PERPUSTAKAAN UMP
DII ID ID ID ID I UD I IDU I DI
0000072819
SURFACE ROUGHNESS IN LATHE BORING OPERATION
ALISANDRA ARIEZA FOU BT MUHD FARID FOU
Report submitted in partial fulfilment of the requirements for the award of degree of Bachelor of Mechanical Engineering
Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG
JUNE 2012
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ABSTRACT
Optimizing the cutting parameters is important to obtain the best surface roughness, to minimize the cost of production and to increase productivity. The main objective of the project are to study the optimum cutting parameters that are the cutting speed, feed rate and depth of cut for single tool boring process to obtain the best surface roughness. The Brinell hardness of the material tested is 151. In this study, the Design of Experiment (DOE) with Box-Behnken design is used. By using the STATISTICA software a table of run was generated based on the full factorial with three factor and three levels. Twenty seven experiments are then run according to the "Table of run" generated by the STATISTICA software and the surface roughness value is recorded. Analysis of variance (ANOVA) was used to identify the significant cutting parameters that affect the surface roughness. The ANOVA table has shown that from the 27 experiments, cutting speeds and depth of cut are significant. From the experiment, rough optimization values are obtained. The rough optimizations of cutting speeds are 110 mlmin and the depths of cut are , 0.278 mm gives a surface roughness value of 2.18 pm. The experiments are continued by another ten experiments to find the fine optimized cutting speed and depth of cut to obtain the best surface roughness. It was concluded that the fine optimization cutting speeds for the mild steel (AISI 1019) are 112 m/min and the depths of cut are 0.182 mm gives a surface roughness of 2.06 pm for the specific machine. The usage of a harder material which is commonly used in industry and cutting parameter such as tool nose radius and length of the boring tool is highly recommended to find the optimization parameter for the best surface roughness in the boring operation.
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ABSTRAK
Mengoptimumkafl parameter pemotongan adalah penting untuk mendapatkan tahap kekasaran permukaan yang terbaik, mengurangkan kos pengeluaran clan meningkatkan produktiviti. Objektif utama projek mi adalah untuk mencari parameter optimum pemotongan, iaitu kelajuan pemotongan, kadar suapan dan kedalaman pemotongan bagi proses membuat lubang untuk mendapatkan kekasaran permukaan yang terbaik. Kekerasan Brinell untuk keluli yang digunakan ialah 151. Dalam kaj ian mi, RekabefltUk Eksperimen menggunakan reka bentuk Box-Behnken. Dengan menggunakan perisian STATISTICA, jadual jangka dibuat berdasarkan faktorial lengkap dengan tiga faktor dan tiga peringkat. Kemudian, 27 uji kaji dijalankan berdasarkafl "Jadual jangkaan" yang dihasilkan oleh perisian STATISTICA clan nilai kekasaran permukaan direkodkan. Analisis varians (ANOVA) telah digunakan untuk mengenalpasti parameter pemotongan yang penting yang memberi kesan kepada kekasaran permukaan. Jadual ANOVA telah menunjukkan bahawa daripada 27 eksperimen, kelajuan pemotongan dan kedalaman pemotongan telah memberi kesan kepada kekasaran pemotongan. Daripada eksperimen tersebut, nilai-nilai pengoptimuman peringkat pertama akan diperolehi. Pengoptimuman peringkat pertama untuk kelajuan pemotongan ialah 110 m / min dan kedalaman pemotongan ialah 0.278 mm akan memberikan nilai kekasaran permukaan sebanyak 2.18 tm. Eksperimen diteruskan dengan . sepuluh ujikaji lagi untuk mencari kelajuan pemotongan dan kedalaman pemotongan yang paling optimum untuk mendapatkan kekasaran permukaan yang terbaik. Eksperimen telah dilakukan untuk mendapatkan kelajuan optimum pemotongan dan kedalaman. Kesimpulannya, pengoptimuman kelajuan pemotongan untuk keluli (AISI 1019) ialah 112 m / min dan kedalaman pemotongan ialah 0.182 mm memberikan kekasaran permukaan sebanyak 2.06 pm. mi adalah untuk mesin yang tertentu sahaja. Penggunaan bahan yang lebih keras yang banyak digunakan di industri dan parameter pemotongan seperti jejari alat pemotong dan panjang pemotongan amat disyorkan untuk mencari parameter yang paling optimum bagi kekasaran permukaan yang terbaik dalam operasi membuat lubang.
