Investigation Of Plate Welding Quality By Robot Welding Using Nondestructive Technique

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

INVESTIGATION OF PLATE WELDING QUALITY BY ROBOT

WELDING USING NONDESTRUCTIVE TECHNIQUE

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

(Manufacturing Process) with Honours.

by

HARYATIE BINTI SAMSURI

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ABSTRACT

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ABSTRAK

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DEDICATION

I dedicate this work to my special family, my special friend in gratitude and all my loving friends because of her/ his patience and understanding support in all my

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ACKNOWLEDGEMENT

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TABLE OF CONTENT

Abstract i

Abstrak ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Table ix

List of Figures xi

List of Abbreviations xiii

1. INTRODUCTION

1.1 Welding 1

1.1.1 Development of Modern Welding Processes 1

1.2 Problem Statement 2

1.3 Objective 2

1.4 Scope of Research 3

2. LITERATURE REVIEW

2.1 Fusion Welding Processes 4 2.1.1 History and Development 4 2.1.2 Oxyfuel Gas Welding 4 2.1.3 Arc Welding Processes of Non- Consumable Electrode 5 2.1.4 Arc Welding Processes of Consumable Electrode 7 2.1.5 Gas Metal Arc Welding 7 2.1.6 Electrodes for Arc Welding 8 2.1.7 Welding Parameter 8

2.1.8 The Weld Joint 9

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2.2 Robot Welding 12

2.2.1 Definition 12

2.2.2 Synchromotion 12

2.2.3 Utilizing Features and Function 14 2.2.4 Simultaneous Control 15 2.2.5 Advantage and disadvantage of robot welding 17 2.3 Nondestructive Techniques (NDT) 18

2.3.1 Definition 18

2.3.2 Types of NDT Technique 19 2.3.3 Ultrasonic testing 20 2.3.4 Advantages and Disadvantage of Ultrasonic Testing 21 2.3.5 Reflection Characteristic of Sound Waves When

Striking Discontinuities 22

2.3.6 Improvement 23

3. METHODOLOGY

3.1 Sample Preparation and Gathering 24

3.2 Raw Material 24

3.2.1 Mild Steel 25

3.2.2 Stainless steel 26 3.2.3 Differentiation between mild steel and stainless steel 27

3.3 Filler Wire 29

3.4 Joint Type 29

3.5 Research Procedure 30

3.6 Welding Method 31

3.7 Parameter Selection 31 3.7.1 Constant Parameter 31 3.7.2 Variable parameter 32

3.8 Robot Welding 33

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3.8.2 Standard Operation of Robot Welding (SOP) 34 3.8.3 Standard Operation ON and OFF System 36

3.8.4 Coding 36

3.9 Testing Method 37

3.9.1 Equipment 38

3.10 Testing Technique 41 3.10.1 Calibration of the Test Sample 42 3.10.2 Standardized of Test Sample 42 3.10.3 Performance of Test Sample 42 3.10.4 Interpretation of Result 42 3.11 Contact Testing 43

3.11.1 General 43

3.12.2 Why ultrasonic testing 44 3.11.3 Comparison between ultrasonic testing and radiographic testing 45 3.11.4 Basic Method 46 3.11.5 Testing system 47 3.11.6 Parameter consideration 49

3.11.7 Couplant 52

3.11.8 Evaluating the defect 53 3.11.9 Technique define crack from floating card 54

3.11.10 Procedure 55

4. RESULT

4.1 Welding Result 56

4.1.1 Mild Steel 56

4.1.2 Stainless Steel 58 4.2 Ultrasonic Testing Result 60

4.2.1 Mild Steel 60

viii 5. DISCUSSION

5.1 Mild Steel 67

5.2 Stainless Steel 72 5.3 Propose the appropriate method of controlling the

parameters for better welding quality 75

6. CONCLUSION

6.1Conclusion 78

REFERENCES 80

APPENDICES A

Gannt Chart for Project Activities for PSM 1 83 Gannt Chart for Project Activities for PSM 2 84

