Preliminary Investigation Of Plastics Joining Process.

PRELIMINARY INVESTIGATION OF PLASTICS

JOINING PROCESS

SITI NOORAISHAH BINTI ELIES

B051010171

UNIVERSITI TEKNIKAL MALAYSIA MELAKA 2013

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

PRELIMINARY INVESTIGATION OF PLASTICS JOINING

PROCESS

This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Manufacturing Process) (Hons.)

by

SITI NOORAISHAH BINTI ELIES B051010171

900409015894

FACULTY OF MANUFACTURING ENGINEERING 2013

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: Preliminary Investigation of Plastics Joining Process

SESI PENGAJIAN: 2012/13 Semester 2 Saya SITI NOORAISHAH BINTI ELIES

mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut: 1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.

2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja dengan izin penulis.

3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan

pertukaran antara institusi pengajian tinggi. 4. **Sila tandakan (_/)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysiasebagaimana yang termaktub dalam AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)

Alamat Tetap: NO. 1 Jalan KM 2, Taman Kota Mas,

81900 Kota Tinggi, Johor.

Tarikh: _________________________

Disahkan oleh:

Cop Rasmi:

Tarikh: _______________________

** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai SULIT atau TERHAD.

DECLARATION

I hereby, declared this report entitled “Preliminary Investigation of Plastics Joining Process” is the results of my own research except as cited in references.

Signature :

Author’s Name : Siti Nooraishah Binti Elies

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 (Manufacturing Process) (Hons.). The member of the supervisory committee is as follow:

……… (Project Supervisor)

i

ABSTRAK

Kajian awal terhadap proses gabungan plastik dengan menggunakan laser telah dijalankan ke atas botol plastik terpakai (polietilena berketumpatan tinggi, HDPE) yang mempunyai purata ketebalan 1.5 mm. Jenis gabungan yang telah dihasilkan ialah gabungan tindan bagi memdapatkan luas permukaan yang maksima semasa proses penggabungan. Plastik ini digunakan semula untuk mengurangkan kadar buangan sisa pepejal dalam masa yang sama mengekalkan sifat dan ciri-ciri sesuatu bahan tersebut kerana pemprosesan semula hanya akan mengurankan sifat bahan. Tiada tindakbalas dan sentuhan secara langsung terlibat semasa pemprosesan laser. Dengan itu, kerosakan mata alat dan getaran pada mesin dapat dielakkan. Mesin pemotong laser karbon dioksida (Helius Hybrid 2513) telah digunakan untuk proses gabungan menggunakan laser. Proses parameter yang telah dipilih hasil daripada eksperimen OFAT ialah kuasa laser, kelajuan laser dan tekanan gas. Eksperimen ini dijalankan dengan menggunakan kaedah faktorial penuh untuk merekabentuk eksperimen bagi mendapatkan gabungan parameter yang optimum. Eksperimen ini melibatkan dua proses dalam satu masa yang sama iaitu proses gabungan dan proses pemotongan. Hasil kajian membuktikan bahawa mesin laser pemotong telah berjaya menggabungkan dua kepingan plastik hasil daripada haba yang dihasilkan oleh laser. Kualiti dan analisis bagi setiap gabungan yang terhasil telah dilakukan dengan pemeriksaan visual dan ujian lenturan. Hasil analisa menunjukkan bahawa gabungan parameter yang baik dan tindak balas yang optimum dapat dihasilkan daripada gabungan parameter pada peringkat yang lebih tinggi.

ii

ABSTRACT

A preliminary investigation on plastics joining process by laser on waste plastics (HDPE) with average thickness 1.5mm is carried out. Stack joining is performed on the plastic in order to obtain maximum joining surface area. The plastic is re-used in order to minimize rate of solid waste also to maintain the material’s properties since re-processing will just decrease it. Furthermore, indirect contact between laser beam and material has resulting little to no reaction forces imparted upon the material in the same time eliminate tool wear, material damage and machine vibration. Process parameters that have been chosen in this study is based on OFAT experiment which are laser power, travel speed and gas pressure. Full factorial method of parameter design is used as design of experiment (D.O.E) technique to obtain optimal process parameters. The experimental is performed by simultaneous process of joining and cutting. The machine used was Helius Hybrid 2513 Laser Cutting Machine. Results show that Laser Cutting machine has successfully joined the plastic. Quality and performance analysis of the join are performed by visual inspection and flexural test. From analysis, it shows that higher level has produced optimum responses.

