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EFFECT OF CUTTING PARAMETERS ON THE SURFACE INTEGRITY OF GROUND AISI 1148 STEEL

MOHD ROZAIMI BIN ISMAIL

A project report submitted in partial fulfillment of the requirements for the award of the degree of Master of Engineering

(Mechanical – Advanced Manufacturing Technology)

Faculty of Mechanical Engineering Universiti Teknologi Malaysia

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ACKNOWLEDGEMENT

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ABSTRACT

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ABSTRAK

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vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS AND SYMBOLS xvi

LIST OF APPENDICES xvii

1 INTRODUCTION

1.1 Background 1

1.2 Problem Statement 2

1.3 Objectives of Study 3

1.4 Significance of the Study 4

1.5 Scopes of Study 4

1.6 Organization of the Project Report 5

2 LITERATURE REVIEW

2.1 Introduction 6

2.2 Surface Grinding 7

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2.3 Mechanics of Grinding 16

2.3.1 Spesific Heat Energy 19

2.3.2 Temperature During Grinding 22

2.3.3 Grinding Wheel Wear 23

2.3.4 Ductile Mode Machining of Hard and

Brittle Material 26

2.4 Metal Alloys: Structure and Heat Treatment 28

2.4.1 Introduction 28

2.4.2 Structures of Alloys 29

2.4.3 Phase Diagram 33

2.4.4 The Iron Carbon System 38

2.5 Heat Treatment of Ferrous Alloys 41

2.5.1 Time Temperature Transformation Diagram 45

2.5.2 Martensite 47

2.5.3 Continuous Cooling Transformation

Diagram 50

2.5.4 Tempered Martensite 53

2.6 Surface Roughness Measurement 57

2.6.1 Surface Structure and Integrity 57 2.6.2 Surface Texture and Surface Roughness 59 2.7 Rockwell and Superficial Hardness Test 60

3 RESEARCH METHODOLOGY

3.1 Component/Workpiece 62

3.2 Grinding Wheel 62

3.3 Grinding Process 63

3.4 Machine Tool 63

3.5 Measuring Equipments 66

3.6 Design of Experiment 67

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4 RESULT AND DISCUSSION

4.1 Result 71

4.1.1 Response 1 : Surface Roughness 73 4.1.2 Response 2 : Surface Hardness 79 4.2 Discussion

4.2.1 Surface Roughness 84

4.2.2 Surface Hardness / Superficial Hardness 85

5 CONCLUSION AND RECOMMENDATIONS 89

REFERRENCES 91

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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Hardness value of abrasive material used in grinding

wheel (I. D. Marinescu et. al., 2007) 10 2.2 Marking system for conventional grinding wheels as

defined by ANSI Standard (I. D. Marinescu et. al., 2007) 14 2.3 Approximation of the fraction of heat (R) going to

the workpiece (S. Malkin, 1984) 23

3.1 Specifications of Grinding Machine 63

3.2 Experimental design table 68

3.3 Experimental design matrix 69

4.1 The grinding operation parameters and the value of

surface roughness and surface hardness obtain 72

4.2 ANOVA for Response 1: Surface Roughness 73

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Schematic illustration of various surface grinding

operation (a) Horizontal- spindle surface grinder: traverse grinding (b) Horizontal-spindle surface grinder: plunge

grinding (S. Malkin, 1984) 8

2.2 Schematic illustration of a horizontal spindle surface

grinder (S. Malkin, 1984) 8

2.3 Typical structure of grinding wheel

(I. D. Marinescu et. al., 2007) 13

2.4 Some of the standard wheel shape:

(I. D. Marinescu et. al., 2007) 15

2.5 A line diagram showing (a) the basic scheme

of the surface grinding operation similar to that of the up milling operation and (b) the cutting action of active grain that are randomly distributed in the periphery of bonded abrasive wheel .(V. C. Venkatesh et. al., 2006) 16 2.6 (a) Relationship between the cutting force and the wheel

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grinding operation .(V. C. Venkatesh et. al., 2006) 17 2.7 A schematic of a horizontal surface grinding operation

showing an individual undeformed chip and grinding

parameters .(V. C. Venkatesh et. al., 2006) 18 2.8 Shows size effect relationship between chip thickness

and resisting shear stress of a carbon steel modified by Taniguchi with the addition of tension test.

(V. C. Venkatesh et. al., 2006) 21

2.9 Radial volumetric wheel wear versus accumulated metal removed for an external cylindrical grinding plunge

grinding operation .(V. C. Venkatesh et. al., 2006) 24 2.10 A schematic illustration of the wheel wear mechanism :

(A) Attritious wear (B) Grain Fracture (C) bond fracture (D) Intrefacial grain bond fracture .

