A Study On Hard Turning Process Of Ti-6AI-4V.
DECLARATION
I hereby, declared this report entitled “PSM Title” is the results of my own research
except as cited in references.
Signature
: ………………………………………….
Author’s Name
:
Nur Fadila Bte Rasdi.
Date
:
…………………………………………
6
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
Process (Process Manufacturing) with Honours. The member of the supervisory
committee is as follow:
(Signature of Supervisor)
………………………………
(Official Stamp of Supervisor)
7
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
Process (Process Manufacturing) with Honours. The member of the supervisory
committee is as follow:
(Signature of Principal Supervisor)
………………………………
(Official Stamp of Principal Supervisor)
(Signature of Co-Supervisor)
………………………………
(Official Stamp of Co-Supervisor)
8
ABSTRACT
In machining of parts, surface quality is one of the most specified customer
requirements. Major indication of surface quality on machined parts is surface
roughness. Therefore, this study on hard turning process of Ti-6Al-4V aims to
investigate the surface roughness mechanism of the hard turning process, determine any
significant of parameters that affect the surface roughness mechanism and utilize
statistical tool for the analysis of the surface roughness mechanism. This study mainly
focused in the investigation on cutting parameter which are feed rate, depth of cut,
cutting speed using coated and uncoated cutting tool type. The experimental utilizes the
Design of Experiment (DOE) as the approach to develop and analyze the whole study.
By utilizing Okuma LCS-15 CNC Lathe machine, 24 numbers of runs was carried out
and measured by using Surftest SJ-301. The result shown that for uncoated tools, feed
rate was the main parameter that effected to surface roughness while for the uncoated
tools the surface roughness most sensitive to cutting speed.
9
ABSTRAK
Di dalam pemesinan sesuatu bahagian, kualiti permukaan adalah spesifikasi penting di
dalam kehendak pengguna. Indikasi major pada kualiti permukaan adalah kekasaran
permukaan. Oleh itu, kajian terhadap pemesinan larik ke atas bahan kerja keluli keras
(AISI D2) bertujuan untuk menyiasat mekanisma kekasaran permukaan pada proses
melarik, menyatakan sebarang signifikasi parameter yang
member kesan pada
mekanisma kekasaran permukaan dan menggunakan alatan statistik untuk menganalisa
mekanisma kekasaran permukaan. Kajian ini memfokuskan penyiasatan ke atas
parameter pemotongan iaitu seperti kadar suapan pemesinan, kadar kedalaman
pemotongan, kelajuan pemotongan mengunakan mata alat pemotongan yang bersalut
dan tidak bersalut. Kajian experimental ini menggunakan pendekatan Design of
Experiment (DOE) untuk membangunkan serta menganalisa keseluruhan kajian. Mesin
larik Okuma LCS-15 CNC telah dipilih untuk menjalankan operasi pemesinan ke atas
benda kerja dan kadar kekasaran permukaan akan diukur dengan menggunakan Suftest
SJ-301. Keputusan menunjukkan bagi mata alat bersalut, kadar suapan pemesinan
member kesan pada kekasaran permukaan manakala untuk mata alat tidak bersalut,
kekasaran permukaan lebih sensitif terhadap kelajuan pemotongan.
10
DEDICATION
For a warmth of love to Abah and Emak, Siblings, friends and my love one.
Thank you for the undivided loves and supports.
11
ACKNOWLEDGEMENTS
First and foremost, a very thankful to Allah for His mercy, author could finally finish
PSM stage 1sucessfully, after experience a lot of obstacles and challenges. Special
thanks to Universiti Teknikal Malaysia Melaka for providing an opportunity to every
undergraduate student to experience and enhance skills at a specific project and thesis.