iii

DEDICATION

iv

ACKNOWLEDGEMENT

With the name of Allah, I would like to thank Him for giving me this opportunity to complete this work. Million thanks to my parents and family for their infinite support all this while. They had scarified a lot especially in financial, time and moral support. Very special thanks to my supervisor, Associate Professor Ir. Dr. Sivarao Subramonian for guiding and helping me in conducting this research from the very beginning till the end. Your endless guidance and supports even in financial are the backbone of this work. Thank you for your kindness and patient for guiding me and give me loads of additional knowledge and information throughout this project. Besides that, lot of thanks also goes to my fellow friends who helping me days and night. Special thanks dedicated to technicians and FKP staff for their consideration and help throughout the year. Last but not least, I would like to thank to the librarian of UTeM’s library and all people that involve either direct or indirectly in this study. I really appreciated your cooperation. Only God can repay all the kindness given to me.

v

TABLE OF CONTENT

Abstrak i

Abstract ii

Acknowledgement iii

Table of Content iv

List of Figures vii

List of Tables viii

List of Abbreviations, Symbols, Specialized Nomenclature ix

CHAPTER 1: INTRODUCTION 1

1.1 Project Background 1

1.2 Problem Statement 3

1.3 Scope of Project 4

1.4 Objectives 5

1.5 Theory 6

1.5.1 Laser Processing Overview 6

1.5.2 Definition of Laser 8

1.5.3 The Work Process of Laser 8

1.5.4 Laser Properties 10

1.5.5 Types of Laser 12

1.5.6 Laser Machining 14

1.5.7 Laser Processing 17

1.5.8 Types of Parameters 18

1.6 Materials 21

1.6.1 Metals 22

1.6.2 Ceramics 22

1.6.3 Polymers 23

vi

1.7 Plastics Joining Processes 25

1.7.1 Fusion Welding 26

1.7.2 Types of Joint 27

CHAPTER 2: LITERATURE REVIEW 28

2.1 Laser Welding of Non-Metallic Material 28

2.1.1 Thermoplastics Material 28

CHAPTER 3: METHODOLOGY 35

3.1 Research Methodology Flowchart 35

3.2 Material Selection 37

3.3 Investigation of Process Parameters 38

3.4 Design Parameters Identification 38

3.5 Design of Experiment (DOE) 39

3.5.1 Design of Experiment (DOE) Matrix 40

3.5.2 Factorial Design 41

3.5.3 Level 41

3.5.4 Variable 41

3.5.5 Parameter Involved 42

3.6 Experimental Work 43

3.7 Experiment Setup 44

3.8 Observation & Evaluation 48

3.8.1 Non-destructive Test 48

3.8.2 Destructive Test 49

3.9 Result 52

3.10 Discussion/Conclusion 52

CHAPTER 4: RESULT & DISCUSSION 53

4.1 Joined Produced 53

vii

4.3 Flexural Result 65

4.4 Defects 70

4.5 Effect of Travel Speed and Laser Power on Joining Process 71

4.6 Effect of Gas Pressure on Joining Process 72

CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS 73

REFERENCES 75

APPENDICES 79

A 79

B 80

viii

LIST OF TABLES

2.1 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 4.4 4.5 4.6 4.7

Summarizing overview of carbon black concentration, optical penetration depth and bridged gap for the investigated flat samples while applying contour welding (U. A. Russek et al., 2003)

D.O.E Matrix for experimental work Parameters and Level

Basic specifications of the LVD Helius Hybrid 2513 Laser Cutting Machine

D.O.E Matrix

Specimen dimension

Semi crystalline and amorphous structure

Length measurement and the percentage of error (% error) Width measurement and the percentage of error (% error) Thickness dimension and the percentage of error (% error)

