0708-F-037 EFFECT TYPES OF COOLANT ON TOOL WEAR
AND SURFACE ROUGHNESS
LOH CHOON LEE
UNIVERSITI MALAYSIA PAHANG
UNIVERSITI MALAYSIA PAHANG
BORANG PENGESAHAN STATUS TESIS
JUDUL: EFFECT TYPES OF COOLANT ON TOOL WEAR AND SURFACE ROUGHNESS
SESI PENGAJIAN: 2008/2009
Saya LOH CHOON LEE (850329-02-5037)
(HURUF BESAR)
mengaku membenarkan tesis (Sarjana Muda / Sarjana / Doktor Falsafah)* ini disimpan di perpustakaan dengan syarat-syarat kegunaan seperti berikut:
1. Tesis ini adalah hakmilik Universiti Malaysia Pahang (UMP). 2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi
pengajian tinggi. 4. **Sila tandakan (√)
SULIT (Mengandungi maklumat yang berdarjah keselamatan atau
kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972)
TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh
organisasi / badan di mana penyelidikan dijalankan)
TIDAK TERHAD Disahkan oleh:
_________________________ __________________________ (TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)
Alamat Tetap:
No 685, TMN BERSATU , Mr. LEE GIOK CHUI 06600 Kuala Kedah, (Nama Penyelia) Kedah. Tarikh: __________________ Tarikh: ___________________
CATATAN: * Potong yang tidak berkenaan
** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali tempoh tesis ini perlu dikelaskan sebagai SULIT atauTERHAD. Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara Penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM).
√
SUPERVISOR DECLARATION
I hereby declare that I have read this report and in my opinion this report is sufficient in
term of scope and quality for the award of the degree of Bachelor of Mechanical
Engineering with Manufacturing Engineering.
Signature : …………………………
Name of Supervisor: Mr. LEE GIOK CHUI
Position : Lecturer of Faculty Mechanical Engineering
Date : ………………………....
Signature : …………………………
Name of Panel : PUAN SALWANI BINTI MOHD SALLEH
Position : Lecturer of Faculty Mechanical Engineering
Date : ………………………....
0708-F-037 EFFECT TYPES OF COOLANT ON TOOL WEAR
AND SURFACE ROUGHNESS
LOH CHOON LEE
A report submitted in partial fulfillment of
The requirements for the award of the degree of
Bachelor of Mechanical Engineering
With Manufacturing Engineering
Faculty of Mechanical Engineering
UNIVERSITI MALAYSIA PAHANG
NOVEMBER 2008
ii
STUDENT DECLARATION
I declare that this thesis entitled “Effect Types of Coolant on Tool Wear and Surface
Roughness” is the result of my own research except as cited in the references. The thesis
has not been accepted for my degree and is not concurrently candidature of any other
degree.
Signature : ………………………..
Name : LOH CHOON LEE
ID Number : ME05048
Date : ………………………..
iii
To my Beloved Mother and Father
CHEW AH LIAN
LOH SAM HOE
iv
ACKNOWLEDGEMENTS
I would like to acknowledge and extend our heartfelt gratitude to my supervisor Mr.
LEE GIOK CHUI, SMP, KMN; Lecturer of Faculty Mechanical Engineering for his
continues support, helpful advice and valuable guidance throughout my thesis. This thesis
could not have been done without Mr. LEE who not only served as my supervisor but also
encouraged and guide me through the writing up thesis process by giving his best effort. I
also wish to express my sincere appreciate to the lecturers, technical staffs of Faculty
Mechanical Engineering, University Malaysia Pahang for their teaching and help during
the period of the project.
I also wish to express sincere appreciation to all my friends for their advice to do
the study. I benefited greatly from the comments and wisdom these reviewers generously
shared with me.
Most importantly, I would like to thank to my family especially my parents, Mr.
LOH SAM HOE and Mrs. CHEW AH LIAN, have guided me throughout my life. They
have always sacrifices their time and continuous support me to achieve my dreams and
goals. I would like to thank them for all support and encouragement they done for me.