From this precious moment, a lot of things could be learned by students to prepare
themselves to face the global job world once they have graduated. Author cannot fully
express to Dr. Bagas Wordono, as the project supervisor for his valuable guides,
continuing support, sacrificing his personal time and for truly understanding whenever
obstacles happen throughout the entire PSM session. For without his guides and wisdom
this PSM report would be ruined. Not forgotten to thank all ADTEC Melaka especially
Mr Hisyam Bin Hashim and FKP lecturers who had spent their time to teach, explain
and answers all the questions. Last but not list, author also would like to address very
enormous appreciation to her family members and to her friends for their enthusiastic
support in finance, moral, guidance and all their contributions in order for author to
finish this PSM report successfully
12
TABLE OF CONTENT
Declaration
Aproval
Aproval
Abstract
i
Abstrak
ii
Dedication
iii
Acknowledgement
iv
Table of Content
v
List of Table
ix
List of Figure
x
List of Abbreviations
xiii
1.0 INTRODUCTION
1
1.1 Background of Study
1
1.2 Problem Statement
3
1.3 Objective
4
1.4 Scope
5
1.5 The Thesis Outline
5
13
2.0
LITERATURE REVIEW
6
2.1
Hard Turning Process
6
2.1.1
CNC Turning Machines
8
2.2
Surface Roughness
10
2.2.1
Surface Roughness Evaluation
11
2.2.2
Roughness Parameters
12
2.2.3
Profile Roughness Parameters
12
2.2.4
Amplitud Parameters
13
2.3.1
Material
14
2.4
Cutting Tools
16
2.4.1
Coated Tools
17
2.4.1.1 Coating Characteristic
17
2.4.2
Common Coating
18
2.4.3
Uncoated Tools
18
2.5
Design of Experiments
19
2.5.1
Key Terminology in Experimental Design
20
2.5.1.1 Set Good Objectives
20
2.5.1.2 Measure Response Quantitatively
21
2.5.1.3 Randomize the Run Order
23
2.5.1.4 Black out Known Sources of variation
23
2.5.1.5 Know Which Effect Will Be Discard
23
2.5.1.6 Do A Sequential Sources of Experiments
23
14
2.5.1.7 Confirm Critical Findings
23
2.5.2
Experimental Design Setup
23
2.5.3
Experimental Method Roadmap (Full Factorial DOE)
25
2.6
Cutting Parameter
25
2.6.1
Feed Rate
26
2.6.2
Cutting Speed
26
2.6.3
Depth of Cut
27
2.7
Previous Journal Review
28
3.0
METHODOLOGY
34
3.1
The DOE Approach
34
3.2
Research Variable
35
3.2.1
Machine Parameters
36
3.2.1.1 Minitab Software
36
3.2.1.2 Analyzing the DOE
38
3.3
Response Variable
39
3.3.1
Surface Roughness Measurement
39
3.4
Experimental Procedure
40
3.5
Experimental Material
40
3.6
Experimental Apparatus
41
3.6.1 CNC Lathe Machine
41
15
3.6.2 Surftest SJ-301
43
3.6.2.1 Procedures
44
3.6.4
XRD Machine
46
3.7
Data Collection
49
3.8
Process Flow Chart
50
4.0
RESULT AND ANALYSIS
51
4.1
Introduction
51
4.2
Surface roughness Analysis
52
4.3
Surface roughness quality
55
4.4
Result and analysis of surface roughness by DOE
57
4.4.1 Coated cutting tools
57
4.4.2 Uncoated cutting tools
66
4.5
Coating Analysis by using XRD Test
73
4.6
Problem Encountered
76
4.6.1
The workpiece (Titanium Alloy) consideration
76
4.6.2 Machine consideration
77
4.6.3 Chipping oriented
78
4.6.4 Chucking mechanism
79
4.6.5 Surface roughness measurement
79
4.6.6 Parameter setting
80
16
5.0
CONCLUSION AND RECOMMENDATION
82
5.1
Conclusion
82
5.2
Recommendation
84
REFERENCES
85
APENDIX
17
LIST OF TABLES
2.1
Nominal chemical composition of Ti-6Al-4V alloy (%)
14
2.2
The mechanical properties of Titanium Alloy
15
2.3
Typical Chemical Analysis
16
2.5
Previous Journal Review
28
3.1
Machining Parameters Used in Experiment and Their Levels
35
3.2
The Orthogonal Arrays for the Experiment
37
3.3
The Okuma LCS-15 CNC Lathe Specification
42
3.4
The Specific Data of Surftest SJ-301
43
3.5
The cutting tools
44
3.6
The process planning for coated cutting tools
45
3.7
The process planning for uncoated cutting tools
48
4.1
Experimental data for surface roughness for coated cutting tool.
52
4.2
Experimental data for surface roughness for uncoated cutting tool
53
4.3
The quality evaluation of Titanium Alloy
55
4.4
The evaluation of surface roughness quality
56
4.5
Main effect plot for surface roughness
62
4.6
Estimated effects and coefficients for surface roughness, Ra
63
4.7
The factors and value to obtain R-squared
64
18
4.8
Analysis of Variance (ANOVA)
64
4.9
R-squared- Relative Significance for coated cutting tools
65
4.10
Main effect plot for surface roughness
70
4.11
Estimated effects and coefficients for surface roughness, Ra
71
4.12
The factors and value to obtain R-squared
72
4.13
Analysis of Variance (ANOVA)
72
4.14
R-squared- Relative Significance for uncoated cutting tools
72
19
LIST OF FIGURES
2.1
The Conventional Turning Machine
7
2.2
The CNC Lathe Machine
8
2.3
The Surface Roughness Parameters
10
2.4
The Depth of Cut
28
3.1
Steps in Minitab Software
36
3.2
Titanium Alloy
40
3.3
The Okuma LCS-15 CNC Lathe
41
3.4
The Surftest SJ-301
42
3.5
The calibration operation.