(V. C. Venkatesh et. al., 2006) 25

2.11 Conventional machining processes versus the

nanogrinding process 27

2.12 Cross section of gear teeth showing induction hardened

surfaced (W. D. Calister, 2004) 28

2.13 (a) Schematic illustration of grain, grain boundaries, and particle dispersed throughout the structure of two phase system. (b) Schematic illustration of a two phase system consisting of two sets of grain: dark and light

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2.14 (a) Cooling curve for the solidification of pure metal. Note that freezing take place at a constant temperature, The latent heat of solidification is given off. (b) Change in density during the cooling of pure metal

(W. D. Calister, 2004) 34

2.15 Phase diagram for nickel copper alloy obtained at a

slow rate of solidification . (W. D. Calister, 2004) 36 2.16 The lead-tin phase diagram. (W. D. Calister, 2004) 37

2.17 The iron –iron carbide phase diagram. 39

2.18 The unit cells for (a) austenite,

(b) ferrite, and (c) martensite 40

2.19 Microstructure of eutectoid steel. Spheroidite is formed by tempering the steel at 7000C. Magnification 1000X

(W. D. Calister, 2004) 42

2.20 (a) Hardness of martensite as a function of carbon content, (b) Micrograph of martensite containing 0.8% carbon. 43 2.21 Hardness of tempered martensite as a function

of tempering time for 1080 steel. (W. D. Calister, 2004) 45 2.22 (a) Austenite to pearlite transformation of iron

carbon alloy as a function of time and temperature. (b) Isothermal transformation diagram obtained from (a) for a transformation temperature of 6750C.

(c) Microstructures obtained for a eutectoid iron carbon alloy as a function of cooling rate. (W. D. Calister, 2004) 46 2.23 Photomicrograph of a steel having a spheroidite

microstructure. (W. D. Calister, 2004) 47 2.24 The body centered tetragonal unit cell for martensitic

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occupied by carbon atoms (crosses). For this tetragonal

unit cell.(W. D. Calister, 2004) 48

2.25 The body centered hexagonal unit cell for martensitic steel showing iron atoms (circles) and sites that may be

occupied by carbon atoms (crosses). For this hexaonal

unit cell (W. D.Calister, 2004) 49

2.26 Superimposition of isothermal and continuous cooling transformation diagram for eutectoid iron carbon alloy.

(W. D. Calister, 2004) 50

2.27 Moderately rapid and slow cooling curves superimposed on a continuous cooling transformation diagram

for a eutectoidiron – carbon alloy (W. D. Calister, 2004) 52 2.28 Continuous cooling transformation diagram for a eutectoid

iron-carbon alloy and superimposed cooling curves

(W. D. Calister, 2004) 52

2.29 Electron micrograph of tempered martensite

(W. D. Calister, 2004) 55

2.30 Tensile and yield strength and ductility (%AR) versus tempering temperature for an oil quenched alloy steel

(type 4340) (T. Tawakoli et. al., 2007) 55 2.31 The hardness of the alloy steel in tempering temperature

time (T. Tawakoli et. al., 2007) 56

2.32 Principles of the Rockwell and Rockwell superficial

hardness tests (A. Nayar, 2005) 60

3.1 The grinding machine 65

3.2 Surface roughness tester machines 66

3.3 Hardness tester machine 67

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4.3 Predicted vs Actual (Surface Roughness) 76

4.4 Interaction graph – cross feed and speed

(Surface Roughness) 76

4.5 Interaction graph- coolant and speed (Surface Roughness) 77 4.6 Interaction graph – speed and infeed (Surface Roughness) 77 4.7 Interaction graph – coolant and cross feed

(Surface Roughness) 78

4.8 Interaction graph – speed and infeed (Surface Roughness) 78

4.9 Normal plot residual (Surface Hardness) 81

4.10 Residual vs Predicted (Surface Hardness) 81

4.11 Predicted vs Actual (Surface Hardness) 82

4.12 Residual vs speed (Surface Hardness) 82

4.13 Interaction graph – Cross feed and speed

(Surface Hardness) 83

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LIST OF ABBREVIATIONS AND SYMBOLS

Pg - Proportion of abrasive grains in the total wheel volume Pb - Proportion of bond material

Pp - Proportion of pores (air gaps) ANOVA - Analysis of variance

t - Chip thickness

u - Specific grinding energy

Ft - Tangential grinding force FH - Horizontal grinding force FV - Vertical grinding force