APPENDICES B

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LIST OF TABLE

3. METHODOLOGY

3.1 Chemical composition of mild steel filler wire 26 [Sources: Barry M. Patchett, 1998]

3.2 Chemical composition of stainless steel of filler wire 27 [Sources: Barry M. Patchett, 1998]

3.3 Description of robot welding 33 [Sources: Manual Lab Machine Shop]

4. RESULT

Welding Result (Mild Steel) 56 4.1 Variable welding current according the reference value 56 4.2 Variable welding voltage according the reference value 57 4.3 Variable welding speed according the reference value 57 Welding Result (Stainless Steel) 58 4.4 Variable welding current according the reference value 58 4.5 Variable welding voltage according the reference value 58 4.6 Variable welding speed according the reference value 59 Ultrasonic Testing Result (Mild Steel) 60 4.7 Variable welding current 60 4.8 Variable welding voltage 61 4.9 Variable welding speed 62 Ultrasonic Testing Result (Stainless Steel) 63 4.10 Variable welding current 63 4.11 Variable welding voltage 64 4.12 Variable welding speed 65

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Mild Steel 67

5.1 Welding current and its defect 67 5.2 Welding current and its defect 67 5.3 Welding voltage and its defect 69 5.4 Welding voltage and its defect 69 5.5 Welding speed and its defect 70 5.6 Welding speed and its defect 70

Stainless Steel 72

5.7 Welding current and its defect 72 5.8 Welding current and its defect 72 5.9 Welding voltage and its defect 73 5.10 Welding voltage and its defect 73 5.11 Welding speed and its defect 74 5.12 Welding speed and its defect 74

6. CONCLUSION

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LIST OF FIGURES

1. INTRODUCTION

2. LITERATURE REVIEW

2.1 Basic types of oxyacetylene flames 5 (Sources:Kalpakjian Schmid, 2001)

2.2 (a) Gas tungsten arc welding process formerly tungsten 6 inert gas welding (TIG welding). (b) Equipment TIG operations (Sources:Kalpakjian Schmid, 2001)

2.3 The shielded metal arc welding process 7 (Sources:Kalpakjian Schmid, 2001)

2.4 The characteristics of a typical fusion weld zone 9 (Sources:Kalpakjian Schmid, 2001)

2.5 Various discontinuities in fusion welds 11 (Sources:Kalpakjian Schmid, 2001)

2.6 Robot welding 13

3. METHODOLOGY

3.1 Groove shape on the plate 25 3.2 Stainless steel plate 306L 25 3.3 Mild steel plate 26

3.4 Welding angle 32

3.5 Typical ultrasonic contact test displaying 39 (Source: Jimmy Gan, 2006)

3.6 Sweep delay adjustment 40 (Source: Jimmy Gan, 2006)

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3.8 Typical contact test discontinuity indication 44 (Source: Jimmy Gan, 2006)

3.9 Schematic of pulse echo flaw detector 48 (Source: Galvery W, 2007)

3.10 Full set of ultrasonic tester machine 50

3.11 CTR screen 50

3.12 Calibration block 51 3.13 Highest echo signal 52 3.14 Lowest echo signal 52 3.15 First highest of echo signal 53 3.16 Second highest of echo signal 53

3.17 Weld size 54

5. DISCUSSION

5.1 Crack or flaw in and around a weld 66 (Source: Galvery W, 2007)

5.2 Slag inclusions 68 (Source: Galvery W, 2007)

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LIST OF ABBREVIATION

A or AMP - Ampere

AC - Alternating Current AE or AET - Alternate Ending AS - Alternate Start BP - Beam Path C - Circular DC - Direct Current

ECT - Eddy Current Testing EXT INPUT - External Input

GMAW - Gas Metal Arc Welding HAZ - Heat Affected Zone HC - Harmonious circle HL - Harmonious Line

HLO - Harmonious Line Orientation

HLX - Interpolation in Simultaneous Control HO - Harmonious Circle Orientation HP - Harmonious Position

IP - Initial Pulses

LX - Uniform Interpolation MIG Welding - Gas Shielded Arc Welding NDT - Nondestructive Testing OAW - Oxyacetylene Gas Welding OFW - Oxyfuel Gas Welding P - Positioning

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Sa - Sound Path SD - Surface Distance

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CHAPTER 1

INTRODUCTION

This chapter provides a general background of the project. It briefly describes the general discussion of joining processes and focus on the subject being discussed easily. It also explains the problem statements, objectives of the study, and scope of the research.

1.1 Welding

Welding is one type joining process involve the partial melting and fusion of the joint between two workpiece. Fusion welding is defined as melting together and coalescing materials by means of heat [Kalpakjian et. al, 2006].