43
3.6
The X-PERT XRD Machine
45
3.8
The process flow chart
50
4.1
The plotted graph of surface roughness versus run order
53
(Coated cutting tools)
4.2
The plotted graph of surface roughness versus run order
54
(Uncoated cutting tools)
4.3
Residual plot for average surface roughness
57
4.4
The normal plot of standardized effects on the surface roughness
59
4.5
Pareto chart of the standardized effects for the surface roughness
60
4.6
Main effect plotted graph for the surface roughness
61
20
4.7
Interaction plot between the parameters and surface roughness
62
4.8
Residual plot of ANOVA
65
4.9
Residual plot for Average Surface Roughness, Ra.
66
4.10
The normal plot of standardized effects on the surface roughness
67
4.11
Pareto chart of the standardized effects for the surface roughness
69
4.12
Main effect plotted graph for the surface roughness
69
4.13
Interaction plot between the parameters and surface roughness
70
4.14
Residual plot of ANOVA
73
4.15
The average chemical composition in the coated tools.
74
4.16
The intensity versus angle
74
4.17
The cutting operation by using Horizontal Band Saw machine
75
4.18
The facing and drilling operation
76
4.19
The supported workpiece with tail stock
78
4.20
The chip produced during the machining of Titanium Alloy
78
4.21
The surface roughness measurement method.
79
21
LIST OF ABBREVIATIONS
%
Percentage
0
Degree Celcius
C
AISI
The American Iron and Steel Institution.
ANOVA
Analysis of Variance
CAD
Computer Aided Drawing
CAM
Computer Aided Machine
CLA
Centre Line Average
CNC
Computer Numerical Control
Cr
Chromium
CVD
Chemical Vapor Deposition
DOC
Depth of Cut
DOE
Design of Experiment
F
Farenheit
f
Feed rate
HB
Brinalls Hardness Number
HRC
Rockwell Hardness Number
ISO
International Standard Organization
Ipr
inches per minutes
Mn
Manganese
22
mm
millimeter
PCBN
PolyCarbon Boron Nitride
PVD
Physical Vapor Deposition
Ra
Roughness Average
rev
revolution
SEM
Scanning Electron Microscope.
v
cutting speed
XRD
X-Ray diffraction
23
CHAPTER 1
INTRODUCTION
This study is mainly on the experimental test of the hard turning process on the Titanium
Alloy Steel which mainly focuses on the surface quality of the steel. This study on the
surface quality will investigate the three main parameters which including the cutting
speed, feed rate and the depth of cut using coated and uncoated cutting tools. Thus, this
study and investigation will assess the characteristics in high-precision of high hardened components.
1.1 Background of study.
Most machining operations can be divided into those that remove metal from an item,
and those that form metal in an item. Often an unfinished workpiece will need to have
some parts removed or scraped away in order to create a finished product. For example,
a lathe is a machine tool that generates circular sections by rotating a metal workpiece,
so that a cutting tool can peel metal off, creating a smooth, round surface. A drill or
punch press can be used to remove metal in the shape of a hole. Other tools that may be
used for various types of metal removal are milling machines, saws, and grinding tools.
Many of these same techniques are used in woodworking.
Metal can be formed into a desired shape much more easily than materials such as wood
or stone, especially when the metal is heated. A machinist may use a forging machine to
hammer or mold a hot metal workpiece into a desired shape. Dies or molds may be used
if the metal is soft enough, or under high pressures. A press is used to flatten a piece of
metal into a desired shape. Advanced machining operations might use electrical
24
discharge, electro-chemical erosion, or laser cutting to shape metal workpieces.
As a commercial venture, machining is generally performed in a machine shop, which
consists of one or more workrooms containing major machine tools. Although a machine
shop can be a standalone operation, many businesses maintain internal machine shops
which support specialized needs of the business. The inferior finish found on the
machined surface of a workpiece may be caused by insufficient clamping, cutting
conditions or perhaps an incorrectly adjusted machine. It is evident by an undulating or
irregular finish, and the appearance of waves on the surface.
