PERFORMANCE OF UNCOATED CUTTING TOOLS WHEN …umpir.ump.edu.my/id/eprint/1836/1/Mohd_Fahmi_Md_Yusuf_(_CD_4948_).pdf · mild steel and 79.55% accuracy for aluminium alloy which reliable

PERFORMANCE OF UNCOATED CUTTING TOOLS WHEN MACHINING MILD

STEEL AND ALUMINIUM ALLOY

MOHD FAHMI BIN MD YUSUF

Thesis submitted in fulfilment of the requirements

for the award of the degree of

Bachelor of Mechanical Engineering

Faculty of Mechanical Engineering

UNIVERSITI MALAYSIA PAHANG

DECEMBER 2010

ii

SUPERVISOR’S DECLARATION

I hereby declare that I have checked this project and in my opinion, this project is

adequate in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering.

Signature ....................................

Name of Supervisor: DR KUMARAN KADIRGAMA

Position: LECTURER OF MECHANICAL ENGINEERING

Date:

iii

STUDENT’S DECLARATION

I hereby declare that the work in this project is my own except for quotations and

summaries which have been duly acknowledged. The project has not been accepted for

any degree and is not concurrently submitted for award of other degree.

Signature ..................................

Name: MOHD FAHMI BIN MD YUSUF

ID Number: MA 07079

Date:

v

ACKNOWLEDGEMENTS

I am grateful and would like to express my sincere gratitude to my supervisor Dr

Kumaran Kadirgama and Mr Mohamad b Mat Noor for his germinal ideas, invaluable

guidance, continuous encouragement and constant support in making this research

possible. He has always impressed me with his outstanding professional conduct, his

strong conviction for science, and his belief that a Degree program is only a start of a

life-long learning experience. I appreciate his consistent support from the first day I

applied to graduate program to these concluding moments. I also sincerely thanks for

the time spent proofreading and correcting my many mistakes.

My sincere thanks go to all my mates and members of the staff of the

Mechanical Engineering Department, UMP, who helped me in many ways and made

my stay at UMP pleasant and unforgettable. Many special thanks go to instructor

engineer and assistance instructor for their excellent co-operation, inspirations and

supports during this study.

I acknowledge my sincere indebtedness and gratitude to my parents for their

love, dream and sacrifice throughout my life. I cannot find the appropriate words that

could properly describe my appreciation for their devotion, support and faith in my

ability to attain my goals. Special thanks should be given to my committee members. I

would like to acknowledge their comments and suggestions, which was crucial for the

successful completion of this study.

vi

ABSTRACT

This paper discuss of the performance of uncoated carbide cutting tools in milling by

investigating through the surface roughness. Response Surface Methodology (RSM) is

implemented to model the face milling process that are using four insert of uncoated

carbide TiC as the cutting tool and mild steel AISI1020 and aluminium alloy AA6061

as materials due to predict the resulting of surface roughness. Data is collected from

HAAS CNC milling machines were run by 15 samples of experiments for each material

using DOE approach that generate by Box-Behnkin method due to table design in

MINITAB packages. The inputs of the model consist of feed, cutting speed and depth of

cut while the output from the model is surface roughness. Predictive value of surface

roughness was analyzed by the method of RSM. The model is validated through a

comparison of the experimental values with their predicted counterparts. A good

agreement is found where from the RSM approaches show the 76.51% accuracy for

mild steel and 79.55% accuracy for aluminium alloy which reliable to be use in Ra

prediction and state the feed parameter is the most significant parameter followed by

depth of cut and cutting speed influence the surface roughness. The proved technique

opens the door for a new, simple and efficient approach that could be applied to the

calibration of other empirical models of machining

vii

ABSTRAK

Kertas kajian ini membincangkan tentang prestasi alat pemotong karbida tidak bersalut

dengan menyiasat melalui kekasaran permukaan dalam proses pengilingan. Pendekatan

RSM digunakan dalam menganalisis nilai kekasaran permukaan mild steel AISI1020

dan aluminium aloi AA6061 iaitu bahan eksperimen yang di potong oleh empat sisipan

karbida yang tidak bersalut titanium karbida (TiC). Data dikumpul dari 15 sample

eksperimen untuk setiap bahan yang direka dari kaedah Box-Behnkin di dalam

perisian MINITAB mengunakan pendekatan DOE dan mesin pengiling HAAS CNC.

