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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
SURFACE FINISH STUDY OF MILD STEEL MACHINED BY
CARBIDE CUTTING TOOLS
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
MOHD FAIZAL BIN MOHAMAD
FACULTY OF MANUFACTURING ENGINEERING 2010
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 404, Blok 17, F. Keratong 7,
26700 Muadzam Shah,
Pahang Darul Makmur.
Tarikh:
Disahkan oleh:
(TANDATANGAN PENYELIA)
Cop Rasmi:
Tarikh: _______________________
* Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertai bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM). ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.
BORANG PENGESAHAN STATUS TESIS*
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
JUDUL: Surface Finish Study of Mild Steel Machined by Carbide Cutting Tools
SESI PENGAJIAN: 2009/2010
Saya _______ MOHD FAIZAL BIN MOHAMAD__________ mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran
antara institusi pengajian tinggi.
4. **Sila tandakan (√)
(HURUF BESAR)
ii
DECLARATION
I hereby declare that this report entitled “SURFACE FINISH STUDY OF MILD
STEEL MACHINED BY CARBIDE CUTTING TOOLS” is the results of my own
research except as cited in references.
Signature :
Author’s Name : MOHD FAIZAL BIN MOHAMAD
Date :
iii
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Manufacturing Process) with honour. The members of the supervisory
committee are as follow:
…………………………………………….
MR. SHUKOR BIN SALLEH (PSM Supervisor)
iv
ABSTRACT
The main goal of this project is to analyze the effects of the parameters on surface
roughness in turning process. Generally there are three parameters that will affect the
surface roughness which are cutting speed, feed rate and depth of cut. Roughness is a
measure of the texture on a surface. It is quantified by the vertical deviations of a real
surface from its ideal form. If these deviations are large, the surface is rough and if it is
small the surface is smooth. Surface roughness constitutes one of the most critical
constraints for the selection of machine tools and cutting parameters in metal cutting
operations. In this study, the Taguchi’s method was used to study the effects of cutting
parameters which are cutting speed, feed rate and depth of cut. The material used in this
research was mild steel AISI 1020. Machining trials was conducted at different cutting
conditions using carbide cutting tools. Surface roughness values were measured using
surface roughness tester. It was shown that feed rate was given the highest influence of
the surface roughness. The study is importance to machinist in the selection of
appropriate combinations of machining parameters for high-speed turning of mild steel
AISI 1020 workpiece using carbide cutting tool. The experimental results reveal that the
most significant machining parameter for surface roughness is feed rate followed by
depth of cut and cutting speed.
v
ABSTRAK
Matlamat utama projek ini adalah untuk menganalisis kesan parameter terhadap
kekasaran permukaan produk semasa proses melarik. Umumnya terdapat tiga parameter
yang member kesan kepada kekasaran permukaan dimana ianya adalah halaju
pemotongan, kadar suapan dan kedalaman pemotongan. Kekasaran ialah pengukuran
tekstur sesuatu permukaan. Kekasaran permukaan merupakan salah satu perkara yang
paling penting untuk pemilihan peralatan mesin dan parameter permotongan dalam
operasi pemotongan logam. Di dalam kajian ini, ‘Taguchi method’ akan digunakan
untuk mengkaji kesan parameter pemotongan dimana ianya adalah halaju pemotongan,
kadar suapan dan kedalaman pemotongan ke atas kekasaran permukaan benda kerja
yang akan dimesin di mana ianya adalah ‘mild steel AISI 1020’. Pemesinan yang akan
dijalankan mengikut parameter pemotongan yang berbeza menggunakan alat pemotong
karbida. Nilai kekasaran permukaan akan diukur menggunakan penguji kekasaran
permukaan. Hasil daripada kajian ini menunjukkan kadar suapan memberikan kesan
yang paling tinggi terhadap kekasaran permukaan benda kerja. Kajian ini penting kepada
operator pemesinan untuk memilih kombinasi parameter mesin yang sesuai di dalam
pemesinan kelajuan tinggi terhadap benda kerja iaitu ‘mild steel AISI 1020’
menggunakan alat pemotong karbida. Hasil daripada kajian ini menunjukkan bahawa
kadar suapan memberikan kesan yang paling besar diikuti oleh kedalaman pemotongan
dan halaju pemotongan.