As quoted from Kaewkuekool, S. et al. (2007), the three principal machining processes
are classified as turning, drilling and milling. Other operations falling into miscellaneous
categories include shaping, planning, boring, broaching and sawing. Turning operations
are operations that rotate the workpiece as the primary method of moving metal against
the cutting tool. Lathes are the principal machine tool used in turning. Milling operations
are operations in which the cutting tool rotates to bring cutting edges to bear against the
workpiece. Milling machines are the principal machine tool used in milling. Drilling
operations are operations in which holes are produced or refined by bringing a rotating
cutter with cutting edges at the lower extremity into contact with the workpiece. Drilling
operations are done primarily in drill presses but not uncommonly on lathes or mills.
Miscellaneous operations are operations that strictly speaking may not be machining
operations in that they may not be chip producing operations but these operations are
performed at a typical machine tool. Burnishing is an example of a miscellaneous
operation. Burnishing produces no chips but can be performed at a lathe, mill, or drill
press.
An unfinished workpiece requiring machining will need to have some material cut away
to create a finished product. A finished product would be a workpiece that meets the
specifications set out for that workpiece by engineering drawings or blueprints. For
example, a workpiece may be required to have a specific outside diameter. A lathe is a
machine tool that can be used to create that diameter by rotating a metal workpiece, so
that a cutting tool can cut metal away, creating a smooth, round surface matching the
25
required diameter and surface finish. A drill can be used to remove metal in the shape of
a cylindrical hole. Other tools that may be used for various types of metal removal are
milling machines, saws, and grinding tools. Many of these same techniques are used in
woodworking.
Machining requires attention to many details for a workpiece to meet the specifications
set out in the engineering drawings or blueprints. Besides the obvious problems related
to correct dimensions, there is the problem of achieving the correct finish or surface
smoothness on the workpiece. The inferior finish found on the machined surface of a
workpiece may be caused by incorrect clamping, dull tool, or inappropriate presentation
of a tool. Frequently, this poor surface finish, known as chatter, is evident by an
undulating or irregular finish, and the appearance of waves on the machined surfaces of
the workpiece.
1.2 Problem Statement.
The challenge of modern machining industries is mainly focused on the achievement of
high quality, in terms of workpiece dimensional accuracy, surface finish, high
production rate, less wear on the cutting tools, economy of machining in terms of cost
saving and increase the performance of the product with reduced environmental impact.
Surface roughness plays an important role in many areas and is a factor of great
importance in the evaluation of machining accuracy. Many researchers developed many
mathematical models to optimize the cutting parameters to get lowest surface roughness
by turning process. The variation in the material hardness, alloying elements present in
the work piece material and other factors affecting surface finish and tool wear. This
experimental study will investigate
the influence of surface roughness by cutting
parameters such as cutting speed, feed rate, depth of cut and the cutting tool types in
order to obtain the best parameters to better finish of surface roughness. Thamizhmanii,
S. et al. (2006)
Turning is very important machining process in which a single point cutting tool
removes unwanted material from the surface of a rotating cylindrical work piece. The
cutting tool is fed linearly in a direction parallel to the axis of rotation. Turning is carried
26
on a lathe that provides the power to turn the work piece at a given rotational speed and
to feed to the cutting tool at specified rate and depth of cut. Therefore three cutting
parameters namely as cutting speed, feed rate, depth of cut utilizing the coated and
uncoated type of cutting tools need to be determined in a turning operation.
In a typical turning operation, the workpiece is clamped by any one of the workholding
devices. Long and slender parts must be supported by a steady rest and follow rest
placed on the bed, as otherwise the parts deflect under the cutting forces. These rests
usually equipped with three adjustable fingers or rollers that support the workpiece
while allowing it to rotate freely. Examples of objects that can be produced on a lathe
include candlestick holders, cue sticks, table legs, bowls, baseball bats, musical
instruments, crankshafts and camshafts.
The turning operations are accomplished using a cutting tool; the high forces and
temperature during machining create a harsh environment for the cutting tool. Therefore
tool life is important to evaluate cutting performance. The purpose of turning operation
is to produce low surface roughness of the parts.
Surface roughness is another important factor to evaluate cutting performance. Proper
selection of cutting parameters and tool can produce longer tool life and lower surface
roughness. Hence, design of experiments (DOE) on cutting parameters was adopted to
study the surface roughness. Surface properties such as roughness are critical to the
function ability of machine components. Increased understanding of the surface
generation mechanisms can be used to optimize machining process and to improve
component functionability.
1.3 Objective
In particular, the objectives of this study can be described as following:
To investigate the surface roughness quality of the hard turning process.
