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The tenth conference was held June 6 and 7, 2000, in Copenhagen, Denmark, under the leadership of The Welding Institute and the Force Institute. The papers were divided into sessions on sensor and vision systems, equipment control, manufacturing and production, education and training, and modeling and simulation. The proceedings are available in both paper and electronic forms from Woodhead Publishing Ltd.

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Except where attributed to NIST authors, the content of individual sections of this volume has neither been reviewed nor edited by the National Institute of Standards and Technology. NIST therefore accepts no responsibility for comments or recommendations therein. The mention of trade names in this volume neither constitutes nor implies any endorsement or recommendation by the National Institute of Standards and Technology.

Acknowledgment: The editors wish to express their appreciation to those who helped run the conference, chair the sessions, and prepare these proceedings, especially to Gladys Santana of the American Welding Society and Vonnie Ciaranello of NIST.

Session A1: Sensing and Control I: GMAW

THE EXPERIMENTAL STUDIES ON THE PROCESS-INTEGRATED QUALITY ASSURANCE IN PULSED CURRENT GMA WELDING OF ALUMINUM

Dr. S. Rajasekaran

ABSTRACT

Al-Mg alloys are widely used in the production of new breed lightweight cars. The pulsed current gas metal arc welding (GMAW-P) is widely used to weld these alloys. However, quality of the weld mainly depends upon the parameters of the pulsed current such as peak current (Ip), peak duration (Tp), background current (IB), background duration (TB), welding speed (Ws), and wire feed speed (WF). Selecting the most suitable GMAW-P parameter is very complex due to interdependence of parameters.

Therefore effects of the GMAW-P parameters on different types of droplet detachments, namely one droplet detachment during peak duration, one droplet detachment during background duration, two droplets detachment during peak duration, and three droplets detachment during peak duration have been studied. The best type of droplet detachment for GMAW-P has been selected on the basis of process-integrated quality assurance. This process-integrated quality assurance enables online monitoring of welding voltage, welding current as well as the reproduction of welding data and complete documentation of all parameters and welding machine adjustments. Therefore, this method was used to select the suitable pulse parameter to welding.

The 1.2mm diameter of ER 5356 filler metal and 6mm thick AA 5083 Al-Mg alloy base metal were used throughout welding experiments. Electrical signal especially pulsed current waveform as time function, contains essential information about physical phenomena in arc. Therefore, the average current per pulse cycle time was measured from the pulsed current waveforms using AutoCAD 2000 and a self-developed computer software EL-JS. The statistical analysis was carried out to determine uniformity of average current. Results show that one droplet detachment during peak duration can provide stable weld compared to other types of droplet detachments. This experimental study helped to achieve high-quality cost-effective welds with high production rate.

KEY WORDS

Pulsed Current GMAW, Pulse Parameters, Waveform, Process-Integrated Quality Assurance, Al-Mg Alloys Welding, Droplet Detachment, Data Analysis, Computer Data, Arc Sensing.

At the time of this work, Dr. S. Rajasekaran was Research Scholar in the Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Mumbai 400076, Maharastra, India. He is now Assistant Professor in the Department of Mechanical Engineering, Sri Krishna College of Engineering and Technology, Kuniamuthur Post, Coimbatore 641008, Tamilnadu, India.

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