Plasma Arc Welding (PAW)

Total Page：16

File Type：pdf, Size：1020Kb

Gas Shielded Welding Processes - . Plasma Arc Welding (PAW) Lecture 5 p1 PAW: Process Fundamentals ( • In PAW the heat source is an arc maintained between a non-consumable electrode and the workpiece • The arc is constricted by a cooled orifice that surrounds the electrode • Inert gas is supplied separately to the orifice and to a surrounding low-velocity shielding flow 5 p2 PAW: Comparison with GTAW SHIELDING ELECTRODE GAS SHIELDING t GAS . GTAW PAW Lecture 5 p3 PAW: Effect of Arc Constriction ( GTAW PAW Arc Temperatur~s • >24000K • 18 000 - 24 000 " • 14000 - 18 000 " • 10 000 - 14000 " 200 A, 15 V 5 p4 PAW Modes CONSTRICTING NOZZLE ORIFICE GAS SHIELDING GAS TRANSFERRED ARC NON-TRANSFERRED ARC Lecture 5 p5. PAW: Keyhole technique ( KEYHOLE WELD BEAD p6 PAW: Welding Procedures Keyhole welding of stainless steel sheet T = Matenal Thickness -4 E 20 B= Upper Clamp Spacing E . C =Back-up Bar Spacing ......... 3 15 A = Weld Current () B - 2 III B 10 -j C 1 7-- ~I 1 ~~ L:--_--L.__---'-__----:-I.::-...J 'ViC .5 1.0 1.5 T(mm) Lecture 5 p7 PAW: Backing for Keyhole Welding ( TORCH- ~ \!~Il. PlASMA JIT . BACKINGGA BACKING BAR p8 PAW Welding Equipment START/STOP SWITCH .-----.-1 COOLANT o 01--------, ,.-----1CIRCULATOR '--'-~IFICEGAS -rL--.!-Jl IELD GAS -----I TORCH WER & COOLANT IN CONTROLLER 1-- --, WER & COOLANT OUT -.....----r----' WORK WELDING GAS POWER SOURCE REMOTE CURRENT CONTROL Lecture 5 p£ PAW Welding Torch ( COOLANT OUTLET ORIFICE GAS INLET -----.,POWER CONDUCTORS COOLANT INLET HIELDING GAS INLET 14+--f+----'TUNGSTEN ELECTRODE ORIFICE BODY .,OUTER SHIELD CUP ~5 p10 PAW Applications • Very thin sheet (down to 0.1 mm), wire and mesh sections in microplasma mode • Full penetration welding of sheet and prate up to about 5mm thick in single pass keyhole mode. • Keyhole mode usually in flat position, rarely for tube and pipe welding • Melt-in mode applications similar to GTAW Lecture 5 P 11. PAW Capabilities & Limitations ( + Higher intensity heat - Little tolerance for joint source than GTAW misalignment _ - higher welding speeds - Torch orifice must be . - reduced heat input and well maintained for distortion consistent weld quality + Insensitive to torch - PAW torches are more stand-off distance bulkier and more + Applicable to almost all difficult to manipulate metals manually than GTAW + Adaptable to precision mechanized applications ·5 p12 Electron Beam _. & Laser Welding Lecture 5 p13 EBW, LBW Fundamentals ( , • Heat source is radiant energy from focused beam of electrons or photons (light) • Shielding from atmospheric contamination by welding in vacuum chamber (EBW), inert gas shield (LBW) e5 p14 LBW, EBW Capabilities and Limitations + Very high energy density - Little tolerance for joint heat sources misalignment _ + Very deep penetration in - EBW requirement for "keyhole" mode vacuum chamber + Narrow welds and HAl limits maximum size + High welding speed that can be welded + Reduced heat input and - Equipment is complex distortion and costly. + Adaptable to precision mechanized applications Lecture 5 P 15.