27
I hereby, declared this report entitled “PSM Title” is the results of my own research
except as cited in references.
Signature
: ………………………………………….
Author’s Name
:
Nur Fadila Bte Rasdi.
Date
:
…………………………………………
6
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
Process (Process Manufacturing) with Honours. The member of the supervisory
committee is as follow:
(Signature of Supervisor)
………………………………
(Official Stamp of Supervisor)
7
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
Process (Process Manufacturing) with Honours. The member of the supervisory
committee is as follow:
(Signature of Principal Supervisor)
………………………………
(Official Stamp of Principal Supervisor)
(Signature of Co-Supervisor)
………………………………
(Official Stamp of Co-Supervisor)
8
ABSTRACT
In machining of parts, surface quality is one of the most specified customer
requirements. Major indication of surface quality on machined parts is surface
roughness. Therefore, this study on hard turning process of Ti-6Al-4V aims to
investigate the surface roughness mechanism of the hard turning process, determine any
significant of parameters that affect the surface roughness mechanism and utilize
statistical tool for the analysis of the surface roughness mechanism. This study mainly
focused in the investigation on cutting parameter which are feed rate, depth of cut,
cutting speed using coated and uncoated cutting tool type. The experimental utilizes the
Design of Experiment (DOE) as the approach to develop and analyze the whole study.
By utilizing Okuma LCS-15 CNC Lathe machine, 24 numbers of runs was carried out
and measured by using Surftest SJ-301. The result shown that for uncoated tools, feed
rate was the main parameter that effected to surface roughness while for the uncoated
tools the surface roughness most sensitive to cutting speed.
9
ABSTRAK
Di dalam pemesinan sesuatu bahagian, kualiti permukaan adalah spesifikasi penting di
dalam kehendak pengguna. Indikasi major pada kualiti permukaan adalah kekasaran
permukaan. Oleh itu, kajian terhadap pemesinan larik ke atas bahan kerja keluli keras
(AISI D2) bertujuan untuk menyiasat mekanisma kekasaran permukaan pada proses
melarik, menyatakan sebarang signifikasi parameter yang
member kesan pada
mekanisma kekasaran permukaan dan menggunakan alatan statistik untuk menganalisa
mekanisma kekasaran permukaan. Kajian ini memfokuskan penyiasatan ke atas
parameter pemotongan iaitu seperti kadar suapan pemesinan, kadar kedalaman
pemotongan, kelajuan pemotongan mengunakan mata alat pemotongan yang bersalut
dan tidak bersalut. Kajian experimental ini menggunakan pendekatan Design of
Experiment (DOE) untuk membangunkan serta menganalisa keseluruhan kajian. Mesin
larik Okuma LCS-15 CNC telah dipilih untuk menjalankan operasi pemesinan ke atas
benda kerja dan kadar kekasaran permukaan akan diukur dengan menggunakan Suftest
SJ-301. Keputusan menunjukkan bagi mata alat bersalut, kadar suapan pemesinan
member kesan pada kekasaran permukaan manakala untuk mata alat tidak bersalut,
kekasaran permukaan lebih sensitif terhadap kelajuan pemotongan.
10
DEDICATION
For a warmth of love to Abah and Emak, Siblings, friends and my love one.
Thank you for the undivided loves and supports.
11
ACKNOWLEDGEMENTS
First and foremost, a very thankful to Allah for His mercy, author could finally finish
PSM stage 1sucessfully, after experience a lot of obstacles and challenges. Special
thanks to Universiti Teknikal Malaysia Melaka for providing an opportunity to every
undergraduate student to experience and enhance skills at a specific project and thesis.
