New Cutter Design To Minimize Part Deflection In Machining Thin Wall Low Rigidity Component.
NEW CUTTER DESIGN TO MINIMIZE PART
DEFLECTION IN MACHINING THIN WALL LOW
RIGIDITY COMPONENT
MOHD NORAZZIM BIN MOHD HASHIM
B050910049
UNIVERSITI TEKNIKAL MALAYSIA MELAKA 2012
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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
NEW CUTTER DESIGN TO MINIMIZE PART DEFLECTION IN
MACHINING THIN WALL LOW RIGIDITY COMPONENT
This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering(Process) (Hons.)
by
MOHD NORAZZIM BIN MOHD HASHIM B050910049
870917055011
FACULTY OF MANUFACTURING ENGINEERING 2012
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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: New cutter design to minimize part deflection in machining thin wall low rigidity component
SESI PENGAJIAN: 2011/12 Semester 2
Saya MOHD NORAZZIM BIN MOHD HASHIM
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
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Tarikh: 29 JUNE 2012
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DECLARATION
I hereby, declared this report entitled “New cutter design to minimize part deflection in machining thin wall low rigidity component” is the results of my own research
except as cited in references.
Signature :
Author’s Name : MOHD NORAZZIM BIN MOHD HASHIM
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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 (Process) (Hons.). The member of the supervisory is as follow:
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ABSTRAK
Untuk pengilang komponen struktur aeroangkasa, permintaan bagi alat pemotong yang berprestasi tinggi adalah pra-syarat kerana lebih daripada 80% bahan dipotong adalah untuk menghasilkan komponen monolitik. Di samping itu, kerja permintaan permukaan profil yang berkualiti yang tinggi terhadap komponen monolitic mempuayai ketebalan dinding yang nipis. Disebabkan ketebalan yang nipis pada permukaan dinidng,ubah bentuk selalu terjadi dalam pemesinan dinding nipis dimana mengakibatkan kecacatan pada ukuran permukaan. Oleh itu, proses pemesinan ini memerlukan alat pemotong khas bagi mengawal kecacatan pada permukaan. Projek ini, cuba untuk menyiasat dan menganalisis kesan bilangan gigi pada alat pemotong terhadap magnitud ralat ukuran permukaan dan prestasi pemesinan apabila pemesinan dilakukan pada bahagian dinding yang nipis dan ketegaran rendah. Pada akhir pemesinan, apa yang dapat dilihat adalah keputusan analisis dari sudut kerosakan pada permukaan, daya pemotongan dan kekasaran permukaan dengan mengunakan alat pemotong yang berbeza gigi. Analisis akan menunjukkan bahawa samada bilangan gigi pada alat pemotong menpengaruhi benda kerja. Selain itu, daya permotongan menpengaruhi kerosakan pada permukaan.
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ABSTRACT
For aerospace structural component manufacturer, the demand for the high-performance cutting tools is pre-requisite as more than 80% of the material is cut away to produce the monolithic component. In addition, this works demand high quality surface profile as most of the monolithic component contains a thin-wall feature. Because of the poor stiffness of thin-wall feature, deformation is more likely to occur in the machining of thin-wall part which result a dimensional surface errors. Thus, this machining process needs a special cutting tool for effectively control the surface errors. This project attempts to investigate and analyse the effect of flute number of end mill cutter on the magnitude of dimensional surface errors and machining performance when machining thin-wall low rigidity part. At the end of machining, what is seen are the results of analysis of surface error, cutting force and surface roughness by using different flutes. The analysis will show that either the number of flute on cutting tool will influence the workpiece surface. In addition, cutting force is influence the surface error
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DEDICATION
This dedication is for my mother and father, who always pray for my safety and health. Thanks to them because always be my side no matter what happen. Without blessing from them, maybe I’m not here. All guidance and advice given by
them always I follow.For me, their prayer is keys of my success. I am grateful because I have them as my parents. Thank you, Allah.
Also thanks a lot to my supervisor, Dr Raja Izamshah Bin Raja Abdullah for their support and care.
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ACKNOWLEDGEMENT
Alhamdulillah, Thanks to the entire Almighty from Allah for giving me all the strength and good health to complete this report without problems and barriers. This report is finally completed with much assistance of many people.
I would like to express the deepest appreciation to Universiti Teknikal Melaysia Melaka for providing such a brilliant facility such as equipment and machine for me to fulfil PSM requirement that’s need to use while the project is carry on .