Besides that I also want to express my appreciation to my elder brother LOH CHOON EU
and my younger brother LOH CHOON ZHEE for giving their idea, support, and help
throughout this project. I truly could not have done my thesis without them.
v
ABSTRACT
Tool wear has been a critical issue in metal removal processes. In turning process, tool
wear can create parts that are out-of-tolerance and eventually cause tool failure. The
repetition of machining work that subjects on the tool tip interface to a range of cutting
environments to comparatively evaluate their effect on tool life. The efficiency of cutting
tools can be evaluated based on certain parameters such as flank wear, surface roughness
on the work piece, cutting forces developed and temperature developed at the tool chip
interface. The objective of this project is to determine the types of coolant influence on tool
wear and surface roughness during turning of low-carbon steel AISI 1018, cold drawn,
high temperature with carbide tool. Furthermore by using oil based coolant, water based
coolant, and air as the coolant on the machining process, the three types of coolant are
compared to evaluate the most effective coolant which resulting the less tool wear will be
the optimum coolant. Next, we were used IM 7000 series Image Analyzer to observe and
measure the tools wear microstructure occurs on the tool after the turning process by using
different types of coolant. For surface roughness test, we were tested on surface texture of
work pieces that have been machining using different types of coolant by using IM 7000
series PERTHOMETER. Then, the less surface roughness values were indicated the
optimum coolant. Lastly, we were be resulting the optimum coolant that suitable use for
the range of velocities from 400-600 m/min for material low-carbon steel AISI 1018, cold
drawn, high temperature. The result indicated in general, oil based coolant performed
better than other two coolants in reducing the tool wear and improving the surface finish.
Oil based coolant has been used as one of the cutting fluids in this work because of its
thermal and oxidative stability which is being comparable to other water based coolant and
air used in the metal cutting industry.
vi
ABSTRAK
Kehausan mata alat telah menjadi isu yang sangat kritikal dalam proses pelarik besi.
Dalam proses pengisaran besi, kehausan mata alat boleh menyebabkan ketidakstabilan
hingga merosakan mata alat. Pengulangan proses pelarik besi yang tumpu di atas mata alat
bergantung kepada proses pemotongan besi yang akan memberikan kesan kepada jangka
hayat mata alat. Kecekapan mata alat boleh dinilai dengan pelbagai parameter seperti
kehausan sisi mata alat, kekasaran permukaan specimen, daya pemotongan yang dihasilkan
dan kenaikan suhu di mata alat. Objektif projek ini adalah untuk mencari jenis-jenis cecair
penyejuk yang akan menjejaskan kehausan mata alat dan kekasaran specimen semasa
proses pelarik aloi besi AISI 1018, dengan mengunakan mata alat carbide. Selain itu,
projek ini telah mengunakan cecair penyejuk seperti minyak, air, dan udara dalam proses
pelarik besi. Pembandingan ketiga-tiga jenis cecair penyejuk dikaji untuk mendapatkan
cecair penyejuk yang optimal iaitu cecair penyejuk yang dapat memberikan hasil kehausan
mata alat yang minimal dan kelicinan pada permukaan sepecimen. Kemudian, kehausan
mata alat akan diukur dan dilihat dengan mengunakan “IM 7000 series Image Analyzer”
manakala, kekasaran permukaan specimen akan diukur dengan mengunakan “Perthometer”.
Akhirnya, cecair penyejuk yang dapat menberi kehausan mata alat yang sikit dan
kekasaran permukaan specimen yang licin dalam julat kelajuan 400-600m/min semasa
proses pelarik aloi besi AISI 1018 adalah cecair penyejuk yang optimal. Keputusan projek
ini menunjukkan minyak sebagai cecair penyejuk lebih bagus berbanding dengan air dan
udara kerana kestabilan pengoksidaan dan konduksi haba yang bagus untuk kegunaan
dalam industri besi.
vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
TITLE i
STUDENT’S DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENTS iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii, viii, ix
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF SYMBOLS/ ABBREVIATIONS xii
LIST OF APPENDICES xiii
CHAPTER 1 INTRODUCTION
1.1 Introduction 1
1.2 Project Background 1
1.3 Problem Statement 2
1.4 Project Objective 3
1.5 Scope of Project 3
1.6 Summary 3
viii
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 4
2.1.1 Coolant for metal working 5
2.1.2 Types of coolant 6
2.2 Chip Formation 7
2.2.1 Types of chip formation 8
2.3 Tool Wear 9
2.4 Surface Roughness 10
2.5 IM 7000 series Image Analyzer 11
2.6 Summary 11
CHAPTER 3 METHODOLOGY
3.1 Introduction 12
3.2 Methodology Flow Chart 13
3.3 Gather Information 14
3.4 Identify Problem 15
3.5 Surface Roughness and Tool Wear test 15
3.5.1 Surface Roughness test on work pieces 16
3.5.2 Tool Wear image test on cutting tool 16
3.6 Propose Taguchi’s DOE by using Orthogonal Array 17
3.7 Expected Output 18
3.8 Documentation 19
3.9 Summary 20
ix
CHAPTER 4 RESULTS & DISCUSSION
4.1 Introduction 21
4.2 Analysis of variance (ANOVA) 22
4.3 Optimum coolant with respect to Surface Roughness 23-24
4.4 Optimum coolant with respect to Tool Wear 25-26
4.5 Validation Test 27-33
4.6 Summary 27
CHAPTER 5 CONCLUSIONS & RECOMMENDATION
5.1 Introduction 34 5.2 Conclusion 34 5.3 Recommendation 35 REFERENCES 36-37 APPENDIX A-E 38-44
x
LIST OF TABLE
Table No. Page
2.1 Classification of aqueous fluids for metal working (family M) 5
3.6 Orthogonal Array design table 17
4.1 ANOVA for Tool Wear, VB 22
4.2 ANOVA for Surface Roughness, Ra 22
4.3 Validation Test Result 27
xi
LIST OF FIGURES
Figure No. Page
2.1 Types of chip formation 8-9
2.2 The surface structure after cutting process 10
3.1 Methodology flow chart 13-14
3.2 Wear forms on turning tools at reusable state 15
4.1 Graph of Surface Roughness, Ra versus Cutting Speed, VC 24
4.2 Graph of Surface Tool Flank Wear, VB versus Cutting Speed, VC 26
4.3 Tool flank wear vs. cutting speed with respect to Oil 28
4.4 Tool flank wear vs. cutting speed with respect to Water 29
4.5 Tool flank wear vs. cutting speed with respect to Air 30
4.6 Surface roughness vs. cutting speed with respect to Oil 31
4.7 Surface roughness vs. cutting speed with respect to Water 32
4.8 Surface roughness vs. cutting speed with respect to Air 33
xii
LIST OF SYMBOLS/ ABBREVIATIONS
f Feed Rate, mm/rev
d Depth of Cut, mm
VC Cutting Speed, m/min
VB Flank wear, µm
C Coolant
Ra Surface Roughness, µm
N Total number of element
SEM Scanning Electron Microscope
DOE Design of Experiment
r Cutting Ratio
ф Shear angle
α Rake angle
P Probability
F F-test ANOVA
R2 coefficient of determination
xiii
LIST OF APPENDICES
Appendix Title Page
A Tool Wear Image 38
B Experiment data collection Orthogonal Array design table 39
C Experiment data addition for Minitab analysis table 40
D ANOVA result from Minitab 41-43
E Validation Test calculation from Trend line equation 44
CHAPTER 1
INTRODUCTION
1.1 Introduction
This chapter gives a short description of the project background including several
approaches. It then introduces objectives, scopes, problem statement of this project on
effect of coolant on lathe cutting tool life.
1.2 Project Background
Tool wear and breakage has been an issue with cutting tools since they were
created. Tool wear weakens the cutting tool, increases the forces used in cutting and causes
a lack of consistency in material removal. Parts and time lost to scrap and rework from tool
wear are costly to companies. Companies spend money to grind and replace cutting tools
due to tool wear. There are many factors that contribute to the wear of cutting tools: the
work pieces properties, cutting tool properties, cutting surface speed, cutting feed rate,
depth of cut and machine rigidity. Traditionally, cutting fluids have been seen as a solution
rather than a problem in metal cutting. They have proven to be a significant benefit to the
metal cutting process and do have an important role in improving and maintaining surface
finish, promoting swarf removal, cutting force reduction, size control, dust suppression,
and corrosion resistance to the work and the machine tool [1]. The damage experienced by
a cutting tool is influenced by the magnitude of stress and temperature at the tool chip
interface. Factors such as the interaction between cutting tool and material being cut,
2
cutting speed, feed rate, depth of cut, continuous or intermittent cutting, and the presence
of cutting fluid and its type, will influence the damage or wear rate of a cutting tool. The
way in which cutting fluids work and assist the cutting process is complex and is the
subject of long-standing research [2], [3] and [4] and in many instances the use and
adoption of cutting fluids has been an automatic choice based on the assumption that they
are essential for reliable and predictable machining processes.