From this precious moment, a lot of things could be learned by students to prepare
themselves to face the global job world once they have graduated. Author cannot fully
express to Dr. Bagas Wordono, as the project supervisor for his valuable guides,
continuing support, sacrificing his personal time and for truly understanding whenever
obstacles happen throughout the entire PSM session. For without his guides and wisdom
this PSM report would be ruined. Not forgotten to thank all ADTEC Melaka especially
Mr Hisyam Bin Hashim and FKP lecturers who had spent their time to teach, explain
and answers all the questions. Last but not list, author also would like to address very
enormous appreciation to her family members and to her friends for their enthusiastic
support in finance, moral, guidance and all their contributions in order for author to
finish this PSM report successfully
12
TABLE OF CONTENT
Declaration
Aproval
Aproval
Abstract
i
Abstrak
ii
Dedication
iii
Acknowledgement
iv
Table of Content
v
List of Table
ix
List of Figure
x
List of Abbreviations
xiii
1.0 INTRODUCTION
1
1.1 Background of Study
1
1.2 Problem Statement
3
1.3 Objective
4
1.4 Scope
5
1.5 The Thesis Outline
5
13
2.0
LITERATURE REVIEW
6
2.1
Hard Turning Process
6
2.1.1
CNC Turning Machines
8
2.2
Surface Roughness
10
2.2.1
Surface Roughness Evaluation
11
2.2.2
Roughness Parameters
12
2.2.3
Profile Roughness Parameters
12
2.2.4
Amplitud Parameters
13
2.3.1
Material
14
2.4
Cutting Tools
16
2.4.1
Coated Tools
17
2.4.1.1 Coating Characteristic
17
2.4.2
Common Coating
18
2.4.3
Uncoated Tools
18
2.5
Design of Experiments
19
2.5.1
Key Terminology in Experimental Design
20
2.5.1.1 Set Good Objectives
20
2.5.1.2 Measure Response Quantitatively
21
2.5.1.3 Randomize the Run Order
23
2.5.1.4 Black out Known Sources of variation
23
2.5.1.5 Know Which Effect Will Be Discard
23
2.5.1.6 Do A Sequential Sources of Experiments
23
14
2.5.1.7 Confirm Critical Findings
23
2.5.2
Experimental Design Setup
23
2.5.3
Experimental Method Roadmap (Full Factorial DOE)
25
2.6
Cutting Parameter
25
2.6.1
Feed Rate
26
2.6.2
Cutting Speed
26
2.6.3
Depth of Cut
27
2.7
Previous Journal Review
28
3.0
METHODOLOGY
34
3.1
The DOE Approach
34
3.2
Research Variable
35
3.2.1
Machine Parameters
36
3.2.1.1 Minitab Software
36
3.2.1.2 Analyzing the DOE
38
3.3
Response Variable
39
3.3.1
Surface Roughness Measurement
39
3.4
Experimental Procedure
40
3.5
Experimental Material
40
3.6
Experimental Apparatus
41
3.6.1 CNC Lathe Machine
41
15
3.6.2 Surftest SJ-301
43
3.6.2.1 Procedures
44
3.6.4
XRD Machine
46
3.7
Data Collection
49
3.8
Process Flow Chart
50
4.0
RESULT AND ANALYSIS
51
4.1
Introduction
51
4.2
Surface roughness Analysis
52
4.3
Surface roughness quality
55
4.4
Result and analysis of surface roughness by DOE
57
4.4.1 Coated cutting tools
57
4.4.2 Uncoated cutting tools
66
4.5
Coating Analysis by using XRD Test
73
4.6
Problem Encountered
76
4.6.1
The workpiece (Titanium Alloy) consideration
76
4.6.2 Machine consideration
77
4.6.3 Chipping oriented
78
4.6.4 Chucking mechanism
79
4.6.5 Surface roughness measurement
79
4.6.6 Parameter setting
80
16
5.0
CONCLUSION AND RECOMMENDATION
82
5.1
Conclusion
82
5.2
Recommendation
84
REFERENCES
85
APENDIX
17
LIST OF TABLES
2.1
Nominal chemical composition of Ti-6Al-4V alloy (%)
14
2.2
The mechanical properties of Titanium Alloy
15
2.3
Typical Chemical Analysis
16
2.5
Previous Journal Review
28
3.1
Machining Parameters Used in Experiment and Their Levels
35
3.2
The Orthogonal Arrays for the Experiment
37
3.3
The Okuma LCS-15 CNC Lathe Specification
42
3.4
The Specific Data of Surftest SJ-301
43
3.5
The cutting tools
44
3.6
The process planning for coated cutting tools
45
3.7
The process planning for uncoated cutting tools
48
4.1
Experimental data for surface roughness for coated cutting tool.
52
4.2
Experimental data for surface roughness for uncoated cutting tool
53
4.3
The quality evaluation of Titanium Alloy
55
4.4
The evaluation of surface roughness quality
56
4.5
Main effect plot for surface roughness
62
4.6
Estimated effects and coefficients for surface roughness, Ra
63
4.7
The factors and value to obtain R-squared
64
18
4.8
Analysis of Variance (ANOVA)
64
4.9
R-squared- Relative Significance for coated cutting tools
65
4.10
Main effect plot for surface roughness
70
4.11
Estimated effects and coefficients for surface roughness, Ra
71
4.12
The factors and value to obtain R-squared
72
4.13
Analysis of Variance (ANOVA)
72
4.14
R-squared- Relative Significance for uncoated cutting tools
72
19
LIST OF FIGURES
2.1
The Conventional Turning Machine
7
2.2
The CNC Lathe Machine
8
2.3
The Surface Roughness Parameters
10
2.4
The Depth of Cut
28
3.1
Steps in Minitab Software
36
3.2
Titanium Alloy
40
3.3
The Okuma LCS-15 CNC Lathe
41
3.4
The Surftest SJ-301
42
3.5
The calibration operation.