Data masuk adalah kelajuan memotong,kedalaman memotong dan kadar pergerakan

pemotong dan data yang dinilai adalah kekasaran permukaannya. Nilai ramalan

kekasaran permukaan dianalisis oleh kaedah RSM. Kemudian nilai analisis terbabit

akan dibandingkan dengan nilai eksperimen. Pendekatan RSM menunjukan ketepatan

ramalan sebanyak 76.51% untuk mild steel dan 79.55% untuk aluminium aloi yang

boleh diguna pakai dalam ramalan kekasaran permukaan dan kadar pergerakan

pemotong memainkan peranan yang penting dalam mempengaruhi nilai kekasaran

permukaan di ikuti oleh kedalaman dan kelajuan pemotongan.Teknik dan pendekatan

ini terbukti membuka pintu untuk pendekatan baru, mudah dan efisien yang boleh

diterapkan dalam mendapatkan nilai kekasaran permukaan yang diperlukan.

viii

TABLE OF CONTENTS

Page

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

DEDICATIONS iv

ACKNOWLEDGEMENTS v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES x

LIST OF FIGURES xi

CHAPTER 1 INTRODUCTION

1.1 Project Background 1

1.2 Problem statements 2

1.3 Objectives 3

1.4 Project scopes 3

CHAPTER 2 LITERATURE REVIEW

2.1 Milling Machine 4

2.1.1 Type Of Milling Machine 5

2.1.2 Different Operation Of Milling Machine 6

2.2 Aluminium Alloy 7

2.3 Mild Steel 7

2.4 Uncoated Carbide Cutting Tools 8

2.4.1 Tungsten Carbide 8

2.4.2 Titanium Carbide 9

2.5 Surface Roughness 9

2.5.1 Measuring Surface Roughness 10

CHAPTER 3 METHODOLOGY

3.1 Introduction 12

3.2 Experiment Setup 14

3.2.1 Type Of Material 14

ix

3.2.2 Size Of Workpiece 15

3.2.3 Type Of Cutting Tool 15

3.3 Design Of Experiment (DOE) 16

3.3.1 RSM Method 16

3.3.2 Full Experiment Design 17

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 19

4.2 Preliminary Finding Of Research 19

4.3 Result Of Surface Roughness 20

4.4 Analysis In Identifying Significant Factor 21

4.5 Comparison Of Surface Roughness Of Mild Steel And

Aluminium Alloy

25

4.6 Surface Plot And Contour Plot For Mild Steel 28

4.6.1 High Hold Value Of Each Parameter 28

4.6.2 Middle Hold Value Of Each Parameter 31

4.6.3 Low Hold Value Of Each Parameter 34

4.7 Surface Plot And Contour Plot For Aluminium Alloy 37

4.7.1 High Hold Value Of Each Parameter 37

4.7.2 Middle Hold Value Of Each Parameter 40

4.7.3 Low Hold Value Of Each Parameter 43

CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1 Introduction 46

5.2 Summary 46

5.3 Conclusion 47

5.4 Recommendations 47

REFERENCES 49

x

LIST OF TABLE

Table No. Title

Page

3.1 Properties of Aluminium Alloy and Mild Steel 14

3.2 TiC cutting tool properties 15

3.3 Factor and level used in the experiment 17

3.4 Experiment design for Mild Steel 17

3.5 Experiment design for Aluminium Alloy 18

4.1 Result of Surface Roughness for Mild Steel 20

4.2 Result of Surface Roughness for Aluminium Alloy 21

4.3 Estimated Regression Coefecient for Ra of Mild Steel 22

4.4 Analysis of Variance (ANOVA) of roughness average (Ra)

for Mild Steel

22

4.5 Estimated Regression Coeffecient for Ra of Aluminium Alloy 23

4.6 Analysis of Variance (ANOVA) of Roughness average (Ra)

for Aluminium Alloy

24

xi

LIST OF FIGURE

Figure No. Title

Page

2.1 Vertical milling machine

5

2.2 Horizontal milling machine

5

2.3 Different operation of miling machine

6

3.1 Procedure flow diagram

13

3.2 Design of workpiece

15

4.1 Normal probability plot for Mild Steel

22

4.2 Normal probability plot for Aluminium Alloy

23

4.3 Comparison on experiment data of Ra between mild steel and

aluminium alloy

25

4.4 Surface plot of Depth of cut vs Cutting speed

28

4.5 Contour plot of Depth of cut vs Cutting speed

28

4.6

Surface plot of Feed vs Cutting speed 29

4.7

Contour plot of Feed vs Cutting speed 29

4.8 Surface plot of Feed vs Depth of cut 30

4.9 Contour plot of Feed vs Depth of cut 30

4.10 Surface plot of Depth of cut vs Cutting speed 31

4.11 Contour plot of Depth of cut vs Cutting speed 31

4.12 Surface plot of Feed vs Cutting speed 32

4.13 Contour plot of Feed vs Cutting speed 32





