ABSTRACT

This work presents the assessment of aluminum alloy 356 with cow horn composite as a machining material. In other to enable manufacturers to maximize their gains from utilizing hard turning, an accurate model of the process must be constructed. In course of this work, a mathematical model was developed to relate the material removal rate (MRR), tool wear ratio (TWR) and surface roughness (Ra) to machining parameters (feed rate, depth of cut and cutting speed). To achieve this, A356/cow horn particles (CHp) composite was adopted from Ochieze, 2017. A design of experiment was generated using the optimal custom design techniques in Response Surface Methodology (RSM) from the Design Expert Software 11.0. after the optimization, the results from the ANOVA tables of the tool wear, surface roughness and material removal rate show some models are significant with the probability value (P-value) 0.0203, 0.0412. The results of the analysis of variance (ANOVA) indicate that the proposed mathematical models, can adequately describe the performance within the limits of the factors being studied. It was also observed that the cutting speed plays a dominant role in tool wear rate (TWR) and surface roughness (Ra) while the depth of cut has the least influence on the tool wear rate (TWR) and surface roughness (Ra). Finally, the good surface quality with the minimum tool wear can be achieved when cutting speed and feed rate are set nearer to their middle level (900rpm, 0.25 rev/mm) and depth of cut is at high level of the experimental range (1.5mm). In summary, in order to enable manufacturers to maximize their gains in utilizing hard turning of AACHC, they should employ the optimized cutting parameters.

 TABLE OF CONTENTS

Cover page                                                                                                                  PAGE

Title page                                                                                                                    i

Certification                                                                                                                ii

Declaration                                                                                                                  iii

Dedication                                                                                                                  iv

Acknowledgement                                                                                                      v

Table of Contents                                                                                                       vi

List of Tables                                                                                                              ix

List of Figures                                                                                                             x

Nomenclatures                                                                                                            xi

Abstract                                                                                                                      xii

CHAPTER 1: INTRODUCTION

1.1      Background of the Study                                                                                 1

1.2      Statement of Problem                                                                                       3

1.3      Aim and Objectives of Study                                                                          3

1.4      Scope of Study                                                                                                 4

1.5      Justification of the Study                                                                                 4

CHAPTER 2: LITERATURE REVIEW

2.1      Machining Parameters and Their Effects                                                         6

2.1.1   Feed Rate                                                                                                         6

2.1.2   Cutting Speed                                                                                                  17

2.1.3   Depth of Cut                                                                                                    23

2.2      Summary of Review                                                                                         41

2.3      Research Gap                                                                                                   42

CHAPTER 3: MATERIALS AND METHODS

3.1      Materials                                                                                                           43

3.2           Methods                                                                                                           43

3.2.1   Experimental Procedure                                                                                   43

3.2.2     Machining operation                                                                                         44

3.3      Design of Experiment                                                                                      45

CHAPTER 4: RESULTS AND DISCUSSION

4.1      Machining Operation using Design of Experiment (DOE)                              47

4.1.1   Surface Roughness                                                                                           52

4.1.2   Material Removal Rate                                                                                     56

4.1.3   Tool Wear                                                                                                         60

4.2      Effect of The Machining Parameters on the Performance Measures               64

4.2.1   Effect of feed rate on surface roughness                                                         64

4.2.2   Effect of feed rate on material removal rate                                                    64

4.2.3   Effect of feed rate on tool wear                                                                       65

4.2.4   Effect of cutting speed on surface roughness                                                  66

4.2.5   Effect of cutting speed on material removal rate                                             66

4.2.6   Effect of cutting speed on tool wear                                                               67

4.2.7   Effect of depth of cut on surface roughness                                                    68

4.2.8   Effect of depth of cut on material removal rate                                               68

4.2.9   Effect of depth of cut on tool wear                                                                 69

4.3      Optimization using RSM                                                                                  70

CHAPTER 5: CONCLUSION AND RECOMMENDATIONS

5.1      Conclusion                                                                                                        71

5.2      Recommendations                                                                                            72

5.3      Contributions to Knowledge                                                                            73

References                                                                                                                  74

Appendix                                                                                                                    80

 

 

 

 

 

 

 

 

 

 

 

 

 

LIST OF TABLES

                                                                                                                        PAGE

3.1       Independent process variable and design level                                              45

3.2       Machining design matrix and measured responses                                         45

4.1       Summary data table of the actual design after experiment                            47

4.2       Build Information                                                                                           48

4.3       Independent process variable and design level                                              48

4.4       Responses                                                                                                       48

4.5       Model terms of build information                                                                  49

4.6       Model terms of surface roughness                                                                  52

4.7       Fit statistics of surface roughness                                                                   52

4.8       Model comparison statistics of surface roughness                                          52

4.9       Coefficients in terms of coded factors of surface roughness                         53

4.10     Model terms of MRR                                                                                     56

4.11     Fit statistics of MRR                                                                                      56

4.12     Model comparison statistics of MRR                                                             56

4.13     Coefficients in terms of coded factors of MRR                                             57

4.14     Model terms of tool wear                                                                               60

4.15     Fit statistics of tool wear                                                                                60

4.16     Model comparison statistics of tool wear                                                       60

4.17     Coefficients in terms of coded factors of tool wear                                       61

 

 

 

LIST OF FIGURES

                                                                                                                        PAGE

4.1       Fraction of Design Space                                                                                49

4.2       Interaction between the factors and the response                                          50

4.3       Perturbation Plot                                                                                             51

4.4       3D graph for surface roughness                                                                      54

4.5       Graph of predicted values and actual values of surface roughness                55

4.6       3D graph for material removal rate                                                                 58

4.7       Graph of predicted values and actual values of material removal rate           59

4.8       3D graph for tool wear                                                                                   62

4.9       Graph of predicted values and actual values of tool wear                             63

4.10     Effect of feed rate on surface roughness                                                        64

4.11     Effect of feed rate on material removal rate                                                   65

4.12     Effect of feed rate on tool wear                                                                     65

4.13     Effect of cutting speed on surface roughness                                                66

4.14     Effect of cutting speed on material removal rate                                           67

4.15     Effect of cutting speed on tool wear                                                              67

4.16     Effect of depth of cut on surface roughness                                                  68

4.17     Effect of depth of cut on material removal rate                                             69

4.18     Effect of depth of cut on tool wear                                                                69

4.19     Numerical optimization                                                                                   70

 

 

 

 

 

NOMENCLATURE

AACHC          Aluminum Alloy Cow-horn Composite

AMMC           Aluminum Metal Matrix Composites

BBD                Box-Behnken Design

BUE                Built-up Edge

CBN                Cubic Boron Nitride

CNC                Computer Numerical Control

CS                   Cutting Speed

CVD               Chemical Vapor Deposition Diamond

DC                  Depth of Cut

DOE                Design of Experiment

FR                   Feed Rate

HSS                 High-Speed Steel

MMC              Metal Matrix Composites

MRR               Material Removal Rate

OCD               Optimal Custom Design

PCD                Poly Crystalline Diamond

Ra                    Surface Roughness

RSM                Response Surface Methodology

TWR               Tool Wear Rate