vi
DEDICATION
To my dearest parents, Mohamad Bin Md. Saman and Zaliha Binti Ismail
for their love, care and supports.
vii
ACKNOWLEDGEMENT
In the Name of ALLAH The Most Gracious, Most Merciful
First of all, thanks to ALLAH S.W.T for giving me the strength and patience in order to
accomplish the research of my final year project.
I would like to express my deepest appreciation to my supervisors, Mr. Shukor
bin Salleh for the guidance, encouragement, and feedback he provided to me during the
final year project process.
I especially would like to thank my mother, brother and sisters for their support
and encouragement. Lastly, I would like to thank everyone who directly or indirectly
involved through contribution of ideas, materials, as well as professional opinions until
this project had been successfully done.
viii
TABLE OF CONTENTS
Declaration ii
Approval iii
Abstract iv
Abstrak v
Dedication vi
Acknowledgement vii
Table of Contents viii
List of Figures iv
List of Tables v
List of Abbreviations, Signs, and Symbols vi
CHAPTER 1: INTRODUCTION 1
1.1 Background of Project 1
1.2 Problems Statements 6
1.3 Objectives of Project 7
1.4 Scope of Project 7
1.5 Report Outline 8
1.6 Gantt Chart 9
CHAPTER 2: LITERATURE REVIEW 11
2.1 Introduction 11
2.2 Machining Process 13
2.2.1 Type of Metal Cutting 12
2.2.1.1 Types of Production 14
2.2.2 CNC Lathe Machine 15
2.2.3 Automatic Tool Changers 15
2.2.4 Manual Tool Changing 16
ix
2.3 Cutting Tool Material 16
2.3.1 Carbide Inserts Turning 17
2.4 Machining Parameters 17
2.4.1 Cutting Speed 17
2.4.2 Feed Rate 18
2.4.3 Depth of Cut 19
2.5 Surface Roughness 22
2.5.1 Introduction of Surface Metrology 24
2.5.2 Roughness 25
2.5.3 Waviness 25
2.5.4 Method to Analyze Surface Roughness 25
2.5.4.1 Average Roughness (Ra) 25
2.6 Cutting Fluids 27
2.6.1 Functions of Cutting Fluids 27
2.7 Taguchi’s Method 28
2.8 Prediction the Result by Pass Research about the Surface Integrity 30
CHAPTER 3: METHODOLOGY 32
3.1 Introduction 32
3.2 Planning 33
3.3 Selection of Machine and Equipment 33
3.3.1 Selection of Machine 33
3.3.1.1 CNC Lathe Machine 33
3.4 Selection of Workpiece Material 36
3.4.1 Mild Steel 36
3.5 Selection of method for Analysis 38
3.5.1 Method to Analyze Surface Roughness 38
3.5.2 Surface Roughness Measurement 40
3.5.3 Surface Roughness Tester (SJ-301) Procedure 41
x
3.6 Experiment Procedure 41
3.6.1 Experimental Design 41
3.6.2 Cutting Parameters 42
3.6.3 Experiment Flowchart 44
3.7 Lab Sheet Design 45
CHAPTER 4: RESULTS AND ANALYSIS 46
4.1 Introduction 46
4.2 Design of Experiment 47
4.3 Findings and Data Analysis of Surface Roughness 48
4.3.1 Interaction Plot for SN ratios (Feed Rate) 49
4.3.2 Interaction Plots for SN ratios (Depth of Cut) 50
4.3.3 Effect of Control Parameters on Surface Roughness 51
4.3.4 ANOVA Table for response function of the surface roughness 54
4.4 Predicted Result at Optimum Setting Condition 55
4.4.1 Confirmation Test 55
4.4.2 Comparison Test Result 56
CHAPTER 5: DISCUSSION 57
5.1 Introduction 57
5.2 Machining Parameter Analysis 58
5.3 Surface Roughness Analysis 58
5.3.1 Feed Rate 59
5.3.2 Cutting Speed 59
5.3.3 Depth of Cut 60
5.3.4 Other Factors 61
CHAPTER 6: CONCLUSION AND RECOMMENDATION 62
6.1 Conclusion 62
6.2 Recommendation 63
6.2.1 Workpiece 63
xi
6.2.2 Machine 63
6.2.3 Cutting Tool 63