Copy Link

Recommended publications

Welding and Joining Guidelines
Welding and Joining Guidelines The HASTELLOY® and HAYNES® alloys are known for their good weldability, which is defined as the ability of a material to be welded and to perform satisfactorily in the imposed service environment. The service performance of the welded component should be given the utmost importance when determining a suitable weld process or procedure. If proper welding techniques and procedures are followed, high-quality welds can be produced with conventional arc welding processes. However, please be aware of the proper techniques for welding these types of alloys and the differences compared to the more common carbon and stainless steels. The following information should provide a basis for properly welding the HASTELLOY® and HAYNES® alloys. For further information, please consult the references listed throughout each section. It is also important to review any alloy- specific welding considerations prior to determining a suitable welding procedure. The most common welding processes used to weld the HASTELLOY® and HAYNES® alloys are the gas tungsten arc welding (GTAW / “TIG”), gas metal arc welding (GMAW / “MIG”), and shielded metal arc welding (SMAW / “Stick”) processes. In addition to these common arc welding processes, other welding processes such plasma arc welding (PAW), resistance spot welding (RSW), laser beam welding (LBW), and electron beam welding (EBW) are used. Submerged arc welding (SAW) is generally discouraged as this process is characterized by high heat input to the base metal, which promotes distortion, hot cracking, and precipitation of secondary phases that can be detrimental to material properties and performance. The introduction of flux elements to the weld also makes it difficult to achieve a proper chemical composition in the weld deposit.
[Show full text]
Tendencies in Development of Plasma-Arc Welding of Aluminium Alloys*
MAIN TENDENCIES IN DEVELOPMENT OF PLASMA-ARC WELDING OF ALUMINIUM ALLOYS* A.A. GRINYUK2, 3, V.N. KORZHIK1, 2, V.E. SHEVCHENKO1, 2, A.A. BABICH2, S.I. PELESHENKO4, V.G. CHAJKA2, A.F. TISHCHENKO2 and G.V. KOVBASENKO2 1Chinese-Ukrainian E.O. Paton Welding Institute (Guangdong General Research Institute of Industrial Technology) (Guangzhou Research Institute of Non-Ferrous Metals, PRC) 2E.O. Paton Electric Welding Institute, NASU 11 Bozhenko Str., 03680, Kiev, Ukraine. E-mail: [email protected] 3NTUU «Kiev Polytechnic Institute» 6/2 Dashavskaya Str., 03056, Kiev, Ukraine. E-mail: [email protected] 4South China University of Technology 510641, Guangzhou, PRC. E-mail: [email protected] Publications, describing the characteristic technologies of aluminium alloy welding by an arc constricted by high-velocity inert gas flow were analyzed. It is shown that plasma-arc welding (PAW) is further development of the process of nonconsumable-electrode inert-gas welding. It is established that during development of PAW of aluminium alloys, there was a transition from alternating sinusoidal current to reverse polarity direct current, and furtheron to variable polarity asymmetrical current with rectangular current waveform. A more promising direction of improvement of PAW equipment is transition from specialized power sources to modular design of PAW system, based on power sources applied for noncon- sumable electrode welding and plasma modules. Further path of improvement of the processes of aluminium alloy PAW is combined or hybrid application of several heat sources, including the constricted arc and consumable-electrode arc. In the authors’ opinion, hybrid consumable-electrode PAW with hollow anode and axial wire feed in the most promising variant.