TABLE OF CONTENTS Page EXAMINER DECLERATION 11 SUPERVISOR'S DECLARATION STUDENT'S DECLARATION iv DEDICATION ACKNOWLEDGEMENTS vi ABSTRACT ABSTRAK TABLE OF CONTENTS xi
LIST OF TABLES xii
LIST OF FIGURES xiv
LIST OF SYMBOLS xviii
LIST OF ABBREVIATIONS xix
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 the Project 3
1.6 Summary 4
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 5
2.2 Theory of Metal Cutting 6
2.2.1 Orthogonal cutting and Oblique cutting 8
2.2.2 Metal Cutting in Turning Operation 9
2.2.3 Tool Geometry 9
2.2.4 Cutting tool material 11
2.3 Lathe Machine 12
2.4 Cutting Parameter 13
2.5 Lathe Boring Process 16
2.6 Lathe Boring Cutting Parameter 17
2.7 Literature Review On Surface Roughness In Lathe Boring and 18 Turning. Operation
2.8 Material Used Based on Earlier . Researcher 24
2.9 Vibration in Boring Operation 27
2.10 Cutting Force In Lathe Boring Operation 27
2.11 Surface Roughness 28 2.12 Measuring Techniques 31 2.13 Stylus Instrument 31 2.14 Summary 32 CHAPTER 3 METHODOLOGY 3.1 Introduction 33
3.2 Methodology Flow Chart 33
3.3. Important of Study 37
3.4 Choice of Experiment Design 37
3.4.1 Lathe machine 37 3.4.2 Assumption made 37 3.4.3 Variable parameter 38 3.4.4 Fixed parameter 38 3.4.5 Cutting profile 39 3.4.6 Preliminary test 39 3.5 Design of Experiment 40
3.5.1 Randomization and blocking 40
3.5.2 Table of run 41 3.6 Performing Experiment 45 3.6.1 Identification of workpiece 45 3.6.2 Material Preparation 48 3.6.3 Experiment Procedure 49 3.6.4 Calculation of RPM 52 3.6.5 Precautions 52 3.7 Data Collection