43
3.6
The X-PERT XRD Machine
45
3.8
The process flow chart
50
4.1
The plotted graph of surface roughness versus run order
53
(Coated cutting tools)
4.2
The plotted graph of surface roughness versus run order
54
(Uncoated cutting tools)
4.3
Residual plot for average surface roughness
57
4.4
The normal plot of standardized effects on the surface roughness
59
4.5
Pareto chart of the standardized effects for the surface roughness
60
4.6
Main effect plotted graph for the surface roughness
61
20
4.7
Interaction plot between the parameters and surface roughness
62
4.8
Residual plot of ANOVA
65
4.9
Residual plot for Average Surface Roughness, Ra.
66
4.10
The normal plot of standardized effects on the surface roughness
67
4.11
Pareto chart of the standardized effects for the surface roughness
69
4.12
Main effect plotted graph for the surface roughness
69
4.13
Interaction plot between the parameters and surface roughness
70
4.14
Residual plot of ANOVA
73
4.15
The average chemical composition in the coated tools.
74
4.16
The intensity versus angle
74
4.17
The cutting operation by using Horizontal Band Saw machine
75
4.18
The facing and drilling operation
76
4.19
The supported workpiece with tail stock
78
4.20
The chip produced during the machining of Titanium Alloy
78
4.21
The surface roughness measurement method.
79
21
LIST OF ABBREVIATIONS
%
Percentage
0
Degree Celcius
C
AISI
The American Iron and Steel Institution.
ANOVA
Analysis of Variance
CAD
Computer Aided Drawing
CAM
Computer Aided Machine
CLA
Centre Line Average
CNC
Computer Numerical Control
Cr
Chromium
CVD
Chemical Vapor Deposition
DOC
Depth of Cut
DOE
Design of Experiment
F
Farenheit
f
Feed rate
HB
Brinalls Hardness Number
HRC
Rockwell Hardness Number
ISO
International Standard Organization
Ipr
inches per minutes
Mn
Manganese
22
mm
millimeter
PCBN
PolyCarbon Boron Nitride
PVD
Physical Vapor Deposition
Ra
Roughness Average
rev
revolution
SEM
Scanning Electron Microscope.
v
cutting speed
XRD
X-Ray diffraction
23
CHAPTER 1
INTRODUCTION
This study is mainly on the experimental test of the hard turning process on the Titanium
Alloy Steel which mainly focuses on the surface quality of the steel. This study on the
surface quality will investigate the three main parameters which including the cutting
speed, feed rate and the depth of cut using coated and uncoated cutting tools. Thus, this
study and investigation will assess the characteristics in high-precision of high hardened components.
1.1 Background of study.
Most machining operations can be divided into those that remove metal from an item,
and those that form metal in an item. Often an unfinished workpiece will need to have
some parts removed or scraped away in order to create a finished product. For example,
a lathe is a machine tool that generates circular sections by rotating a metal workpiece,
so that a cutting tool can peel metal off, creating a smooth, round surface. A drill or
punch press can be used to remove metal in the shape of a hole. Other tools that may be
used for various types of metal removal are milling machines, saws, and grinding tools.
Many of these same techniques are used in woodworking.
Metal can be formed into a desired shape much more easily than materials such as wood
or stone, especially when the metal is heated. A machinist may use a forging machine to
hammer or mold a hot metal workpiece into a desired shape. Dies or molds may be used
if the metal is soft enough, or under high pressures. A press is used to flatten a piece of
metal into a desired shape. Advanced machining operations might use electrical
24
discharge, electro-chemical erosion, or laser cutting to shape metal workpieces.
As a commercial venture, machining is generally performed in a machine shop, which
consists of one or more workrooms containing major machine tools. Although a machine
shop can be a standalone operation, many businesses maintain internal machine shops
which support specialized needs of the business. The inferior finish found on the
machined surface of a workpiece may be caused by insufficient clamping, cutting
conditions or perhaps an incorrectly adjusted machine. It is evident by an undulating or
irregular finish, and the appearance of waves on the surface.
