample S2 etches with 2% Nital. 500X Magnification. 61
4.23 Microstructure of sample S3 etches with 2% Nital. 500X Magnification. 62
4.24 Microstructure of sample G etches with 2% Nital. 500X Magnification. 62
A Surface roughness result of sample S1 and S2.
B Surface roughness result of sample S3 and G
xi
LIST OF ABREVIATIONS
AC - Alternative current
CNC - Computer numerical control
CW - Continuous Wave
DC - Direct current
EDM - Electrical discharge machining
HAZ - Heat affected zone
LBM - Laser beam machining
LGAC - Laser generated air contaminant
OEM - Original Equipment Manufacturer
SEM - Scanning electron microscope
TEM - Transmission Electron Microscope
UV - Ultra-Violet
YAG - Yttrium Aluminium Garnet
1
CHAPTER 1
INTRODUCTION
This chapter will briefly explain about the research and what is the current
motivation that brings out the idea to study on the laser beam machining and
machining effect on the workpiece.
1.1 Background
In the world of today, metal working operation is a common process to human being,
but the requirements for high accuracy and precision going higher and higher each
day to enable new possible product is being produce with various kind of geometrical
shape. As the manufacturing tends to become more and more complex, more
technology will be invented and implemented. If there is possibility human tends to
produce machining operation which will not need additional machining process in
order to give a better finishing. The reason behind is to have lower cost in the
production, fewer machining operation or finishing operation will reduce the cost of
product being manufactured. Sometimes there are some circumstances which cause
the manufacturing process to be increase, such as the complexity where one
machining process cannot do all the profile or maybe there is needed to have tools
change whenever removing material of different profile. There are also additional of
time when there is a need of changing tool or even changing of machining processes
which also means change of workstation. When this happens, lead time to the next
process will be increases. Non-traditional machining process created is not only to
fulfilled the reason on increasing performance of certain manufacturing process but
there is a need to taken in account on how the effect of machining processes affect on
2
the workpiece especially when heat generated which there is a high possibility
altering the properties of the material which it used to be. On the second though
material nowadays required on better quality with high hardness, toughness and
impact resistance leads to an increasing of difficulty in cutting this type of material.
But still there is a need on new material being created, which is to suits the current
manufacturing work. Conventional machined unable to cut any material which is
harder than its cutting tool but with existents of modern machining is used such as