3.7.1 Surface roughness measurement 53
3.8 Data Analysis
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Introduction 58
4.2 Impact of cutting parameters on the surface roughness 58
4.3 Statistical analysis 59
4.3.1 Statistical analysis for the 27 experiment 59 4.3.2 Statistical analysis for the 10 experiment 80
4.4 Discussion 93
4.5 Summary 95
CHAPTER 5 CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 96
5.2 Recommendation 97
REFERENCES 98
APPENDICES
Al Surface roughness for basic processes 102
A2 Mild Steel Composition Result 103
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LIST OF TABLES
Table No. Title Page
2.1 Level of Independent Variable 19
2.2 Factors, units, codes, and level used for the orthogonal array 20 L1 8(2^2x3^6)
2.3 Experiment level for conducting experiment 21
2.4 Experiment reading after machining the specimens as per 22 experiment level.
2.5 Cutting Parameters 23
2.6 Cutting parameters and their levels (cutting speed is kept constant 23 300 rn/mm)
2.7 Mechanical properties of AISI 1026 plain carbon steel 24
2.8 Chemical composition of AISI 1026 plain carbon steel, % weight 24
2.9 Mechanical properties of AISI 1018 carbon steel 25
2.10 Chemical composition of AISI 1018 carbon steel, % weight 25
2.11 Mechanical properties of Aluminum 6061 T6 25
2.12 Chemical composition of Aluminum 6061 T6, % weight 25
2.13 Mechanical properties of AISI 4140 steel 26
2.14 Chemical composition of AISI 4140 steel, % weight 26
2.15 Mechanical properties of AISI 1030 carbon steel 26
2.16 Chemical composition of AISI 1030 carbon steel, % weight 27
3.1 Variable parameter and experimental design level 38
3.2 Fixed parameter 38
3.3 Cutting speed, feed rate and depth of cut for preliminary test 40
3.4 Composition of mild steel 46
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3.6 RPM for drilling operation 52
RPM for boring operation 52
4.1 Ra values for each specimen (27 experiments) 59
4.2 Ra values for each specimen (10 experiments) 82
4.3 Cutting speed and depth of cut influent the surface roughness 94 4 •4 Comparison between Rough Optimization and Fine Optimization 95
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3.6 Summary of variable 44
3.7 Table of Runs 44
3.8 Spectrometer 45
3.9 Mild steel after being spark 46
3.10 Roll Grinder 47
3.11 Brinell Hardness Tester 48
3.12 Three diameter after the Brinell Hardness Test 48
3.13 Lathe Machine 50
3.14 Tools used during boring process 50
3.15 Cutting tool, (a) drill, (b) center drill, (c) boring bar, and (d) single 51 point cutting tool
3.16 Boring operation 51
3.17 After boring process 51
3.18 Perthometer S2 set 53
3.19 The four place to measure of Ra value 54
3.20 Dependent and independent variable selection in "STATISTICA" 55
3.21 Model selection 56
3.22 ANOVA selections 56
4.1 Ra value filled in "Table of Run" 60
4.2 Analyzed design selection 61
4.3 Variable selection 61
4.4 Model selection 62
4.5 First ANOVA table of no interaction model 64
4.6 Second ANOVA table of no interaction model 64
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4.8 Scatter plot of the observed verses predicted values for no 65 interaction model
4.9
ANOVA
table of 2-way interaction (linear x linear) model 66 4.10. Scatter plot of the observed verses predicted values for 2-way 67interaction (linear x linear) model
4.11
ANOVA
table of 2-way interaction (linear, quadratic) model 68 4.12 Scatter plot of the observed verses predicted values for 2-way 69interaction (linear, quadratic) model
4.13 Central Composite Design 70
4.14 Variable selection 70
4.15 Model selection 71
4.16
ANOVA
and predicted response selection 71 4.17ANOVA
table of linear main effect model 72 4.18 Scatter plot of the observed verses predicted values for linear main 73effect model
4.19
ANOVA
table of Lin/quad. main effects model 74 4.20 Scatter plot of the observed verses predicted values for Lin/quad. 74main effects model
4.21
ANOVA
table of Linear main eff. +2-way model 75 4.22 Scatter plot of the observed verses predicted values for Linear 76main eff. +2-way model
4.23
ANOVA
table of Lin/quad main eff. +2-ways model 77 4.24 Scatter plot of the observed verses predicted values for Lin/quad 78main eff. +2-ways model 4.25 Fitted response surface
4.26 Optimized value of the response by using the Lin/quad main eff. 80 +2-ways model.
4.27 Summary of variable 81
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4.29 Filled Ra in Table of Runs 83
4.30 Model selection 83
4.31
ANOVA
table of linear main effect only model 84 4.32 Scatter plot of the observed verses predicted values for linear main 85effect only model
4.33
ANOVA
table of Linear main eff. +2-ways model 85 4.34 Scatter plot of the observed verses predicted values for Linear 86main eff. +2-ways model
4.35
ANOVA
table of Lin/quad. main effects model 87 4.36 Scatter plot of the observed verses predicted values for Lin/quad. 88main effects model
4.37 Fitted response surface for Lin/quad. main effects model 89
4.38 Optimum values for Lin/quad. main effects model 90
4.39
ANOVA
table of Lin/quar main eff.+2ways only model 90 4.40 Scatter plot of the observed verses predicted values for Linlquar 91main eff.+2ways only model
4.41 Fitted response surface for Linlquar main eff.+2ways only model 92
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LIST OF SYMBOL
a Rake angle
Ra Arithmetic mean value, pm Rq Root-mean-square, pm
Ry Maximum peak-to-valley roughness, pm
rms Root-mean-square,, pm
F1 Tangential cutting force, N Fr Radial cutting force, N
Edge angle,
ti Thickness of the uncut layer, mm t2 Thickness of the chips produced, mm Di Indention Diameter, m
F Applied Force, kg.f D Indenter Diameter, m CS Cutting speed, if/mm
LIST OF ABBREVIATIONS
ANOVA Analysis of variance DOE Design of Experiments CNC Computer Numerical Control HBN Brinell Hardness
CHAPTER 1
INTRODUCTION
1.1 INRODUCTION
The conventional lathe machine has been used in the industry for many applications such as turning, boring, drilling, milling, planning shaping, broaching and sawing. For the Conventional Lathe Machine, the turnings are one basic machining operation. The boring operation also uses the conventional turning machine for machining. The boring operations are to enlarge a hole made previously by some other process such as drilling. The boring process makes the existing hole dimensionally more accurate than can be obtained by drilling alone and to improve the surface finish. After the boring operation the surface roughness are test using the Perthometer. The poor qualities of the surface finish are one of the industry critical issues due to the improper setting of cutting parameter. This may cause the industry to have losses due to rework and waste of time. In order to solve this problem, research studies on the Surface Roughness in the Lathe Boring Operation are carried out. In this research, the main objective will focus on the finding of the optimum parameter for single tool boring process for the best surface roughness on Mild steel.