Maximum force, flexural strength and flexural strain of the joined plastic

Close view of failed specimens at join area under Stereo Digital Imaging Microscopy Defects 33 40 42 43 47 51 54 58 60 63 65 66 70

ix

LIST OF FIGURES

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 2.1 2.2 2.3

Classification of Laser Material Processing Flow Chart (Majumdar J. D. And Manna I., 2003)

Simple Atom Model Photon Simulation Photon Amplification

Comparison of Monochromatic Light between Fluorescent Light and Laser (Wasikowski J., 2003)

Comparison of Coherency between Normal Light and Laser (Wasikowski J., 2003)

Comparison of Radiance of Light Bulb and Laser Beam (Wasikowski J., 2003)

Schematic of One, Two and Three-Dimensional Laser Machining (Wasikowski J., 2003)

Laser Cutting Head (TRUMPF, 2000)

Focal positon (Manual of Helius 2513 Laser Machine, 2000) Stand off Distance (Manual of Helius 2513 Laser Machine, 2000) Properties of polymers

Structures of thermoplastics Joining processes

Basic weld joints

Averaged weld failure force and visual ratings for each of factor level combinations. Each colour code represents different level of visual appearance (James D. Van de Ven and Arthur G. Erdman, 2007)

Weld width as a function of velocity and laser power (James D. Van de Ven and Arthur G. Erdman, 2007)

Weld strength as a function of velocity and laser power (James D.

7 8 10 10 11 11 12 14 16 21 21 23 24 26 27 30 31 31

x 2.4 2.5 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 (a) 3.8 (b) 3.9 3.10 3.11 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Van de Ven and Arthur G. Erdman, 2007)

Main effects plot for S/N ratios (B. Acherjee et al., 2010) Percentage distribution of each process parameter to weld strength (B. Acherjee et al., 2010)

Methodology Flowchart HDPE engine oil bottle

Helius Hybrid 2513 Laser Cutting Machine Flow chart for experimental setup

Drawing of specimen to be cut and join

Screen display where parameter values were change Laser beam movement direction

Venire Calliper

Stereo Digital Imaging Microscopy Loading diagram

Universal Testing Machine Flexural test on joined plastic

Image of two plastic sheets before subjected to laser joining process

Image of two plastic sheets after subjected to laser joining process

Close view of joining area on specimen produced from experiment number 7

Close view of ‘frame-line’ on inside part of specimen from experiment number 1

Three points at which the length were observed Three points at which the width were observed

Points at which the thickness dimensions were observed Maximum Force versus Number of Experiment

Flexural Strength versus Number of Experiment Flexural Strain versus Number of Experiment

34 34 36 37 43 44 45 46 48 49 49 50 50 52 55 55 55 56 57 59 62 67 68 69

xi

LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED

NOMENCLATURE

% - percent

& - and

” - inch

< - less than > - more than

± - plus minus

≈ - almost equal to

® - Right

3D - three dimensional

A - Absorption

angstroms - measure of length, 1 angstrom= 10E-10m ANOVA - Analysis Of Variance

ANSI - American National Standard Institute cm - centimetre

CO2 - Carbon Dioxide Gas

CVL - Copper Vapour

Cw - clock wise

CW - Continuous Wave

D - Diameter

D.O.E - Design of Experiment

DC - Duty Cycle

DIN - Deutsche Industry Norm E - Energy per Pulse

e.g. - example EB - Electron Beam

xii etc. - Exedra/ and others

F - Frequency

F.D. - Focal Distance

FKP - Faculty of Manufacturing Engineering (Fakulti Kejuruteraan Pembuatan)

GP - Gated Pulse

H2 - Hydrogen Gas

HAZ - Heat Affected Zone

He - Helium Gas

Hz - Hertz

in. - inch

IPTA - The Public Institution of Higher Learning (Institut Pengajian Tinggi Awam)

ISO - International Organization for Standardization

J - Joule

K - Kelvin

k - kilo

kg - Kilogram

L - Length

LASER - Light Amplification by Stimulated Emission of Radiation

m - meter

mA - mili Ampere

MB - Mega Byte

Mil - 1 mil = 0.254 mm mJ - mili Joule

mm - millimetre MPa Mega Pascal

N Nominal value

N2 - Nitrogen Gas

NC - Numerical Control

xiii

Nm - Nanometer

No/Num - Number

o

- Degree

ø - Diameter

O2 - Oxygen Gas

p - Pressure

P - Power

Pa - average power Pp - peak power

ps - Pico second

PSM - Bachelors Degree Project (Projek Sarjana Muda)