[Show full text]
Study on Weld Quality Characteristics of Micro Plasma Arc Welded Austenitic Stainless Steels
Available online at www.sciencedirect.com ScienceDirect Procedia Engineering 97 ( 2014 ) 752 – 757 12th GLOBAL CONGRESS ON MANUFACTURING AND MANAGEMENT, GCMM 2014 Study on Weld Quality Characteristics of Micro Plasma Arc Welded Austenitic Stainless Steels Kondapalli Siva Prasada*, Chalamalasetti Srinivasa Raob, Damera Nageswara Raoc a*Anil Neerukonda Institute of Technology & Sciences, Visakhapatnam, INDIA bU College of Engineering, Andhra University, Visakhapatnam, INDIA cCenturion University of Technology & Management, Odisha, INDIA Abstract Micro Plasma Arc Welding (MPAW) is one of the important arc welding process commonly using in sheet metal industry for manufacturing metal bellows, metal diaphragms etc. The paper focuses on weld quality characteristics like weld bead geometry, grain size, hardness and ultimate tensile strength of MPAW welded joints of various austenitic stainless steels namely AISI 316L, AISI 316Ti, and AISI 321. From the analysis carried out it is noticed that for the same thickness of work piece material and same welding conditions, AISI 304L has achieved sound weld bead geometry, highest tensile strength and hardness. However it is noticed that AISI 316L has attained lowest tensile strength, AISI 321 has lowest hardness and grain size. © 2014201 4The The Authors. Authors. Published Published by Elsevier by Elsevier Ltd. This Ltd is .an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Selection and peer-review under responsibility of the Organizing Committee of GCMM 2014. Selection and peer-review under responsibility of the Organizing Committee of GCMM 2014 Keywords: Micro Plasma Arc Welding,;Austenitic Stainless steel; Weld bead geometry; grain size; hardness; tensile strength 1.
[Show full text]
Arc Welding • Electric Arc Is Produced When Current Flows Across the Air Gap Between the End of Metal Electrode and Work Surface
Arc welding • Electric arc is produced when current flows across the air gap between the end of metal electrode and work surface. • Electric discharge occurring in the air gap. • The temperature at centre of arc is 6500C. • Only 3600C is utilized for melting of metal. • Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals when cool result in a binding of the metals. • Equipments: • Transformer: To change high voltage and low amperage to a low voltage 20-80 V and high 80- 500 amps. • In arc welding, the voltage is directly related to the length of the arc, and the current is related to the amount of heat input. • Generator: Driven by motor. Generates D.C. • Rectifier: The output of step down transformer is to rectifier to converts A.C. to D.C. • Electrode: Metal stick to create arc. A.C.plant: • Simple, less cost, No moving parts, low maintenance cost, no change of polarity. • Gives smoother arc when using high current. • Not suitable for non-ferrous and thin sheets. • Electric shock is more intense. • D.C.Plant • Can be used for ferrous ,non-ferrous & thin sheets • Stable arc, fine settings are possible • Easy of operation, suitable for over head welding. • Safer to use. • More expensive, high maintenance cost, arc blow(arc is forced away from weld point). • Polarity: It indicates the direction of current flow in D.C. In D.C. 2/3 of heat is liberated from + end and 1/3 of heat is liberated from - end.
[Show full text]
MSL Engineering Limited Platinum Blue House 1St Floor, 18 the Avenue Egham, Surrey, TW20 9AB
SMR Final Report 121404 Purpose of Issue Rev Date of Issue Author Agreed Approved Issued for information 0 Aug 2004 SM Issued for internal comment 1 November 2004 AFD DJM JB Issued as Final Report 2 December 2004 AFD DJM JB This Final report has been reviewed and approved by the Mineral Management Service. Approval does not signify that the contents necessarily reflect the views and policies of the Service, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This study was funded by the Mineral Management Service, U.S. Department of the Interior, Washington, D.C., under Contract Number 1435-01-04-CT-35320 ASSESSMENT OF REPAIR TECHNIQUES FOR AGEING OR DAMAGED STRUCTURES Project #502 DOC REF C357R001 Rev 1 NOV 2004 MSL Engineering Limited Platinum Blue House 1st Floor, 18 The Avenue Egham, Surrey, TW20 9AB Tel: +44 (0)1784 439194 Fax: +44 (0)1784 439198 E-mail: [email protected] C357R001Rev 2, December 2004 MMS Project #502 NUMBER DETAILS OF REVISION 0 Issued for information, August 2004 1 Issued for comment, November 2004. Extensive revisions throughout, including restructuring of report. 2 Issued as Final Report, December 2004. Conversion table added, Figure showing clamp details to avoid added, and general editorial revisions. C357R001Rev 2, December 2004 MMS Project #502 Assessment of Repair Techniques for Ageing or Damaged Structures By Dr. Adrian F Dier MSL Services Corporation Final Project Report: ASSESSMENT OF REPAIR TECHNIQUES FOR AGEING OR DAMAGED STRUCTURES MMS Project Number 502 November 2004 C357R001Rev 2, December 2004 i This Final report has been reviewed a nd approved by the Mineral Management Service.