Besides that, I am heartily thankful to my supervisor, En. Raja Izamshah Bin Raja Abdullah, whose encouragement, guidance and support from the initial to the final level enabled me to develop an understanding of the research. I am truly grateful for his the time spent proofreading and correcting my many mistakes, his tolerance of my mistakes, and his commitment to my future career.
In addition, I would like to thank all manufacturing engineering department lab staff for giving me an opportunity to work in a good and productive environment. Their continuous support and guidance whenever problems occurred while I was performing new task is really an encouragement in making me to perform at my very best. This has partly contributed to the success of my research and the completion of this ‘Projek Sarjana Muda’.
Last but not least I would like to thank my friends especially those who help to contribute the idea and solution while the research is carry on. Thank you.
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TABLE OF CONTENT
Abstrak i
Abstract ii
Dedication iii
Acknowledgement iv
Table of Content v
List of Tables vii
List of Figures viii
List Abbreviations, Symbols and Nomenclature x
CHAPTER 1 : INTRODUCTION 1
1.1 Research Background 1
1.2 Problem Statement 2
1.3 Research Objectives 3
1.4 Scope of Project 3
CHAPTER 2: LITERATURE RIVIEW 4
2.1 Related Study 4
2.2 End Milling 6
2.3 Geometric Feature of End Mill 7
2.4 Flute 10
2.4.1 Effect of flute number 11
2.5 Thin wall part 11
2.6 Cutting tool material 12
2.6.1 High Speed Steel 13
2.6.2 Carbide 13
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CHAPTER 3: METHODOLOGY 15
3.1 Introduction 15
3.2 Flow Chart 16
3.3 Cutting tool parameter 17
3.4 Work Piece 17
3.4.1 Part Modelling 17
3.4.2 Machining process 21
3.5 Test/Machining 24
3.5.1 Performance Measurement 24
3.6 Summary 27
CHAPTER 4: RESULT & ANALYSIS
4.1 Introduction 28
4.2 Surface Error 30
4.2.1 3D Graph 30
4.2.2 3D Graph thickness 6-4mm 31
4.2.3 Analysis 6-4mm 34
4.2.4 3D Graph thickness 4-2mm 34
4.2.5 Analysis 4-2mm 37
4.3 Cutting force, Fx 37
4.3.1 Cutting Force Graph 6-4mm 38
4.3.2 Analysis cutting force 40
4.3.3 Cutting Force 4-2 mm 41
4.3.4 Analysis cutting force 42
4.4 Surface Roughness 43
4.4.1 Thickness 6 mm to 4 mm 44
4.4.2 Thickness 4 mm to 2 mm 45
CHAPTER 5 CONCLUSION 48
5.1 Conclusion 48
REFERENCES
APPENDICES
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B PSM 2 Gantt Chart
C Reading of surface error of 6 - 4mm (4 and 5 flute) D Reading of surface error of 6 - 4mm (6 and 7 flute) E Reading of surface error of 6 - 4mm (8 flute) F Reading of surface error of 4 - 2mm (4 and 5 flute) G Reading of surface error of 4 - 2mm (6 and 7 flute) H Reading of surface error of 4 - 2mm (8 flute)
I Surface roughness result 6-4 mm (4, 5 and 6 flute) J Surface roughness result 6-4 mm (7 and 8 flute) K Surface roughness result 4 -2 mm (4, 5 and 6 flute) L Surface roughness result 4 -2 mm (7 and 8 flute)
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LIST OF TABLES
2.1 Feature Dimension 8
3.1 Parameter 16
3.2 Dimension Thin wall 23
4.1 Flute 28
4.2 Cutting Tool Dimension 29
4.3 Thickness 6mm to 4mm 43
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LIST OF FIGURES
1.1 Aerospace monolithic component 1
2.1 Variety of end mills 6
2.2 Two Flutes 7
2.3 Multi Flute 7
2.4 Geometry Feature 8
2.5 Angle Geometry 8
2.6 Geometry of End mill 9
2.7 Rake Angle 9
2.8 Flute 10
2.9 Thin wall work piece 12
3.1 Methodology Flow Chart 16
3.2 Dimension (50 mm x 120 mm) 17
3.3 Extrude/Pad (11.8 mm) 18
3.4 Solid Part 18
3.5 Constraint 19
3.6 Extrude/Pad (38.1 mm) 19
3.7 Final part 20
3.8 Isometric view 20
3.9 Thin wall part before machining 21
3.10 Start machining 21
3.11 Overall Machining 22
3.12 Stock Aluminium 23
3.13 Thin wall dimension 23
3.14 Points to measure 24
3.15 Mitutoyo CNC CMM 25
3.16 Mitutoyo Microscope 26
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3.18 Mitutoyo surface roughness tester 27
3.19 Example Ra Graft 27
4.1 Five Cutting tool 28
4.2 Cutting Tool Dimension 29
4.3 Workpiece (Thin wall part) 30
4.4 Zone 31
4.5 4 Flute (6-4mm) 31
4.6 5 Flute (6-4mm) 32
4.7 6 Flute (6-4mm) 32
4.8 7 Flute (6-4mm) 33
4.9 8 Flute (6-4mm) 33