xii























CHAPTER 1

INTRODUCTION

1.1 PROJECT BACKGROUND

As an engineer, production of new products is a duty to ensure that an industry

increases developed to compete with other industries. Indirectly, the use of cutting tools

become an important elements in the engineering world. Nowadays, various types of

cutting tools have been produced to ensure progress in several important aspects of each

cutting tool such as tool life and surface roughness. Each cutting tool in the world has

certain features. The use is also based on those features. However, each cutting tool has

advantages and limits use of its own.

Uncoated carbides cutting tools are widely used in the metal-working industry

and provide the best alternative for most milling operations. Carbide is also known as

cemented or sintered carbides were introduce in 1930. because of their high thermal

conductivity, and low thermal expansion, carbide are among the most important,

versatile, and cost-effective tool and die materials for a wide range of applications. The

two major groups of carbides used for machining are tungsten carbide and titanium

carbide. This cutting tool cannot be used at low speed because of cold welding of chips

and microchipping.

When machining using carbides under typical cutting conditions, the gradual

wear of the flank and rake faces is the main process by which a cutting tool fails.

Venkatesh carried out tool wear investigations on some cutting tool materials. He

plotted tool life curves using the flank wear criterion and obtained that the tool life of

carbides decreased quickly at higher speed.

2

Some authors affirm that the flank wear in carbide tools initially occurs due to

abrasion and as the wear process progresses, the temperature increases causing diffusion

to take place. Actually, the fact that abrasive wear may occur in metal cutting is not

surprising since there are many hard abrasive particles present in metals, especially in

steel.

1.2 PROBLEM STATEMENTS

Performance of cutting tools is very important in metal-working industries to

reduce time and cost while increasing the production. The use of coolant to increase tool

life is an issue with many differing views. In contrast, others have found that coolant

promotes tool wear in machining. The inherent brittleness of carbides renders them

susceptible to severe damage by cracking if sudden loads of thermal gradients are

applied to their edge. König and Klinger also claimed that better performance of

carbides was obtained under dry cutting. But the tools also can damage under dry

cutting. The other factor that relate to the performance of the tool tip is the cutting force

and feed rate. Carbide cutting tools was design for the high speed machining, but if the

cutting speed is too high, it will increase the temperature of cutting tool and may cause

the hardness of the tool decrease. Aluminium alloy and mild steel are two different

materials that are widely used in engineering due to their machining performance and

acceptable in many applications. Other than that, this material has excellent properties

and low price that make them the first choice in selecting materials. However, both of

the materials have a different hardness and characteristic which will give different

impact to the cutting tools and surface of the materials. So, this experiment is about to

find the proper material to be cut by this cutting tools.

3

1.3 OBJECTIVES OF THE PROJECT

(i) To investigate the finest surface produce from face milling machining of

uncoated carbide cutting tools to the mild steel and aluminium alloy.

(ii) To determine the performance of the uncoated carbide cutting tools in face

milling process for machining aluminium alloy and mild steel.

1.4 PROJECT SCOPES

Scope of the project are:

(i) The cutting operation of aluminium alloy and mild steel is using CNC

milling machine under dry cutting. The process is face milling.