1.2 PROJECT BACKGROUND
The lathe machine are a device that for rotating a hard object, originally wood, and later mostly metal, so that the object can be shaped by a stationary cutter (Bunch and Hellenians, 2004). The lathe machines are used in many applications these days. It can be used for turning, drilling, boring, reaming, facing, milling, planning, broaching, sawing and shaping. The boring operations are an operation using the lathe machine to
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make internal hole in the cylinder bar. Firstly, the work pieces are drilled using smaller drill bit then using a bigger drill bit. Following that, the bars are bore using the selected parameter.
Engineer trips many ways to improve the production line in order to obtain high production rate and to reduce cost. As for the boring operation, finding the optimum cutting parameter to get the best surface roughness is one of the ways to make the production rate high. Beside it can reduce the cost of the industry to do rework and to scrap the material.
Correct used of cutting parameter can produce surface roughness with high quality finish. This project focuses on the impact of the cutting parameter on the surface roughness on the Mild steel. The cutting parameter are the main key in determined the surface roughness of the material. The cutting parameter such as the cutting speed, feed rate and depth of cut might have significant influent on the resulting surface roughness. The interaction between the cutting parameter may exist and it might significantly affect the surface roughness. The impact of cutting parameter are important and yet to be investigate.
1.3 PROBLEM STATEMENT
Surface roughnesses are one of the critical issues for the lathe boring operation. The surface roughness of the product will determined the quality of it. If the surface roughness are high therefore the quality of the product are low. In the lathe boring operation, the length of the tool, tool rake angle, cutting parameter (cutting speed, feed rate, and depth of cut), type of boring bar, and tool nose radius can affect the surface roughness of the work piece. In this study, the cutting parameters chosen to be investigated are the effect of the cutting parameter on the surface roughness.
Therefore to make sure that the surface roughnesses of the product are low, the cutting parameters are control. Cutting parameter is adjusted and tunes to provide the best surface roughness. This will consumes large amount of time and effort, and still the
optimal cutting conditions may not be found. These issues of optimized parameter selection are currently being studied in this study.
The surface roughness result may not be good if the cutting parameters used are unsuitable. Thus the end product may need to go through another round of boring operation. This additional process adds to the cost of production. The relationship between the surface roughness and cutting parameter are important and yet to be investigated in this study.
1.4 PROJECT OBJECTIVE
The main objectives of this project are to study the optimum parameter for single tool boring process for the best surface roughness. The cutting parameters used to investigate were:
a) Cutting speed b) Feed rate C) Depth of cut
1.5 SCOPE OF THE PROJECT
In order to achieve the objective of this study, the scopes are list as below:
a) The cutting parameter are cutting speed, feed rate and depth of cut. b) Single inserted tool are used (Carbide).
C) The conventional lathe machine numbers 9 are used.
d) Mild steel with 38 mm diameter and length of 50 mm are used. e) The Perthometer S2 are used to measure the surface roughness. t) STATISTICA 7.1 are used to analyzed the experiment result.