By comparing the three coolants that is oil, water based coolant, and air; to
determine which one would be the most effective coolant for heat removal from the cutting
tool. Then, we will compare the three coolants by using the IM 7000 series IMAGE
ANALYZER to see the internal structure that changes have any wear occurs and we may
choose the optimal coolant for directly reduce the shortage of tool life. In order to support
my stand on the analysis of optimum coolant, surface roughness analysis is done by using
Perthometer to measure the work pieces after machining process. The optimal types of
coolants will be selected with regard to the performance indexes such as less tool wear on
the cutting tool and the minimum roughness of the surface texture for chip deformation are
considered. Finally, the paper concludes with a summary of this study and future work.
1.3 Problem Statement
Tool wear has been a critical issue in metal removal processes. In turning process,
tool wear can create parts that are out-of-tolerance and eventually cause tool failure.
The coolants uses in this project are oil, water based coolant, and air. Then,
compare the three types of coolant to evaluate which is the most effective coolant. IM 7000
series IMAGE ANALYZER is used to see the tools wear microstructure occurs on the tool
after the turning process. The less tool wear will result the optimum coolant.
Next, the work pieces that after machining with different types of coolant will be
compared by using surface roughness analysis on the surface texture produced. Then, the
less surface roughness values will indicate the optimum coolant.
3
1.4 Project Objective
The objectives of the project are to:
1. To determine the optimum coolant in order to decrease lathe cutting tool wear for
machining process.
2. To determine the optimum coolant on surface roughness of work pieces.
1.5 Scope of Project
In order to achieve the objectives of this project, the scopes are list as below:
1. Analysis and Evaluate on the tool wear and surface roughness by using the IM 7000
series IMAGE ANALYZER to measure the tool wear; and Mahrsurf XR 20
Perthometer S2 to measure the surface roughness after machining using different types
of coolants.
2. Using various types of the coolants such as oil based coolant, water based coolant, and
air on lathe machining.
3. For the turning process, the constant parameter such as work pieces use is low-carbon
steel AISI 1018, cold drawn, high temperature; depth of cut (1.0, 1.5, 2.0mm); amount
of coolant use; tool material CVD Coated Carbide Tips; feed rate (f = 0.20, 0.25, 0.28
mm/rev), and the range of cutting speed VC = (400,450,500,550,600m/min). But for the
non-constant parameter is types of coolant use are oil based coolant, water based
coolant, and air.
1.6 Summary
Chapter 1 has been discussed generally about project, problems statement,
objective and the scope of the project in order to achieve the objective as mention. This
chapter is as a fundamental for this project and as a guidelines to complete the project
research.
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
Any metal working fluid must satisfy certain fundamental requirements: removal of
heat; lubrication and transport of metal removed. The coolant systems for metal working
are typical example of a tribomechanical system, where several wear mechanisms are
present simultaneously. The metal particles in the coolant system have the appearance of
tiny chips, grains, coils of fine wire and so on. During the cutting process, the metal
working fluid is also exposed to changes due to tool surfaces and work pieces; the presence
of particles and high temperatures on contact surfaces. The changes can impair the
tribological properties and increase the risks associated with tribological processes on
machine tool elements.
In progress made by tribology during the past 25 years is indeed impressive, both in
the general as well as in the scientific and technological spheres. The important scientific
and technological achievements include: improved understanding of the role of lubricants
and of atmospheric environment in cutting and abrasive machining processes [5]. The
effectiveness of coolants has been studied in several projects and more detailed
explanations can be found in [6, 7, 8, 9 and 10].
5
2.1.1 Coolants for metal working
The recommendation of metal working fluids depends on the special application.