4.10 4 Flute (4-2mm) 34
4.11 5 Flute (4-2mm) 35
4.12 6 Flute (4-2mm) 35
4.13 7 Flute (4-2mm) 36
4.14 8 Flute (4-2mm) 36
4.15 4 Flute graph (6-4mm) 38
4.16 5 Flute graph (6-4mm) 38
4.17 6 Flute graph (6-4mm) 39
4.18 7 Flute graph (6-4mm) 39
4.19 8 Flute graph (6-4mm) 40
4.20 4 Flute graph (4-2mm) 41
4.21 5 Flute graph (4-2mm) 41
4.22 6 Flute graph (4-2mm) 42
4.23 7 Flute graph (4-2mm) 42
4.24 8 Flute graph (4-2mm) 43
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LIST OF ABBREVIATIONS, SYMBOLS AND
NOMENCLATURE
% - Percent
Al - Aluminium
CAM - Computer Aided Manufacturing
Catia - Computer Aided Three-Dimensional Interactive CMM - Coordinate Measuring Machine
CNC - Computer Numerical Control
Cº - Degree Celsius
FEA - Finite Element Analysis HSS
HV
- -
High Speed Steel Hardness Vickel
m - meter
min - minute
mm - millimetre
Mpa - Mega Pascal
NC - Numerical Control
Ra - Arithmetic Average of Absolute Value RPM - Revolution Per Minute
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1
1.1 Research Background
Demand for the next generation, cost effective, high performance aircrafts has motivating the aerospace industry to use non-traditional materials and new aircraft structural design. New aircraft are design with one piece flow of monolithic component to replace large number of assembled component. This new monolithic structural components allows for higher quality and reduce the manufacturing times.
Figure 1.1: Aerospace monolithic component.
The monolithic component consists of several thin-wall rib and flange sections that need to be machine as shown in Figure 1.1. Because of the poor stiffness of thin-wall feature, deformation is more likely to occur in the machining of thin-wall part which resulting a dimensional surface errors. The surface dimensional error is induced mainly by the deflection of the tool and the workpiece during milling, which results
INTRODUCTION
CHAPTER 1
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2 in a deviation of the depth of cut. If the cutter and workpiece have high rigidity, the deflection of the cutter and workpiece are small and can be neglected in the distribution of surface dimensional error. However, in the peripheral milling of a very flexible component, the deflection is significant. The process is further complicated by periodically varying milling forces, which statically and dynamically excite the tool and part structures, leading to significant and often unpredictable deflections.
1.2 Problem Statement
Machining errors can be broadly classified as geometric errors, thermal induced errors cutting force induced errors and other errors. The errors caused by cutting forces depend on the type of tool and workpiece and the specific cutting conditions and parameters. For machining low rigidity thin-walled parts, the force induced part deflection has a significant contribution to the total surface error. The tight dimensional tolerance of aerospace component poses a great challenge for the manufacturer especially for machining component that contains a thin wall feature.
Tool geometry has a direct influence on the cutting performance such as the cutting forces, quality of machined surface, shapes accuracy, cutting edge wear and tool life. The geometric parameters of end mills include the number of flute, edge shape, rake angle, relief angle, helix angle and clearance angle. Each of the geometric features has their own function and need to be considered for a specific machining application.
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3
1.3 Research Objectives
Most of the existing research on machining thin-wall component concentrated on the process planning, little attention is emphasize on the effect of cutting tool on the occurrence of the surface error and machining performance. Driven by the need to constantly increase the machining efficiency and part accuracy, the objectives of this project are to:
a) Investigate and analyse the effect of end mill flute number on the magnitude of dimensional surface errors when machining thin-wall low rigidity part,
b) Investigate and analyse the effect of end mill flute number on the machining performance namely cutting forces and surface roughness.