(ii) Response Surface Method will be use to construct the experiment and

analize the data from experiment.

(iii) Taking the data on surface roughness using MPI Mahr perthometer.

(iv) Determine optimum performance of uncoated carbide cutting tools in milling

operation for aluminium alloy and mild steel by vary machining parameter

which is cutting speed, feed and depth of cut.

CHAPTER 2

LITERATURE REVIEW

2.1 MILLING MACHINE

Milling is the process of cutting away material by feeding a workpiece past a

rotating multiple tooth cutter. The cutting action of the many teeth around the milling

cutter provides a fast method of machining. The machined surface may be flat,angular,

or curved. The surface may also be milled to any combination of shapes. The machine

for holding the workpiece, rotating the cutter, and feeding it is known as the Milling

machine. Milling machine may be operated manually or under computer numerical

control (CNC). Milling is the most important and widely useful operation process for

material removal compared to turning, grinding and drilling. Within these metal cutting

processes, the end-milling process is one of the most fundamental metal removal

operations used in the manufacturing industry (Lou & Chen, 1999). Milling can be

defined as machining process in which metal is removed by a rotating multiple-tooth

cutter with each tooth removes small amount of metal in each revolution of the spindle.

Because both workpiece and cutter can be moved in more than one direction at the same

time, surfaces having almost any orientation can be machined. The study conducted by

M. Rahman et al. (1999) reveals that for a given machine tool and the workpiece setup,

the cutting parameters such as speed, feed, depth of cut and tool nose radius have a

considerable influence on the surface roughness.

http://www.mfg.mtu.edu/cyberman/machining/trad/milling/millmach.html



5

2.1.1 Type Of Milling Machine

Two type of milling machine are vertical and horizontal milling machine.

Figure 2.1: Vertical milling machine

Figure 2.2: Horizontal milling machine

Vertical

positioning screw

Crossfeed handle

Column

Quill

Vertical feed crank

Saddle

Table

Knee

Base

Table

handwheel

Ram Vertical head

Vertcal

positioning screw

Table

handwheel

Column

Table

transmission

Base

Knee

Vertical

feed crank

Crossfeed handle

Saddle

Table

Arbor

support

Spindle

Ram type

overarm

6

The plain vertical milling machines (Figure 2.1) are characterized by a spindle

located vertically, parallel to the column face, and mounted in a sliding head that can be

fed up and down by hand or power. Modern vertical milling machines are designed so

the entire head can also swivel to permit working on angular surfaces.

The plain horizintal milling machines (Figure 2.2) column contains the drive

motor and gearing and a fixed position horizontal milling machine spindle. An

adjustable overhead arm containing one or more arbor supports projects forward from

the top of the column. The arm and arbor support are used to stabilize long arbors.

Supports can be moved along the overhead arm to support the arbor where support is

desired depending on the position of the millng cutter or cutters.

2.1.2 Different Operation Of Milling Machine

Figure 2.3: Different operation of miling machine

In peripheral (or slab) milling (Figure 2.3a), the milled surface is generated by

teeth located on the periphery of the cutter body. The axis of cutter rotation is generally

in a plane parallel to the workpiece surface to be machined. Peripheral milling processes

are widely used for the rough or finish cutting of profiled components

In face milling (Figure 2.3b), the cutter is mounted on a spindle having an axis

of rotation perpendicular to the workpiece surface. The milled surface results from the

action of cutting edges located on the periphery and face of the cutter.

(b) Face milling (a) Slab milling (c) End milling

Cutter

Spindle

Arbor

Arbor Spindle

End

mill

Shank

7

The cutter in end milling (Figure 2.3c) generally rotates on an axis vertical to the

workpiece. It can be tilted to machine tapered surfaces. Cutting teeth are located on both

the end face of the cutter and the periphery of the cutter body.

2.2 ALUMINIUM ALLOY

Aluminium alloys are used in many applications due to their wide range of

excellent properties. Since many of these alloys have a high specific static and

dynamic strength they are of great interest for the transportation industry. Consequently

many properties are of importance in each individual application and the alloy

development must focus on maximising one or a combination of properties at the same

time as minimum requirements are fulfilled for the others.