6.2.4 Design of Experiments 64
6.2.5 Mathematical Modeling 64
REFERENCES 65
xii
LIST OF FIGURE
Figure
1.1
1.2
2.1
2.2
2.3
3.1
3.2
3.3
3.4
3.5
3.6
4.1
4.2
4.3
Description
Conventional lathe
CNC turning machine Surface roughness profile
Roughness, waviness, lay and flaw
Average roughness (Ra)
Project flowchart
HAAS CNC lathe machine
Mild steel AISI 1020
Portable surface roughness tester
Distance of measurement on top surfaces in plan view of test
piece
Flow chart for experiment procedure
Interaction Plot for SN ratios (Feed Rate)
Interaction Plot for SN ratios (Depth of Cut)
Mean S/N Graph for Surface Roughness
Page
3
4
23
24
26
34
35
36
38
40
44
49
50
53
xiii
LIST OF TABLE
Table
1.1
1.2
2.1
2.2
3.1
3.2
3.3
3.4
3.5
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
Description
Gantt chart for PSM 1
Gantt Chart for PSM 2
Suggested operating parameters for machining various materials
with carbide tools
General recommendations for turning operations
Composition of AISI standard mild steel AISI 1020
Mechanical properties of mild steel at room temperature
General specification of Mitutoyo surface roughness tester
Cutting parameters
Cutting conditions and response
Variable levels used in the experimentation
Experimental result for surface roughness
Types of Characteristics and Formula
Response Table for Signal to Noise Ratios Smaller is better
ANOVA table for response function of the surface roughness
Factors levels for prediction
Confirmation test results
Comparison of predicted and experimented results
Page
9
10
20
21
37
37
39
42
42
47
48
51
52
54
55
55
56
xiv
LIST OF ABBREVIATIONS, SIGNS, AND SYMBOLS
AISI - American Iron and Steel Institute
C - Carbon
Cu - Cooper
FKP - Fakulti Kejuruteraan Pembuatan
Mn - Manganese
P - Phosphorus
PSM - Projek Sarjana Muda
Ra - arithmetic mean value (roughness average)
Rpm - revolution per minute
Rq - root mean square average
S - Sulfur
UTeM - Universiti Teknikal Malaysia Melaka
USA - United State of America
ATC - Automatic tool changer
CNC - Computer Numerical Control
AA - Arithmetic average
CLA - Center line average
ANOVA - Analysis of Variances
1
CHAPTER 1 INTRODUCTION
1.1 Background of Project
Surface roughness and tolerances are among the most critical quality measures in many
mechanical products. As competition grows closer, customers have increasingly focused
on quality, making surface roughness become one of the most competitive dimensions in
today’s manufacturing industries. Surface of a mechanical product can be created with a
numbers of manufacturing processes.
Surface roughness is an important measure of the technological quality of a product and
a factor that greatly influence manufacturing costs. The mechanism behind the formation
of surface roughness is very dynamic, complicated and process dependent and it is very
difficult to calculate its value through theoretical analysis.
Mild steel is used in this project which sometimes it referred to as 'carbon steel' or 'plain
carbon steel'. Carbon steel makes up the largest part of steel production and is used in a
vast range of applications. As others material, it also have its own advantages which are
cheap, high stiffness, strong, magnetic and most of it are easy machine and weld.
However, this material also has its own disadvantage which is poor corrosion resistance.
