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