1.4 Scope of Project
This project focuses on the effects number of flute of end mill cutter on the magnitude of dimensional surface errors and machining performance when machining thin-wall low rigidity part. Five carbide end mill cutters with different number of flute will be design and fabricate using a CNC tool cutter grinder machine. Then, a side-milling experiment will be conduct on aluminium thin-wall workpiece to analyse the effects on number of end mill flute. The evaluation of machining performance consists of the magnitudes of surface errors, cutting forces and surface roughness.
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4
2.1 Related Study
So far, there is still no other specific journal research about the cutting tool for end mill but there is some other journal that can be related to cutting tool which is cutting force. In their study, cutting force in machining of thin wall parts is due of variable part or tool deflection. All the study talk about the a new analytical force model, a method that predicts cutting force, develop a cutting force model, proposed a mechanistic model for cutting force and approach to identify cutting force coefficients.
Min et.al (2006) propose a new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients. State that the total cutting forces can be separated into two terms which is nominal component independent of the run out and a perturbation component induced by the run out. To calibrate the cutting force coefficients the instantaneous value of nominal component is used. In early studies of milling process, Min et.al (2006), state that cutting force models were develop based on the nominal instantaneous uncut chip thickness without run out and more milling force models were proposed. Also state that dynamometer can be used to measure a cutting force. Form other viewpoint, Cho et.al proposed an alternative approach to use instantaneous cutting force for the calibration of cutting force coefficients and the evaluation of run out parameters in end milling. Advantage of this method is only needs a few test to do calibration procedure which is can reduce large number of experiment or testing.
LITERATURE REVIEW
CHAPTER 2
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5 S.Ratchev et.al (2004) study about a flexible force model for end milling of low-rigidity parts which is there is a high complexity associated with modeling of cutting forces in machining of thin-wall parts due to the variable part/tool deflection and changing tool immersion angle. The cutting forces in machining of low-rigidity deflecting parts depend on the chip thickness which is a function of the tool immersion angle. In machining low-rigidity parts the tool immersion angle is a function of the part deflection which itself depends on the cutting forces. S.Ratchev et.al (2004) study the develop method from another research based on cutting force of oblique cutting. For example, Budak et.al (1996), predicts the milling force coefficients from an orthogonal cutting database and a generic oblique cutting analysis where this method can be applied to more complex tool designs by eliminates the need for experimental calibration for each milling tool geometry. Based on theory of oblique cutting, Ikua et.al (2001), predicts the cutting force and machining error assuming instantaneous rigid force model in calculating chip thickness and cutting forces by presented a theoretical model. Meanwhile, Klineet.al (1982) using the finite element (FE) method to model the part to proposed a mechanistic model for cutting force prediction combined with a model for cutter and work piece deflections. Feng and Meng (1994) developed a cutting force model based on the mechanistic principles of metal cutting. Also propose a mechanistic force model for predicting the machining errors caused by tool deflection is Lim et.al (1995).
2.2 End Milling
End mill is a type of milling cutter which is cutting tool that used for many applications in industrial milling. In application of end mills is used in milling applications such as tracer milling profile milling, face milling, and plunging. In selection and use of end mills, some precautions should be taken for best result also for the safety. An ample power of milling machine should be used and also by select a proper design of end mill and mount it with the least possible overhang. It important to ensure that end mill is sharp and must run as concentric as possible. (Metal Cutting Tool Handbook 1989)
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6 The most common ones that we always use will getting started are 2-flute and 4-flute end mills. Milling are also have more than 2 flute which is depends on it applications. They are usually made from high speed steel (HSS) or carbide and have one or more flutes. End milling cutter generate two work pieces surfaces at the same time which is the cutting edges are located on both the end face and periphery of cutter body. For this end milling usually used in facing, profiling, slabbing, shoulder and slotting.
Figure 2.1: Variety of end mills (Hoose, 2001).
Several basic must be considered to determine the selection either a two flute or a multiple flute end mill.
a) Type of cut
b) Chip space required c) Production rate desired d) Surface finish required
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11
2.4.1 Effect of flute number
The two-flute end mill has the greatest amount of flute space allowing for more chip carrying capacity. Used primarily in slotting and pocketing of non-ferrous materials where chip removal is a concern. Only have two teeth and designed to cut the center of the mill. Three Flute,While this tool has the same flute space as two flutes, it has a larger cross-sectional area providing for greater strength and the ability to pocket and slot both ferrous and non-ferrous materials. Four/Multiple Flute, Suitable for peripheral and finish milling. The additional flutes allow faster feed rates, but due to the reduced flute space, chip removal may be a problem. Advantages, produces a much finer finish than two and three flute tools.