[Show full text]
Plasma Arc Welding: Process, Sensing, Control and Modeling
Journal of Manufacturing Processes 16 (2014) 74–85 Contents lists available at ScienceDirect Journal of Manufacturing Processes j ournal homepage: www.elsevier.com/locate/manpro Technical paper Plasma arc welding: Process, sensing, control and modeling ∗ C.S. Wu , L. Wang, W.J. Ren, X.Y. Zhang MOE Key Lab for Liquid-Solid Structure Evolution and Materials Processing, and Institute of Materials Joining, Shandong University, Jinan 250061, China a r t i c l e i n f o a b s t r a c t Article history: This article introduces the basic principles of plasma arc welding (PAW) and provides a survey of the Received 18 March 2013 latest research and applications in the field. The PAW process is compared to gas tungsten arc welding, Received in revised form 10 May 2013 its process characteristics are listed, the classification is made, and two modes of operation in PAW, i.e., Accepted 5 June 2013 melt-in and keyhole, are explained. The keyhole mechanism and its influencing factors are introduced. Available online 12 July 2013 The sensing and control methodologies of the PAW process are reviewed. The coupled behaviors of weld pool and keyhole, the heat transfer and fluid flow as well as three-dimensional modeling and simulation Keywords: in PAW are discussed. Finally, a novel PAW process variant, the controlled pulse keyholing process and Plasma arc welding Keyhole the corresponding experimental system are introduced. Sensing © 2013 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved. Control Modeling 1. Introduction between the electrode and the workpiece. This is termed as a trans- ferred arc.
[Show full text]
Download Article
Advances in Intelligent Systems Research, volume 130 6th International Conference on Mechatronics, Computer and Education Informationization (MCEI 2016) Surface Treatment Technology for Increasing Wear Resistance of Aluminum Alloy Fan Lidan1, a *, Chen Youquan2,b, Yang Feng1,c ,Yang Zhuojuan1,d 1College of Mechanical Engineering Jilin Teachers’ Institute of Engineering＆Technology Changchun, China 2Department of Mechanical Engineering Changchun Institute of Engineering Technology Changchun, China [email protected], [email protected], [email protected]* Keywords: Engine; Aluminum alloy parts; Plasma; Laser Abstract. Research and application of various surface treatment technologies in increasing the wear performance of aluminum alloy engine parts are introduced. These technologies include plasma spraying, plasma arc welding, plasma scanning, plasma electrolyzing, electroplating,physical vapour deposition and laser cladding technologies. Vistas of application of surfacestrengthening aluminum alloy wear resistant parts are prospected. Introduction The lightweight of automobile and motorcycle is a very important development trend. Potential the whole or part of the body material is made of high density steel. Iron material replaced by a small density of aluminum alloy material, you can greatly reduce the car Body mass. Engine mass in the body mass in a large proportion of the engine is replaced by the original cast iron material for aluminum alloy. Poor wear resistance, if not processed, will make the engine cylinder wall. In contact with the piston part of the production of serious wear and tear, greatly reduce the engine service life of. At present, the general solution is in the aluminum alloy engine with a cast iron cylinder liner, Piston rings and cast iron cylinder liners instead of aluminum alloy gold material for friction, so as to avoid the wear of aluminum alloy.