As quoted from Kaewkuekool, S. et al. (2007), the three principal machining processes
are classified as turning, drilling and milling. Other operations falling into miscellaneous
categories include shaping, planning, boring, broaching and sawing. Turning operations
are operations that rotate the workpiece as the primary method of moving metal against
the cutting tool. Lathes are the principal machine tool used in turning. Milling operations
are operations in which the cutting tool rotates to bring cutting edges to bear against the
workpiece. Milling machines are the principal machine tool used in milling. Drilling
operations are operations in which holes are produced or refined by bringing a rotating
cutter with cutting edges at the lower extremity into contact with the workpiece. Drilling
operations are done primarily in drill presses but not uncommonly on lathes or mills.
Miscellaneous operations are operations that strictly speaking may not be machining
operations in that they may not be chip producing operations but these operations are
performed at a typical machine tool. Burnishing is an example of a miscellaneous
operation. Burnishing produces no chips but can be performed at a lathe, mill, or drill
press.
An unfinished workpiece requiring machining will need to have some material cut away
to create a finished product. A finished product would be a workpiece that meets the
specifications set out for that workpiece by engineering drawings or blueprints. For
example, a workpiece may be required to have a specific outside diameter. A lathe is a
machine tool that can be used to create that diameter by rotating a metal workpiece, so
that a cutting tool can cut metal away, creating a smooth, round surface matching the
25
required diameter and surface finish. A drill can be used to remove metal in the shape of
a cylindrical hole. Other tools that may be used for various types of metal removal are
milling machines, saws, and grinding tools. Many of these same techniques are used in
woodworking.
Machining requires attention to many details for a workpiece to meet the specifications
set out in the engineering drawings or blueprints. Besides the obvious problems related
to correct dimensions, there is the problem of achieving the correct finish or surface
smoothness on the workpiece. The inferior finish found on the machined surface of a
workpiece may be caused by incorrect clamping, dull tool, or inappropriate presentation
of a tool. Frequently, this poor surface finish, known as chatter, is evident by an
undulating or irregular finish, and the appearance of waves on the machined surfaces of
the workpiece.
1.2 Problem Statement.
The challenge of modern machining industries is mainly focused on the achievement of
high quality, in terms of workpiece dimensional accuracy, surface finish, high
production rate, less wear on the cutting tools, economy of machining in terms of cost
saving and increase the performance of the product with reduced environmental impact.
Surface roughness plays an important role in many areas and is a factor of great
importance in the evaluation of machining accuracy. Many researchers developed many
mathematical models to optimize the cutting parameters to get lowest surface roughness
by turning process. The variation in the material hardness, alloying elements present in
the work piece material and other factors affecting surface finish and tool wear. This
experimental study will investigate
the influence of surface roughness by cutting
parameters such as cutting speed, feed rate, depth of cut and the cutting tool types in
order to obtain the best parameters to better finish of surface roughness. Thamizhmanii,
S. et al. (2006)
Turning is very important machining process in which a single point cutting tool
removes unwanted material from the surface of a rotating cylindrical work piece. The
cutting tool is fed linearly in a direction parallel to the axis of rotation. Turning is carried
26
on a lathe that provides the power to turn the work piece at a given rotational speed and
to feed to the cutting tool at specified rate and depth of cut. Therefore three cutting
parameters namely as cutting speed, feed rate, depth of cut utilizing the coated and
uncoated type of cutting tools need to be determined in a turning operation.
In a typical turning operation, the workpiece is clamped by any one of the workholding
devices. Long and slender parts must be supported by a steady rest and follow rest
placed on the bed, as otherwise the parts deflect under the cutting forces. These rests
usually equipped with three adjustable fingers or rollers that support the workpiece
while allowing it to rotate freely. Examples of objects that can be produced on a lathe
include candlestick holders, cue sticks, table legs, bowls, baseball bats, musical
instruments, crankshafts and camshafts.
The turning operations are accomplished using a cutting tool; the high forces and
temperature during machining create a harsh environment for the cutting tool. Therefore
tool life is important to evaluate cutting performance. The purpose of turning operation
is to produce low surface roughness of the parts.
Surface roughness is another important factor to evaluate cutting performance. Proper
selection of cutting parameters and tool can produce longer tool life and lower surface
roughness. Hence, design of experiments (DOE) on cutting parameters was adopted to
study the surface roughness. Surface properties such as roughness are critical to the
function ability of machine components. Increased understanding of the surface
generation mechanisms can be used to optimize machining process and to improve
component functionability.
1.3 Objective
In particular, the objectives of this study can be described as following:
To investigate the surface roughness quality of the hard turning process.
27