2-Flute mills are generally used for cutting slots or grooves, while 4-flute mills are more often used for surface milling, using the end of the mill. (Hoose, 2001). Comparison between two flute end mills with multiple flute end mills is two flute end mills have greater chip handling capacity than multiple flute end mills and also for the cutting, two flute end mills are for center cutting while multiple flute end mills for both center cutting and non-center cutting. For produce a better finishing, if we run feed rate at the same time between these two types of flute, multiple flute end mils may produce a finer finishes and longer tool life than two flutes. (Metal Cutting
Tool Handbook, 1989).
2.5 Thin wall part
The issue of thin-walled milling is very extensive. Machining of thin-walled parts is key process in aerospace industry. The part deflection caused by the cutting force is difficult to predict and control. In order to predict the cutting deformation of thin-walled part in milling process, there are lot of method and research that already done by researchers to get the result. In the aviation industry, the thin-walled structural parts are widely used. Due to its low rigidity, the thin-walled parts easily deform during the cutting process. This makes the precision difficult to master. The resulting errors are usually compensated through repetitive feeding, numerical control compensation and manual calibration. However, these methods create low efficiency
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2 in a deviation of the depth of cut. If the cutter and workpiece have high rigidity, the deflection of the cutter and workpiece are small and can be neglected in the distribution of surface dimensional error. However, in the peripheral milling of a very flexible component, the deflection is significant. The process is further complicated by periodically varying milling forces, which statically and dynamically excite the tool and part structures, leading to significant and often unpredictable deflections.
1.2 Problem Statement
Machining errors can be broadly classified as geometric errors, thermal induced errors cutting force induced errors and other errors. The errors caused by cutting forces depend on the type of tool and workpiece and the specific cutting conditions and parameters. For machining low rigidity thin-walled parts, the force induced part deflection has a significant contribution to the total surface error. The tight dimensional tolerance of aerospace component poses a great challenge for the manufacturer especially for machining component that contains a thin wall feature. Tool geometry has a direct influence on the cutting performance such as the cutting forces, quality of machined surface, shapes accuracy, cutting edge wear and tool life. The geometric parameters of end mills include the number of flute, edge shape, rake angle, relief angle, helix angle and clearance angle. Each of the geometric features has their own function and need to be considered for a specific machining application.
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3 1.3 Research Objectives
Most of the existing research on machining thin-wall component concentrated on the process planning, little attention is emphasize on the effect of cutting tool on the occurrence of the surface error and machining performance. Driven by the need to constantly increase the machining efficiency and part accuracy, the objectives of this project are to:
a) Investigate and analyse the effect of end mill flute number on the magnitude of dimensional surface errors when machining thin-wall low rigidity part,
b) Investigate and analyse the effect of end mill flute number on the machining performance namely cutting forces and surface roughness.
1.4 Scope of Project
This project focuses on the effects number of flute of end mill cutter on the magnitude of dimensional surface errors and machining performance when machining thin-wall low rigidity part. Five carbide end mill cutters with different number of flute will be design and fabricate using a CNC tool cutter grinder machine. Then, a side-milling experiment will be conduct on aluminium thin-wall workpiece to analyse the effects on number of end mill flute. The evaluation of machining performance consists of the magnitudes of surface errors, cutting forces and surface roughness.
(3)
4 2.1 Related Study
So far, there is still no other specific journal research about the cutting tool for end mill but there is some other journal that can be related to cutting tool which is cutting force. In their study, cutting force in machining of thin wall parts is due of variable part or tool deflection. All the study talk about the a new analytical force model, a method that predicts cutting force, develop a cutting force model, proposed a mechanistic model for cutting force and approach to identify cutting force coefficients.
Min et.al (2006) propose a new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients. State that the total cutting forces can be separated into two terms which is nominal component independent of the run out and a perturbation component induced by the run out. To calibrate the cutting force coefficients the instantaneous value of nominal component is used. In early studies of milling process, Min et.al (2006), state that cutting force models were develop based on the nominal instantaneous uncut chip thickness without run out and more milling force models were proposed. Also state that dynamometer can be used to measure a cutting force. Form other viewpoint, Cho et.al proposed an alternative approach to use instantaneous cutting force for the calibration of cutting force coefficients and the evaluation of run out parameters in end milling. Advantage of this method is only needs a few test to do calibration procedure which is can reduce large number of experiment or testing.