The high-strength aluminum alloy 2519 is used for armor plates applications,

such as in American advanced amphibious assault vehicles (AAAV) . As a new version,

2519A alloy was developed with a superior combination of properties including

mechanical properties, weldability and stress corrosion cracking resistance. It is

acknowledged that the mechanical properties of the armor plate are main factors

influencing its ballistic application. Accordingly, further improving the mechanical

properties, especially which at elevated temperatures, is necessary for expanding the

application fields of 2519A alloy plate.

2.3 MILD STEEL

Mild steel is widely used in engineering because of the low price, good

machining performance and acceptable for many applications. However, the surface

properties suffer because of low surface hardness and poor wear resistance.

Low carbon steel contains approximately 0.05–0.15% carbon and mild steel

contains 0.16–0.29% carbon, therefore it is neither brittle nor ductile. Mild steel has a

relatively low tensile strength, but it is cheap and malleable; surface hardness can be

increased through carburizing.

http://en.wikipedia.org/wiki/Ductile

http://en.wikipedia.org/wiki/Carburization

8

Metal-matrix composites (MMCs) reinforced with hard ceramic particles have

received considerable interest because they can offer improved strength, stiffness and

wear resistance compared to their monolithic counterparts. Steel based composites have

recently attracted great attention for use as wear and corrosion resistant parts in the

chemical and process industry as substitutes for the more expensive cemented carbides

(e.g.WC–Co). However, a poor toughness of the metal matrix composite imposes

restrictions on its application as structural component. On the other hand, wear is a

surface dependent degradation that may be improved by a suitable modification of the

microstructure and/or composition of the near surface region. Hence, instead of the bulk

reinforcement, if a composite layer is developed at the near surface region it would

enhance the wear resistance property significantly without affecting the toughness.

2.4 UNCOATED CARBIDE CUTTING TOOLS

This material usually consists of tungsten carbide or a mixture of tungsten

carbide, titanium, or tantalum carbide in powder form, sintered in a matrix of cobalt or

nickel. As this material is expensive and has low rupture strength it is normally made in

the form of tips which are brazed or clamped on a steel shank. The clamped tips are

generally used as throw away inserts. The two major groups of carbides used for

machining are tungsten carbide and titanium carbide.

2.4.1 Tungsten Carbide

Tungsten carbide (WC) typically consists of tungsten-carbide particles bonded

together in a cobalt matrix. These tools are manufactured using powder-metallurgy

techniques. Tungsten-carbide particles are first combined with cobalt in a mixer,

resulting in a composite material with a cobalt matrix surrounding the carbide particles.

These particles, which are 1 to 5µm in size, are then pressed and sintered into the

desired insert shapes. Tungsten carbides frequently are compounded with titanium

carbide and niobium carbide to impart special properties to the material.

The amount of cobalt present, ranging typically from 6 to 16%, significantly

affects the properties of tungsten-carbide tools. As the cobalt content increases, the

9

strength, hardness and wear resistance of WC decrease, while it toughness increases

because of the toughness of the cobalt. Tungsten-carbide tools generally are used for

cutting steels, cast irons, and abrasive nonferrous materials and largely have replaced

HSS tools because of their better performance.

2.4.2 Titanium Carbide

Titanium carbide (TiC) consists of a nickel-molybdenum matrix. It has higher

wear resistance than tungsten carbide but is not as tough. Titanium carbide is suitable

for machining hard materials and for cutting at speed higher than those appropriate for

tungsten carbide.

2.5 SURFACE ROUGHNESS

In all method of production, all surface has their own characteristics, which

collectively are referred to as surface texture. Surface roughness of a machined product

could affect several of the product’s functional attributes, such as contact causing

surface friction, wearing, light reflection, heat transmission, ability of distributing and

holding a lubricant, coating, and resisting fatigue (Lou & Chen, 1997). Therefore,

surface roughness becomes one of the important quality aspects in end milling products.

Although the description of surface texture in term of well defined and measurable

quantities. Surface roughness generally is described by two methods.

(i) The arithmetic mean value (Ra) is based on the schematic illustration of a

rough surface, as shown below. It is defined as

Ra = a + b + c + d + … (2.1)

n

where all ordinates, a, b, c,…, are absolute values and n is the number of

readings.