2
This research applies Taguchi’s method approach to studying the impact of turning
parameters on the roughness of turned surfaces. Taguchi’s method approach is quality
control methodology that combines control charts and process control with product and
process design to achieve a robust total design. It aims to reduce product variability with
a system for developing specifications and designing them into a product or process.
Named after its inventor, the Japanese engineer-statistician Dr. Genichi Taguchi who
also developed the quality loss function.
Taguchi Method is a process or product optimization method that is based on 8-steps of
planning, conducting and evaluating results of matrix experiments to determine the best
levels of control factors. The primary goal is to keep the variance in the output very low
even in the presence of noise inputs. Thus, the processes or products are made robust
against all variations.
A metal lathe or metalworking lathe is a large class of lathes designed for precisely
machining relatively hard materials. They were originally designed to machine metals;
however, with the advent of plastics and other materials, and with their inherent
versatility, they are used in a wide range of applications, and a broad range of materials.
In machining jargon, where the larger context is already understood, they are usually
simply called lathes, or else referred to by more-specific subtype names such as
toolroom lathe, turret lathe and etc. These rigid machine tools remove material from a
rotating workpiece via the movements of various cutting tools, such as tool bits and drill
bits.
3
Turning is one of the most commonly used processes where metal is removed by
rotating the wokpiece with respect to a tool. The workpiece is held in a chuck that is
clamped to the spindle. The tool is held in a tool post that is mounted on a cross slide,
which provides radial tool movement. If the workpiece is long, both of the ends are held
by the chuck and tailstock. The cross-slide is held on the top of a carriage that has
motion along the axis between spindle and tailstock centers. Conventional lathes have
single motor that rotates the spindle via gearbox and belts (Figure 1.1).
Figure 1.1: Conventional lathe (Bulent, 2002)
CNC is the process of manufacturing machined parts. Numerical Control (NC) is the
original name given to this technology and is still often used interchangeably with CNC.
NC technology has been one of manufacturing's major developments in the past fifty
years. It not only resulted in the development of new manufacturing techniques and the
achievement of higher production levels, but it also helped increase product quality and
stabilize manufacturing costs (Ismail, 2002).
4
Due to the increasing demand of precision parts and devices in many industries such as
optics, computers, automotive and aerospace etc, it may, in general, be possible to
achieve the required precision operations at high accuracy by using expensive
manufacturing equipments. In addition to these costly equipments, using a secondary
finishing operation such as grinding or polishing may significantly reduce the
productivity and introduce set-up errors. There are some ultra precise turning machines,
which can produce parts at micro level accuracy. Special machine tool manufacturers
produce these machines. But they are very costly compared to standard machine tools
used in the industry. These turning machines have to be operated in a temperature
controlled, vibration free and stable environment.
In CNC (Computer Numerical Control) turning machines, unlike conventional ones, the
feed and spindle speeds are programmed within computer programs (Figure 1.2). In
these machines, the turret holds the tools. The turret may contain multiple 6 until 12
cutting tools.
Figure 1.2: CNC turning machine (Bulent, 2002)
5
CNC lathes are rapidly replacing the older production lathes due to their ease of setting
and operation. They are designed to use modern carbide tooling and fully utilize modern
processes. The part may be designed and the toolpaths programmed by the CAD/CAM
process, and the resulting file uploaded to the machine, and once set and trialled the
machine will continue to turn out parts under the occasional supervision of an operator.
The machine is controlled electronically via a computer menu style interface, the
program may be modified and displayed at the machine, along with a simulated view of
the process. The setter needs a high level of skill to perform the process, however the
knowledge base is broader compared to the older production machines where intimate
knowledge of each machine was considered essential. These machines are often set and
operated by the same person, where the operator will supervise a small number of
machines. The design of a CNC lathe has evolved yet again however the basic principles
and parts are still recognizable, the turret holds the tools and indexes them as needed.
The machines are often totally enclosed, due in large part to Occupational health and
safety (OH&S) issues.