[Show full text]
Chapter 6 Arc Welding
Revised Edition: 2016 ISBN 978-1-283-49257-7 © All rights reserved. Published by: Research World 48 West 48 Street, Suite 1116, New York, NY 10036, United States Email: [email protected] Table of Contents Chapter 1 - Welding Chapter 2 - Fabrication (Metal) Chapter 3 - Electron Beam Welding and Friction Welding Chapter 4 - Oxy-Fuel Welding and Cutting Chapter 5 - Electric Resistance Welding Chapter 6 - Arc Welding Chapter 7 - Plastic Welding Chapter 8 - Nondestructive Testing Chapter 9 - Ultrasonic Welding Chapter 10 - Welding Defect Chapter 11 - Hyperbaric Welding and Orbital Welding Chapter 12 - Friction Stud Welding Chapter 13 WT- Welding Joints ________________________WORLD TECHNOLOGIES________________________ Chapter 1 Welding WT Gas metal arc welding ________________________WORLD TECHNOLOGIES________________________ Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material (the weld pool) that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself, to produce the weld. This is in contrast with soldering and brazing, which involve melting a lower-melting-point material between the workpieces to form a bond between them, without melting the workpieces. Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound. While often an industrial process, welding can be done in many different environments, including open air, under water and in outer space. Regardless of location, welding remains dangerous, and precautions are taken to avoid burns, electric shock, eye damage, poisonous fumes, and overexposure to ultraviolet light.
[Show full text]
Effects of Welding on Health IV Effects of Welding on Health IV
Effects of Welding on Health IV Effects of Welding on Health IV An up-dated (December 1980-June 1982) literature survey and evaluation of the data recorded since the publication of the first report, to understand and improve the occupational health of welding personnel. By Winifred G. Palmer Submitted by: Tracor Jitco 1776 E. Jefferson Street Rockville, MD 20852 Submitted to: SAFETY AND HEALTH COMMITTEE AMERICAN WELDING SOCIETY 550 N.W. LeJeune Road Miami, FL 33126 International Standard Book Number: 0-87171-230-X American Welding Society, 550 LeJeune Road, Miami, FL 33126 ©1983 by American Welding Society. All rights reserved. This report is published as a service and convenience to the welding industry and is the product of an independent contractor (Tracor Jitco) which is solely responsible for its contents. The materials in this report have not been independently reviewed or verified and are only offered as information. AWS assumes no responsibility for any claims that may arise from the use of this information. Users must make independent investigations to determine the applicability of this information for their purposes. Printed in the United States of America Contents Personnel v Acknowledgements vii Preface ix Introduction xi Executive Summary xiii Technical Summary xv /. The Exposure 1 1.1 Fumes 1 1.2 Gases 5 1.3 Protective Coatings 7 1.4 Electromagnetic Radiation 9 1.5 Noise 10 2. Effects of Welding on Human Health 11 2.1 Respiratory Tract 11 2.2 Cancer 15 2.3 Effects on the Ear and Hearing 19 2.4 Effects on the Eye and Vision 19 2.5 Effects on the Skin 20 2.6 Effects on the Cardiovascular System 21 2.7 Effects on the Nervous System 21 2.8 Effects on the Liver 22 2.9 Effects on the Musculoskeletal System 22 2.10 Effects on the Urogenital Tract 23 2.11 Effects on the Teeth and Oral Cavity 23 2.12 Metal Fume Fever 23 2.13 Sensitivity to Fume Components 23 2.14 Biochemical Changes 24 2.15 Human Fatality 25 2.16 Occupational Medicine 25 3.