V - Cutting speed

v - Workpiece speed

d - Infeed

b - Width of the cut

F - Wheel speed

D - Wheel diameter

- Mean surface temperature

pC - Volume specific heat

Vw - Volume remove

Vs - Volume of the wheel wear

TTT - Time-Temperature-Transformation FCC - Face centered cubic

BCC - Body centered cubic

CCT - Continuous cooling transformation

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S - Scale unit, specific to the Rockwell hardness

HB - Hardness Brinnel

HV - Hardness Vickers

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LIST OF APPENDICES

APPENDIX TITLE PAGE

A1 Design Actual 93

A2 Design Summary 94

A3 Effect for Response 1: Surface Roughness 95

A4 ANOVA for Response 1 : Surface Roughness 96

A5 Diagnostic for Response 1: Surface Roughness 102 A6 Model Graph for Interactions : Surface Roughness 105

A7 Effect for Response 2: Surface Hardness 108

A8 ANOVA for Response 2 : Surface Hardness 109

A9 Diagnostic for Response 2: Surface Hardness 113

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CHAPTER 1

INTRODUCTION

1.1 Background

Grinding is a complex metal cutting process, which for many centuries has been perfected via study and complex analytical approach. It is well known that this machining process consume more energies compare to another machining methods. Generally, grinding process is closely related to the main objective as the best cutting method to produce a dimensionally and geometrically accurate workpiece. The relationship between cutting condition and the surface finish of the workpiece has been establish and verified through series of studies.

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hardened are mostly characterized by compressive residual stresses in the surface layer (E. Brinksmeler et al, 1996). An attempt also has been made by O. Zurita et al (2002) to discover the influence of the cutting parameters on the superficial hardening of AISI 1045. She comes out with a conclusion that the increasing value of parameters lead to the higher superficial hardening on the workpiece. Other study (P. Krajnik, 2005), design the grinding factors based upon surface methodology or classically design of experiment. Superficial hardness is closely related to the amount of the residual stresses on the material surface during machining. Y. Matsumoto (1991) demonstrates that the residual stresses are mainly by; (1) martensite transformation near the surface (2) the plastic flow of the material on the surface and adjacent areas due to thermal stresses cause by heat generated during the process (3) plastic deformation due to the cutting forces of the grain on the surface of workpiece.

In spite of that, a question related to the optimum grinding cutting parameters which can induced superficial hardening together with great surface roughness were never being answered.

Therefore, this study work have been propose in order to determine the optimum parameter and co relation between good surface roughness and the superficial hardness of the workpiece.

1.2 Problem Statement

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third was machine characteristic, which is spindle abd table stiffness, damping and dynamic characteristic. The fourth is operating condition which would be the concern parameters in this study include wheel speed, feed, depth of cut and coolant flow rate.

Several information has been extracted from previous study. a carbon content is crucial to induce the superficial hardening process to take place in grinding. It is also suggested that the severe cutting condition will assist in martensite formation in microstructure level of workpiece. Workpiece with high carbon content will be applied in this study. In addition, a good surface finish is also a response to the experiment done. How the cutting parameters influence the value of the surface roughness and the surface hardness will be determine through the study work. Furthermore, what are the optimum value to achieve the best for both response.

1.3 Objective of the Study

The study was carried out to investigate the effect of the operating condition which are wheel speed, feed, depth of cut and coolant flow rate upon surface integrity of the workpiece (AISI 1148). The surface integrity involve are surface roughness and superficial hardness of the workpiece.

The objectives of this study are:

I. To investigate the effect of the operating condition which are workpiece speed, infeed, crossfeed, coolant flow rate on the surface roughness and surface hardness of ground AISI 1148 steel.

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1.4 Significance of the Study

The industries request upon good surface finish component with high hardness has pushed the researchers to come out with the optimum condition in grinding technology. The best value which can compensate both surface roughness and surface hardness must be determine for every metal and non metal. A grind process not yet being closely discovered and understood. This study will contribute to the knowledge of understanding the surface roughness and possibility to induce the superficial hardening by together with good surface finish in component. It will also indirectly contribute to the industry in term of cutting the cost of hardening process which can be integrated in the operation line.

1.5 Scope of the Study

This study is limited within the scope listed;

I. AISI 1148 steel will employed as a workpiece material.

II. Surface roughness tester machine brand Mitutoyo SJ-400 will be employed.

III. Grinding wheel aluminium oxide with the marking system A60M5V will be employed.

IV. Vickers microhardness tests will be employed to determine HV values of the workpiece.

V. The experiments will be limited to surface grinding

VI. The wheel and machine characteristic are not factors to be considered in this experiment.

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1.6 Organization of Project Report

References

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