1.6 SUMMARY
At the end of this research, the optimum cutting parameter for the best surface roughness could be identified.
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2.2 THEORY OF METAL CUTTING
Metal cutting are one of the most significant manufacturing processes (Chen & Smith, 1997) in the area of material removal. Machining is the process of manufacturing a component by removing the unwanted material using a machine. When metal are used it are referred as metal machining or metal cutting. The metal cutting processes are when the layer of metal from the work-piece is removed (Nagendra Parashar and Mittal, 2006). The process for the metal cutting are drilling, sawing, turning, and milling.
As stated by Mohamed (2010) the theories of metal cutting are very well established. However, some aspects have gone through revision when the experimental results showed the new parameters involved in metal cutting. Many new alloys have also been developed to react to today's applications. As a result, there will be always a need for continuous research and improvement of tool materials, cutting conditions and parameters to optimize the output.
Nagendra Parashar and Mittal (2006) has stated that, in order to remove a layer of material from the work-piece, a cutting tool is needed to penetrate into the material of work-piece and move forward to chip off a layer of material from the work-piece. This required the use of force to remove the layer. The metal cuttings are illustrated in Figure 2.1. From the figure it shows that the sharp edge of the tool will be forced into the metal and this will increase the stress of the metal. The continuing of stress on the metal will first exceed the elastic limit and then the ultimate strength of the metal. This will cause shear failure and eventually a layer of metal gets separated in the form of chips.
7 Chip Force Toot penetration (depth Of cut) (a) (b) (c
Figure 2.1: Metal cutting operation
Source: Nagendra Parashar and Mittal (2006)
The important parameters that involve in the basis of metal cutting are (Boothroyd and Knight, 1989):
a) Thickness of the uncut layer (tl,mm) b) Thickness of the chips produced (t2. mm)
C) The inclination of the chip-tool interface with respect to the cutting velocity (the face of the tool in contact with the chip are commonly known as the rake face), i.e., The rake angle a
d) The relative velocity of the work-piece and the tool
.- To make cutting possible, a clearance angle between the job and the flank surfaces are also provided. In Figure 2.2 showed the basic machining operation and important parameter.
ke surface
001-iClearance
-angle
Flank
-
surface
MA
--VWork
8Chips
thickness (t.
Uncut
thickness
(t tcPb
.
R
^e
angle
a
.
Figure 2.2: Basic machining operation and important parameter.
Source: Boothroyd and Knight (1989)
The orthogonal cuttings are when the cutting edge of the tool are perpendicular to the relative motion of the tool and work piece (Nagendra Parashar and Mittal, 2006). The orthogonal cutting operation happens on a plane and can be analyzed in a two dimensional plane (Viktor, 2010).
2.2.1 Orthogonal cutting and Oblique cutting
The book by Rao (2009) has stated that the orthogonal are a cutting process in two dimensional. The cutting processes are when the cutting edge is perpendicular to the cutting velocity, as shown in Figure 2.3 (a). As for the oblique cutting are cutting processes in three dimensional. The oblique cutting happens when the major edge of cutting are presented to the work-piece at an angle which are not perpendicular to the direction of feed motion, as shown in Figure 2.3 (b). The oblique cuttings are harder to analyzed compare to the orthogonal cutting because of its three dimensions.
(0) (b)
Figure 2.3: Cutting process, (a) Orthogonal cutting (b) Oblique cutting
Source: Rao (2009)
2.2.2 Metal Cutting in Turning Operation
Turnings are one of the most common of metal cutting operations. In turning, a stationary cutting tool (usually a single-point) is fed into a rotating work piece along its periphery or across its end or face for removing chip to obtain the required shape and dimension of a part (Isakov,2004). In other words, turning operation is where the excess material are from the work piece are removed to reduce its diameter (Nagendra Parashar and Mittal, 2006). The turning operation uses the lathe machine as shown in Figure 2.7. As stated by Mohamed (2010) the turning process requires a turning machine, work piece, fixture and cutting tools are required. The work piece with desired dimension are secured at the fixture, which are secure at the turning machine, and allowed it rotate at high speeds. The cutting tools used in the operation are a single-point cutting tool. The cutting tool feeds into the rotating work piece and cuts away material in the form of small chips to create the desired shape. (Noordin et al., 2007)
2.2.3 Tool Geometry
Geometry of the cutting tools effect the quality and productivity of the machining operation (Viktor, 2010). For cutting tools, geometry depends mainly on the properties of the tool material and the work material. In Figure 2.4 shows the typical throwaway insert tool. Figure 2.5 shows the typical right handed cutting tool. When
rInserted
cutting tool]
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the tools are in contact with the material, cutting takes place mainly over the side edge. For single point tools, the most important angles are the rake angles and the end and side relief angles (Khandey, 2009). The inclination of the side cutting edge with longitudinal axis of the shank, and the inclination of the end cutting edge with the width direction of the shank are called the side cutting edge angle and end cutting edge respectively as shown in Figure 2.6 (Juneja and Seth, 2003).