LITERATURE REVIEW
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5 S.Ratchev et.al (2004) study about a flexible force model for end milling of low-rigidity parts which is there is a high complexity associated with modeling of cutting forces in machining of thin-wall parts due to the variable part/tool deflection and changing tool immersion angle. The cutting forces in machining of low-rigidity deflecting parts depend on the chip thickness which is a function of the tool immersion angle. In machining low-rigidity parts the tool immersion angle is a function of the part deflection which itself depends on the cutting forces. S.Ratchev et.al (2004) study the develop method from another research based on cutting force of oblique cutting. For example, Budak et.al (1996), predicts the milling force coefficients from an orthogonal cutting database and a generic oblique cutting analysis where this method can be applied to more complex tool designs by eliminates the need for experimental calibration for each milling tool geometry. Based on theory of oblique cutting, Ikua et.al (2001), predicts the cutting force and machining error assuming instantaneous rigid force model in calculating chip thickness and cutting forces by presented a theoretical model. Meanwhile, Klineet.al (1982) using the finite element (FE) method to model the part to proposed a mechanistic model for cutting force prediction combined with a model for cutter and work piece deflections. Feng and Meng (1994) developed a cutting force model based on the mechanistic principles of metal cutting. Also propose a mechanistic force model for predicting the machining errors caused by tool deflection is Lim et.al (1995).
2.2 End Milling
End mill is a type of milling cutter which is cutting tool that used for many applications in industrial milling. In application of end mills is used in milling applications such as tracer milling profile milling, face milling, and plunging. In selection and use of end mills, some precautions should be taken for best result also for the safety. An ample power of milling machine should be used and also by select a proper design of end mill and mount it with the least possible overhang. It important to ensure that end mill is sharp and must run as concentric as possible. (Metal Cutting Tool Handbook 1989)
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6 The most common ones that we always use will getting started are 2-flute and 4-flute end mills. Milling are also have more than 2 flute which is depends on it applications. They are usually made from high speed steel (HSS) or carbide and have one or more flutes. End milling cutter generate two work pieces surfaces at the same time which is the cutting edges are located on both the end face and periphery of cutter body. For this end milling usually used in facing, profiling, slabbing, shoulder and slotting.
Figure 2.1: Variety of end mills (Hoose, 2001).
Several basic must be considered to determine the selection either a two flute or a multiple flute end mill.
a) Type of cut
b) Chip space required c) Production rate desired d) Surface finish required
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11
2.4.1 Effect of flute number
The two-flute end mill has the greatest amount of flute space allowing for more chip carrying capacity. Used primarily in slotting and pocketing of non-ferrous materials where chip removal is a concern. Only have two teeth and designed to cut the center of the mill. Three Flute,While this tool has the same flute space as two flutes, it has a larger cross-sectional area providing for greater strength and the ability to pocket and slot both ferrous and non-ferrous materials. Four/Multiple Flute, Suitable for peripheral and finish milling. The additional flutes allow faster feed rates, but due to the reduced flute space, chip removal may be a problem. Advantages, produces a much finer finish than two and three flute tools.
2-Flute mills are generally used for cutting slots or grooves, while 4-flute mills are more often used for surface milling, using the end of the mill. (Hoose, 2001). Comparison between two flute end mills with multiple flute end mills is two flute end mills have greater chip handling capacity than multiple flute end mills and also for the cutting, two flute end mills are for center cutting while multiple flute end mills for both center cutting and non-center cutting. For produce a better finishing, if we run feed rate at the same time between these two types of flute, multiple flute end mils may produce a finer finishes and longer tool life than two flutes. (Metal Cutting
Tool Handbook, 1989). 2.5 Thin wall part
The issue of thin-walled milling is very extensive. Machining of thin-walled parts is key process in aerospace industry. The part deflection caused by the cutting force is difficult to predict and control. In order to predict the cutting deformation of thin-walled part in milling process, there are lot of method and research that already done by researchers to get the result. In the aviation industry, the thin-walled structural parts are widely used. Due to its low rigidity, the thin-walled parts easily deform during the cutting process. This makes the precision difficult to master. The resulting errors are usually compensated through repetitive feeding, numerical control compensation and manual calibration. However, these methods create low efficiency