R - Radius

R - Reflectivity RF - radio-frequency

s - Seconds

SOD - Stand Off Distance STD. Standard

T - Transmissivity

t - Thickness

TEA - Transversely Excited Atmosphere Pressure

UTeM - Malaysia Melaka Technical University (Universiti Teknikal Malaysia Melaka)

UV - Ultraviolet

V - Volt

W - Watt

WJ - Water jet

- Wave length symbol

m - micrometer

Σ - Total

1

Chapter 1 is basically includes the entire report content starting from Project Background up to Plastics Joining Processes. Related information regarding laser processing is included in this chapter.

1.1 Project Background

Laser machining is widely known for cutting almost any materials. The highly focus, high-density energy source melts and evaporates portions of the workpiece in a controlled manner. Laser cutting which is one laser machining process could be referred as a material removal process accomplished by laser material interaction. Besides machining, laser also is been used in processing such as welding. Laser welding is a non-contact process and involves localized heat treating of materials to modify the surface mechanical and tribological properties (Kalpakjian, 2010).

Used products with plastics based are usually recycled. When the material is recycled, the properties of the material will not remain the same. Usually the properties are reduced and qualities of secondary products are low. Instead of re-melt or recycle the material, the used product is reused. In addition, due to high investment cost needed to setup a laser machine, optimization of existing laser cutting machine is the main goal of this study. For experimental, laser joining process will be performed by laser cutting machine instead of laser welding machine. In laser processing, the controllable process parameters are quite same for any process.

INTRODUCTION

2

The challenge in conducting this study is to identify the most suitable parameters to be applied in laser welding. This preliminary investigation will determined the capability of CO_{2 laser to produce join between materials by varying}

some of process parameters. A laser cutting machine with rated power 3kW is used in this experimentation work.

The join is evaluated through visual inspection and destructive tests. Throughout this study, CO_{2 laser cutting machine has proved its ability to melt and}

form join at the interface of the plastic sheets and pass minimum requirement in mechanical destructive test.

3

1.2 Problem Statement

Huge wastage of plastic bottle has become a big problem faced by the country. In average, one Malaysian citizen has produced abut 0.8kg waste per day. It is expected that in 2020, 30 000 tonne waste will be produced since only 5% of the total waste is recycled. This is a hug number for a small country like Malaysia. Due to this problem, waste plastic (HDPE) is chosen as the main material to be used in experimentation. The plastic is used in order to maintain its properties since re-meting will just reduce it. Besides, high cost is required to setup recycling equipment.

The challenge in this study is to determine which parameters that is suitable to be manipulated so that two plastic sheets can be joined together to increase its use. Since laser cutting and laser welding have almost same parameters, the requirement to buy a new laser welding machine can be eliminated because there is high possibility that a laser cutting machine can do joining without changing any part of the machine. Even though the materials can diffuse together, the joining will determined quality of the bond produced. Defects such as weld width inconsistency, anomalies and thermal decomposition are to be seen and observed directly from visual inspection. The inconsistency also may cause poor strength of the join.

4

1.3 Scope of Project

The aim of this project is to identify the best controllable process parameters that have big impact in laser processing. In order to produce good join, a set of process variables is developed and recommended. The values of each three chosen parameters which are laser power, travel speed and gas pressure are varied within the range of experiment while other controllable parameters are fixed. The model of laser cutting machine to perform joining process is Helius 2513 hybrid series that was made in Belgium. The laser machine is equipped with nitrogen and oxygen as laser assisted gas and carbon dioxide (CO_{2) laser beam with rated power of 3kW. The}

experimental on research work was conducted by stack joining on used high-density polyethylene (HDPE) plastics material. The joined is then examined by visual inspection and destructive test.