Joining process is carried out in the various ways. The mechanical joining method is derived from metalworking processes. The solid techniques are based on the adhesion and deformation [Gourd, 1998].

1.1.1 Development of Modern Welding Processes

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1.2 Problem statement

Today we can see the welding are generally used in manual or using the automated robot. So, both of two categories of welding methods are totally different. For the manual welding, these processes use a power supply created by welder to create and maintain an electric arc between an electrode and the base material to melt metals at the welding point. They was used either direct (DC) or alternating current (AC), and consumable or nonconsumable electrodes. The welding region is sometimes protected by some type of inert or semi inert gas, known as a shielding gas and filler material is sometimes used as well. Meanwhile for robots welding, are the parameters was already setting by operator with its controller.

Then, the welding process done by robots as the robots is the welder. But for manual welding, the welder is human. So the final product after welding process are difference each other because both of them have their own criteria. So from this case, we can know mostly about the different of performance result done by robots welding and manual welding. And at the same time the welding quality, defects, skill of the welder and position done by welder also can relate with this case. This is because the parameters effecting in welding quality is the main factor of discontinuities caused by inadequate or careless application of proper welding technologies or by poor welder training. From this major discontinuities that affect weld quality are solved with a best method for controlling those parameters factors.

1.3 Objective

The main purpose of this project was listed below.

i. To investigate the performance of plate welding quality and its welding defects. ii. To identify the parameters effecting the welding quality.

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1.4 Scope of research

The scope of study was listed below.

i. To learn how to use the robot welding practically. ii. To identify the parameters affected on welds.

iii. To perform the joining works on the sample of work piece. iv. To carry out the testing of nondestructive techniques.

v. To analyze the result obtained from the equipment.

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CHAPTER 2

LITERATURE REVIEW

This chapter describes the information from many sources that it explains to readers what has motivated the study by giving definition, identifying the causes and effects, listing method used, provides historical background, describing the problem faced and stating the advantages or disadvantages.

2.1 Fusion Welding Processes

2.1.1 History and development

The welding and oxyfuel welding was developed in 1893. Acetylene was discovered in 1836 by Edmund Davy. The automatic welding was introduced in 1920 which is an electrode wire was fed continuously [Cary et. al, 2005]. Shielded metal arc welding was developed around 1950 by using a flux coated consumable electrode. The plasma arc welding was developed in the same year. The electro slag welding was introduced in 1958 and it was followed by an electro gas welding in years of 1961 [Cary et. al, 2005].

2.1.2 Oxyfuel gas welding

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acetylene; this process is known as Oxyacetylene Gas Welding (OAW). Figure 2.1 is showed the three basic types of oxyacetylene flames used in oxyfuel gas welding and cutting operation [Kalpakjian et. al, 2006].

Figure 2.1: Basic types of oxyacetylene flames (Source: Kalpakjian Schmid, 2001)

i. Flame type

The important factor in oxyfuel gas welding is the proportion of acetylene and oxygen.

ii. Filler metal

Filler metal is used to supply additional metal to the weld zone during welding. It suited as filler rod or wire and coated with flux as to check oxidation of the surfaces of the parts being welded by generating a gaseous shield around the weld zone.

iii. Pressure gas welding

The welding of two components started with the heating of the interface by means of a torch using an oxyacetylene gas mixture. The torch was withdrawn after the interface begins to melt.

2.1.3 Arc welding processes of non- consumable electrode

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of the weld zone. The types of welding techniques stated and listed below [Kalpakjian et. al, 2006].

Figure 2.2: (a) Gas tungsten arc welding process formerly tungsten inert gas welding (Source: Kalpakjian

Schmid, 2001). (b) Equipment TIG operations (Source: Kalpakjian Schmid, 2001).

i. Gas tungsten arc welding

The filler metal is supplied from a filler wire in gas tungsten arc welding (TIG) like Figure 2.2 above. It‟s more suitable for thin metal. The tungsten electrode is not consumed in this operation, so that the arc gap is maintained at a constant current level. Flux is not used but the filler wire are similar to the metal to welded.

ii. Plasma arc welding

A concentrated plasma arc is produced and directed towards the weld area in plasma arc welding. Deep and narrow weld can be made by this process at high welding speed.

iii. Atomic hydrogen welding