10

(ii) The root-mean-square roughness (Rq, formerly identified as RMS) is defined

as

Rq = a2 + b

2 + c

2 + d

2 + … (2.2)

n

Several factors will influence the final surface roughness in a CNC milling

operation. The final surface roughness might be considered as the sum of two

independent effects: 1) the ideal surface roughness is a result of the geometry of tool

and feed rate and 2) the natural surface roughness is a result of the irregularities in the

cutting operation (Boothroyd & Knight, 1989).

Factors such as spindle speed, feed rate, and depth of cut that control the cutting

operation can be setup in advance. However, factors such as tool geometry, tool wear,

chip loads and chip formations, or the material properties of both tool and workpiece are

uncontrolled (Huynh & Fan, 1992).

2.5.1 Measuring Surface Roughness

Typically, instruments called surface profilometers(Mpi Mahr Perthometer) are

used to measure and record surface roughness. A profilometer has a diamond stylus that

travels along a straight line over the surface. The distance that the stylus travels is called

cutoff, which generally range from 0.08 to 25 mm. a cutoff of 0.8 mm is typical for

most engineering applications. The rule of thumb is that the cutoff must be large enough

to include 10 to 15 roughness irregularities, as well as all surface waviness.

In order to obtain better surface roughness, the proper setting of cutting

parameters is crucial before the process takes place. As a starting point for determining

cutting parameters, technologists could use the hands on data tables that are furnished in

machining data handbooks. Lin (1994) suggested that a trail-and-error approach could

be followed in order to obtain the optimal machining conditions for a particular

operation.In order to highlight the roughness, profilometer traces are recorded on an

exaggerated vertical scale. The magnitude of the scale is called gain on the recording

instrument. Thus, the recorded profile is distorted significantly, and the surface appears

11

to be much rougher than it actually is. The recording instrument compensates for any

surface waviness, it indicates only roughness.

Because of the finite radius of the diamond stylus tip, the path of the stylus is

different than the actual surface and the measured roughness is lower. The most

commonly used stylus tip diameter is 10 µm. The smaller the stylus diameter and the

smoother the surface, the closer is the path of the stylus to the actual surface profile.

CHAPTER 3

METHODOLOGY

3.1 INTRODUCTION

Performance of cutting tools is mainly controlled by material properties such as

wear resistance, fracture toughness, and thermal resistance. Wear of cutting edge is

caused mainly by load, friction, and high temperature. Wear mechanism could be

classified as adhesion, abrasion, diffusion, oxidation, and fatigue. High-speed cutting

(HSC) always generates high temperature, which enhances diffusion and oxidation

process of carbide tool. Diffusion process between the chip and the top rake surface of

the cutting edge results in crater wear, and oxidation reactions with the environment

induce scaling of the cutting edge. Diffusion wear is more affected by chemical factors

and the mechanism depends on the chemical properties and the affinity of the tool

material to the workpiece material. Fatigue wear is often a thermo-mechanical

combination, and the fluctuations of temperature, loading and unloading of cutting

forces can lead to cracking and breaking of cutting edges.

In this research, the performance of uncoated carbide cutting tool was studied

experimentally by evaluating the effect of cutting speed, feed, and depth of cut on

surface finish produced. The study was carried out by simultaneously varying the

cutting parameters such as cutting speed, feed, and depth of cut by fitting the value in a

Response Surface Method (RSM). The design of experiment introduced by RSM

significantly reduces the number of experiment

13

Figure 3.1: Procedure flow diagram

METHODOLOGY

Determining all research requirement

LITERATURE REVIEW

Create Aim and Objectives of

research

START

FINISH

MACHINING/ EXPERIMENT

Data Discussion and Conclusion of

Project

NO

YES

PROJECT PRESENTATION

SUBMISSION OF FYP REPORT

RESULT

ANALYSIS

PERFORMANCE OF UNCOATED CUTTING TOOLS WHEN …umpir.ump.edu.my/id/eprint/1836/1/Mohd_Fahmi_Md_Yusuf_(_CD_4948_).pdf · mild steel and 79.55% accuracy for aluminium alloy which reliable

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