5

1.4 Objectives

The main objectives of this project are:

i. To investigate the ability to form stack joining of HDPE by CO_{2 laser.}

xiii

Nm - Nanometer

No/Num - Number o

- Degree

ø - Diameter

O2 - Oxygen Gas

p - Pressure

P - Power

Pa - average power

Pp - peak power

ps - Pico second

PSM - Bachelors Degree Project (Projek Sarjana Muda)

R - Radius

R - Reflectivity RF - radio-frequency

s - Seconds

SOD - Stand Off Distance STD. Standard

T - Transmissivity

t - Thickness

TEA - Transversely Excited Atmosphere Pressure

UTeM - Malaysia Melaka Technical University (Universiti Teknikal Malaysia Melaka)

UV - Ultraviolet

V - Volt

W - Watt

WJ - Water jet

- Wave length symbol

m - micrometer

Σ - Total

1 Chapter 1 is basically includes the entire report content starting from Project Background up to Plastics Joining Processes. Related information regarding laser processing is included in this chapter.

1.1 Project Background

Laser machining is widely known for cutting almost any materials. The highly focus, high-density energy source melts and evaporates portions of the workpiece in a controlled manner. Laser cutting which is one laser machining process could be referred as a material removal process accomplished by laser material interaction. Besides machining, laser also is been used in processing such as welding. Laser welding is a non-contact process and involves localized heat treating of materials to modify the surface mechanical and tribological properties (Kalpakjian, 2010).

Used products with plastics based are usually recycled. When the material is recycled, the properties of the material will not remain the same. Usually the properties are reduced and qualities of secondary products are low. Instead of re-melt or recycle the material, the used product is reused. In addition, due to high investment cost needed to setup a laser machine, optimization of existing laser cutting machine is the main goal of this study. For experimental, laser joining process will be performed by laser cutting machine instead of laser welding machine. In laser processing, the controllable process parameters are quite same for any process.

INTRODUCTION

2 The challenge in conducting this study is to identify the most suitable parameters to be applied in laser welding. This preliminary investigation will determined the capability of CO_{2 laser to produce join between materials by varying} some of process parameters. A laser cutting machine with rated power 3kW is used in this experimentation work.

The join is evaluated through visual inspection and destructive tests. Throughout this study, CO_{2 laser cutting machine has proved its ability to melt and} form join at the interface of the plastic sheets and pass minimum requirement in mechanical destructive test.

3

1.2 Problem Statement

Huge wastage of plastic bottle has become a big problem faced by the country. In average, one Malaysian citizen has produced abut 0.8kg waste per day. It is expected that in 2020, 30 000 tonne waste will be produced since only 5% of the total waste is recycled. This is a hug number for a small country like Malaysia. Due to this problem, waste plastic (HDPE) is chosen as the main material to be used in experimentation. The plastic is used in order to maintain its properties since re-meting will just reduce it. Besides, high cost is required to setup recycling equipment.

The challenge in this study is to determine which parameters that is suitable to be manipulated so that two plastic sheets can be joined together to increase its use. Since laser cutting and laser welding have almost same parameters, the requirement to buy a new laser welding machine can be eliminated because there is high possibility that a laser cutting machine can do joining without changing any part of the machine. Even though the materials can diffuse together, the joining will determined quality of the bond produced. Defects such as weld width inconsistency, anomalies and thermal decomposition are to be seen and observed directly from visual inspection. The inconsistency also may cause poor strength of the join.

4

1.3 Scope of Project

The aim of this project is to identify the best controllable process parameters that have big impact in laser processing. In order to produce good join, a set of process variables is developed and recommended. The values of each three chosen parameters which are laser power, travel speed and gas pressure are varied within the range of experiment while other controllable parameters are fixed. The model of laser cutting machine to perform joining process is Helius 2513 hybrid series that was made in Belgium. The laser machine is equipped with nitrogen and oxygen as laser assisted gas and carbon dioxide (CO_{2) laser beam with rated power of 3kW. The} experimental on research work was conducted by stack joining on used high-density polyethylene (HDPE) plastics material. The joined is then examined by visual inspection and destructive test.

5

1.4 Objectives

The main objectives of this project are:

i. To investigate the ability to form stack joining of HDPE by CO_{2 laser.} ii. To conduct quality and performance analysis of the join.