For applications where a metal working fluid with better lubricating properties is needed a
non-water-miscible fluid should be recommended (ISO-L-MHx) due to its better cooling
properties. The experimental investigations were carried out on lathes and the turning
conditions were determined using water based coolants. International Standard ISO 6743/7
establishes the detailed classification of family M (metal working) which belongs to the
class L (lubricants, industrial oils and related products) [11]. The first letter of the category
(M) identifies the family of the product considered but any following letters taken
separately have no significance on their own. Classifications of aqueous fluids for metal
working (family M) are shown in Table 1, where: A, code letter; B, particular application;
C, more specific application; D, product type and/or end requirements; E, symbol ISO-L.
Table 2.1: Classification of aqueous fluids for metal working (family M)
A B C D E
M
Metal removal by cutting or abrasion and metal forming by punching deep drawing, ironing, power spinning, wire drawing, forging-hot and cold, extrusion, stamping, rolling hot and cold
Operation primarily needing cooling
Concentrates giving, when blended with water, milky emulsion having anti-corrosion properties. Concentrates of MAA type having friction reducing properties. Concentrates of MAA type having extreme pressure (EP) properties Concentrates of MAB type having extreme pressure (EP) properties Concentrates giving, when blended with water translucent emulsions (micro emulsions) having anticorrosion properties. Concentrates of MAE type having friction reducing and/or extreme pressure (EP) properties. Concentrates of MAF type having friction reducing and/or extreme pressure (EP) properties. Concentrates of MAG type having friction reducing and/or extreme pressure (EP) properties. Concentrates of MAH type having friction reducing and/or extreme pressure (EP) properties.
MAA
MAB MAC MAD MAE
MAF
MAG
MAH
MAI
6
2.1.2 Types of coolant
Water based coolants are liable to undergo a number of changes during use with
respect to their composition and properties that can impair the functional properties and
increase the risks associated with abrasion, erosion and corrosion of tribomechanical
system elements. The main influential factors in the coolant system are: particles;
temperature; fluid composition and flow. The presence of particles has a negative influence
on surface quality, machine life, tool life, coolant life and for the health aspect.
The temperatures rise in coolants can be quite considerable, if the machine is of the
type where the coolant sump forms an integral part of the machine framework (individual
systems). The composition of a coolant changes during the use as a consequence of
vaporization of water and the removal of various other materials in the filtering process.
Depending on the relationship between these factors, these changes will thereby result in
either a concentration or a dilution of the fluid. With respect to the significant vaporization
that takes place, it is essential to monitor the quality of the water that is added to maintain
the correct dilution. The salt contents in tap water cause an accumulation of salts as more
water is added. The main undesirable consequence of a high salt content on the process is
excessive corrosion of tribomechanical system elements. The other influential factors are
free oils and microorganisms.
Free oil is a combination of “tramp oil” from the process machine’s lubrication and
drive systems; oil washed down from guide ways, rust inhibiting oil from work pieces and
oil resulting from emulsion breakdown. The presence of free oil on the coolant surface
results in a number of undesirable consequences for both the effectiveness of the process
and for the health aspect. Large numbers of microorganisms (bacteria and fungi) shorten
the coolants useful life to a considerable degree, as well as causing a number of technical
problems. Large concentration of microorganisms causes an accumulation of metabolic
organisms in the fluid, which can result in skin ailments.
7
2.2 CHIP FORMATION
2.2.1 Types of chip formation
There are three types of chips that are commonly produced in cutting,
· discontinuous chips
· continuous chips
· continuous with built up edge
A discontinuous chip comes off as small chunks or particles. When we get this chip it may
indicate,
· brittle work material
· small rake angles
· coarse feeds and low speeds
A continuous chip looks like a long ribbon with a smooth shining surface. This chip type
may indicate,
· ductile work materials
· large rake angles
· fine feeds and high speeds
· use of coolant and good chip flow
Continuous chips with a built up edge still look like a long ribbon, but the surface is no
longer smooth and shining. This type of chip tends to indicate,
· High friction between work and tool causes high temperatures that
will occasionally weld the chip to the tool. This will break free, but
the effect is a rough cutting action.
Continuous chips and subsequently continuous cutting action is generally desired.
8