[Show full text]
Welding, Brazing, and Thermal Cutting
\j L i □ K n Criteria for a Recommended Standard Welding, Brazing, and Thermal Cutting U.S. DEPARTM f NT OF H E A LT H AND HUMAN SER V IC ES PUBLIC HEALTH SER V IC E CENTERS FOR DISEASE CONTROL NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH' CRITERIA FOR A RECOMMENDED STANDARD (elding, Brazing, and Thermal Cutting U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES PUBLIC HEALTH SERVICE CENTERS FOR DISEASE CONTROL NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH DIVISION OF STANDARDS DEVELOPMENT AND TECHNOLOGY TRANSFER ApriI 1988 DISCLAIMER Mention of the name of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health. DHHS (NIOSH) Publication No. 88-110 to r sat* by II» Superintendent of Documenti, U.S. Government Print Inc Office, »••hinglon. D.C. 20403 FOREWORD The purpose of the Occupational Safety and Health Act of 1970 (Public Law 91-596) is to ensure safe and healthful working conditions for every working person and to preserve our human resources by providing medical and other criteria that will ensure, insofar as practicable, that no worker will suffer diminished health, functional capacity, or life expectancy as a result of his or her work experience. The Act authorizes the National Institute for Occupational Safety and Health (NIOSH) to develop and recommend occupational safety and health standards and to develop criteria for improving them. By this means, NIOSH communicates these criteria both to regulatory agencies and others in the community of occupational safety and health. Criteria documents provide the basis for the occupational health and safety standards sought by Congress.
[Show full text]
Handbook on Welding Techniques
dsoy dk;Zky;hu mi;ksx gsrq (For Official Use Only) Hkkjr ljdkj GOVERNMENT OF INDIA jsy ea=ky; MINISTRY OF RAILWAYS HANDBOOK ON WELDING TECHNIQUES END USER: Newly Recruited/ Promoted Welders CAMTECH/ E/ 14-15/ Welding/ 1.0 February, 2015 egkjktiqj Xokfy;j & 474 005 , Maharajpur, GWALIOR - 474 005 HANDBOOK ON WELDING TECHNIQUES QUALITY POLICY “To develop safe, modern and cost effective Railway Technology complying with Statutory and Regulatory requirements, through excellence in Research, Designs and Standards and Continual improvements in Quality Management System to cater to growing demand of passenger and freight traffic on the railways”. FOREWORD Welding is a very common metal joining technology and it is widely used in Railways in various production and maintenance units. Railways recruit ITI qualified welders as well as promote staff to welder category by providing appropriate training. CAMTECH has prepared this handbook on “Welding Techniques” to provide basic information on the subject. This handbook contains various terms used in electric arc and gas welding. I hope this handbook will prove to be useful for the newly recruited and promoted welders as well as working welders for updating their knowledge. CAMTECH, Gwalior A. R. Tupe Date : 23rd Feb, 2015 Executive Director PREFACE Welding is the most commonly used method of joining and repairing metallic structures permanently. The basic knowledge of weld procedures, weld joints, different techniques is essential to upgrade the workmanship of a welder and to improve productivity in an industry. CAMTECH has prepared this handbook on “Welding Techniques” by compiling useful information from various sources and books available on the subject.
[Show full text]
Plasma Arc Welding
Plasma Arc Welding Plasma Arc Welding Process The plasma arc welding (PAW) process is sometimes compared to gas tungsten arc welding (GTAW), and there are some similarities, such as the use of a nonconsumable tungsten electrode, low heat input and weld quality, but the PAW process has unique characteristics that make it distinct from GTAW. The electrode with the PAW process is recessed in a constricting nozzle. Pressurised gas is forced through a small orifice at the base of the nozzle. This orifice gas, in conjunction with the current flow from the electrode, creates a highly charged ionized plasma for current conducting. Around this constricting nozzle is an outer gas nozzle that directs a shielding gas (Fig.1). This setup provides PAW with some of the distinct characteristics that separate it from GTAW: the arc is narrow and directional; the weld is penetrating; width of the heat-affected zone is narrow; sensitivity to standoff distance is reduced; and the possibility of the electrode touching the workpiece and subsequent contamination is eliminated. Plasma arc welding lends itself to two different arc modes: transferred and nontransferred (Fig.2). With the transferred arc, the workpiece is part of the circuit, but that is not so with the nontransferred arc. In the transferred mode, the arc is established between the electrode and the workpiece, but in the nontransferred mode, the arc is established between the electrode and the constricting orifice with the force of the plasma gas directing heat to the workpiece. This arc is good for cutting or for joining a nonconductive workpiece.
[Show full text]