CHAPTER 1: INTRODUCTION CHAPTER 2: LITERATURE REVIEW CHAPTER 3: METHODOLOGY 30

v TABLE OF CONTENTS Abstract v Abstrak v Dedication v Acknowledgement vi Table of Content vii List of Tables ix List of Figures x

1.0 CHAPTER 1: INTRODUCTION

1 1.1 Background 1 1.2 Problem Statement 2

1.3 Objective of Study

3 1.4 Scope of Study 4

2.0 CHAPTER 2: LITERATURE REVIEW

5

2.1 Principles of Laser Cutting

5 2.2 Types of Laser Cutting 8 2.2.1 Laser Fusion Cutting 8 2.2.2 Laser Oxygen Cutting 9 2.2.3 Laser Vaporization Cutting 10 2.2.4 CO 2 Laser Cutting 11 2.3 Laser Cutting on Thermoplastic 12 2.3.1 Polypropylene PP 14 2.3.2 Applications of PP 15 2.3.3 Laser processing on PP plastic sheet 16 2.4 Machine Used 16 2.5 Parameters for CO 2 Laser Cutting 17 2.5.1 Focal Length of the Lens 17 vi 2.5.2 Cutting Speed 19 2.5.3 Laser power 20 2.6. Cutting quality 21 2.6.1 Surface Roughness 21 2.6.2 Basic rules affecting cut quality 23 2.6.2.1 The edge finish 23 2.6.2.2 Thickness of material 25 2.6.2.3 Power variations 25 2.6.2.4 Beam quality 25 2.6.2.5 High-energy density beams 25 2.6.2.6 Speed of cut 25 2.6.2.7 Exhaust of smoke and vapor 26 2.7 Considerations in laser cutting 26 2.7.1 Primary Considerations in Laser Processing 26 2.7.1.1 Absorption of material 27 2.7.1.2 Thermal diffusity 27 2.7.1.3 Reaction temperature 27 2.7.2 Secondary considerations in laser cutting 27 2.7.2.1 Heat-affected zone 27 2.7.2.2 Smoke or debris 28 2.7.2.3 Burr or dross on edge 28 2.7.2.4 Thermal expansion 28 2.7.2.5 Dissimilar materials 28 2.7.2.6 Tolerances 29

3.0 CHAPTER 3: METHODOLOGY 30

3.1 Topic Selection 30 3.2 Material Selection 31 3.3 Design of experiment 31 3.4 Full Factorial Design of Experiment 33 3.4.1 Analysis of Full Factorial Design of Experiment 34 vii 3.5 Methodology for DOE 34 3.5.1 Define the Objective 34 3.5.2 Identification of Design Factor and Level 34 3.5.3 Identify suitable Response Variable 35 3.5.4 Preparation of Experiment 35 3.5.5 Performing the trial Experiment and Actual experiment 36 3.5.6 Analyze and interpret results of experiment run 37 3.6 Project Flow Chart 39

4.0 CHAPTER 4: DISCUSSION