Since the introduction of the first NC machine, there have been many applications of NC
machining technology such as, turning, grinding, drilling, flame and laser cutting,
forming and bending, punching and nibbling, electric discharge machining. In NC there
are many sources and look-up tables available for selecting these correct parameters. For
turning, the diameter of the workpiece and the surface feet per minute for the material
are factors in determining the proper speeds and feed rates (Ismail, 2002).
The important parameters of turning machines are spindle speed, feed rate, depth of cut
and tool geometry such as rake face and clearance face. Spindle speed is the angular
speed of the rotating workpiece. Feed rate is the distance moved by the tool in an axial
direction for each revolution of the workpiece. Depth of cut is the thickness of metal
removed from the workpiece measured in a radial direction.
6
The present work concerns with the optimization of the machining parameters in CNC-
Turning machine, and study their effects on the surface roughness of mild steel
workpiece. The evaluations are defined from the experiments outcomes. All the findings
from this study will prove which parameters between cutting speed, feed rate and depth
of cut will give most effect to the surface roughness of mild steel using carbide cutting
tool especially in CNC turning machine.
1.2 Problem Statement
Currently in CNC turning operation, there are a few conditions of part after machining.
The conditions of the part are recognized by referring the accuracy of the dimension and
surface roughness. The good surface roughness is caused by many variables. It might be
cutting speed, feed rate or depth of cut. Hence, it is important to know suitable feed rate,
cutting speed and depth of cut in order to get fine surface roughness. For this project, the
main effects of machining parameters that will be analyze are feed rate, cutting speed
and depth of cut while machining process towards surface roughness. After machining
process, the surface roughness shall gives results depending on several of feed rate,
cutting speed and depth of cut used. Type of material used was mild steel and in order to
investigate the effect of those variables, an analysis will be carry out with help of the
previous study on the literature review on investigations into the effect of cutting
parameters on surface roughness in CNC turning machine.
7
1.3 Objective of Project
The purposes of this project are:
1. To analyze the effects of feed rate, cutting speed and depth of cut on machining
mild steel using carbide cutting tools.
2. To determine CNC Lathe Turning optimum parameters setting for machining
mild steel by utilization of Taguchi Method.
1.4 Scope of Project
This research investigate and analyze the relationship between surface roughness and
machining parameter like feed rate, cutting speed and depth of cut in turning operation.
Carbide cutting tool and mild steel will be use throughout this experiment. During this
machining process, the machining parameters are set to 3 different values. Taguchi
method was used as a tool to analyze and give the number of parameter that was run in
this study. However, there are few things that will not be taken in consideration such as
the cycle time which is the time taken in order to finish a product, the type of coolant
that will be use in the experiment and the capability of the carbide cutting tool to
produce the product. It is important to note that the mathematical modeling for this
study will not provided and it was out of the scope. The experiment will be done using
HAAS CNC turning machine. Each samples then planned to be analyzed using Surface
Roughness Tester, SJ-301 at the UTeM Metrology Lab.
8
1.5 Report Outline
This report writing consists of six chapters. Chapters 1 describes about the introduction,
which are include the background, problem statement, objectives, scope, and importance
of the study. In the other hand, chapter 2 stressed on the literature review of related
issues and chapter 3 highlighted more towards the methodology of the project, which is
include the process planning, flowchart, data gathering method and analytical technique
in the project. Chapter 4 is result analysis for experiment that will be done, while chapter
5 is consist discussion by refer to the result. Lastly, chapter 6 states the conclusion and
recommendations to improve the experiment for next time.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Legend Indicator Planning Actual
14 Complete the report and submit to supervisor
15 Preparation for oral presentation
16 Presentation PSM 1
First draft submission
8
9
Make flow chart for methodology
5
Writing up: Introduction
6
Writing up: Literature Review7
Meet and discuss the progress of PSM with supervisor
2 Making planning progress by Gantt Chart
3 Discuss the objectives and scopes with supervisor
4
Find all informations, journal and references book
Gantt Chart PSM 1
No. Task Week
1 Confirm project title and supervisor
1.6 Gantt Chart
Table 1.1: Gantt Chart for PSM 1