Figure 2.4: Typical throw-away insert tool
Source: El-Hofy (2007)
End (minor) =
Cutting edge
Flank face ' I •
Comer (nose)
Side face / \Major cutting edge
Figure 2.5: Typical right handed tool
11 ;Work piece End cutting - edge angle Side cutting
edge angle
-
'-
Tool axisFigure 2.6: Side and End Cutting Edge Angle
Source: Juneja and Seth (2003)
2.2.4 Cutting tool material
Proper selection of tool materials, cutting parameters, tool geometry and machine tools are essential to produce high-quality products at low cost (Seker et al., 2004). The classes of cutting tool materials currently in use for machining operation are high-speed tool steel, cobalt-base alloys, cemented carbides, ceramic, polycrystalline cubic boron nitride and polycrystalline diamond. Different machining applications require different cutting tool materials (Edalew et al., 2001).
Khandey (2009) said that the HSS tools are so named because they were developed to cut at higher speeds. Developed around 190. 0 HSS are the most highly alloyed tool steels. The tungsten (T series) was developed first and typically contains 12-18% tungsten, plus about 4% chromium and 1 - 5% vanadium. Most grades contain about 0.5% molybdenum and most grades contain 4 - 12% cobalt. It was soon discovered that molybdenum (smaller proportions) could be substituted for most of the tungsten resulting in a more economical formulation which had better abrasion resistance than the T series and undergoes less distortion during heat treatment. Consequently about 95% of all HSS tools are made from M series grades. These contain 5 - 10% molybdenum, 1.5 - 10% tungsten, 1 - 4% vanadium, 4% Chromium and many
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grades contain 5 - 10% cobalt. HSS tools are tough and suitable for interrupting cutting
and are used to manufacture tools of complex shape such as drills, reamers, taps, dies• and gear cutters. Tools may also be coated to improve wear resistance. HSS accounts for the largest tonnage of tool materials currently used. Typical cutting speeds: 10 - 60 in/mm.
As stated by Juneja and Seth (2003), the cemented carbide is divided into two, which are the tungsten carbide and alloyed tungsten carbides. The tungsten carbide consists of powered tungsten carbide (85-95%) and cobalt (5-15%). The properties of
the tool are highly depending on the content of cobalt. If the content of cobalt increases, hardness of the tools material decrease and the toughness are increased. The grain size also will affect the hardness. The finer the grain size, the greater the hardness of the tools.
Juneja and Seth (2003) also stated that the alloyed tungsten carbide has additions of carbide of titanium and niobium. Titanium carbide reduces the tendency of chips to weld to the tool. It's also decrease the process of diffusion wear of the tool and increases the hot hardness. Cemented carbide tool materials are able to retain high hardness even at temperature of 1000 °C. Other than that it can operate at a much higher cutting speed as compared to HSS.
2.3 LATHE MACHINE
The lathes are one of the most important and versatile machine tools these days. The boring operation are equivalent to turning but are performed on the internal surfaces or the work piece. Boring can be performed in many types of machine tools such as lathes, drilling machines, horizontal or vertical milling machine and machining centers. In this study the conventional lathe machine are used as shown in Figure 2.7 to carry out the boring operation. In APPENDIX Al shows the General Characteristic of Machining Processes and Typical Dimensional Tolerances.
