Year

1996

Degree Name

Master of Engineering (Hons.)

Department

Department of Mechanical Engineering

Abstract

This Abstract briefly describes a thesis on the development of techniques for the purpose of viewing Gas Metal Arc Welding (GMAW) metal transfer. The thesis also describes an elaborate investigation into the physics associated with metal transfer of this welding process. An understanding of the physical process that is GMAW metal transfer has yet to be fully realised. Many factors are thought to contribute to this phenomenon and a number of theories have been proposed and counter proposed by a multitude of welding researchers. Thus, the thesis is an attempt to better comprehend the process to hopefully lead the way to a complete understanding. The thesis firstly looks into what a weld actually is and presents the associated problems and terminology of welding so the reader may grasp the complex considerations that must be taken into account in order to produce a sound weld. A sound weld is obviously one that exhibits the properties that a designer expects from it during its applied life time. It then moves on to describe the components and materials utilised in such a welding plant. Once these welding fundamentals are shown to provide an understanding of the process, the actual metal transfer is investigated. The metal transfer types are shown together with the forces thought to play an important part in metal removal and transportation to the weld. Various parameters which are known to alter the metal transfer are also presented and discussed. From this one receives a good overall view on what changes metal transfer and also the consequences of the changes. As the title of the thesis suggests, visualisation of the electrode as it melts and travels across the welding arc is a major aim of this work. Visualisation techniques for viewing this are sought and discussed. The necessity of implementing such techniques are pointed out as well. These visualisation methods are then employed in our study. The equipment chosen and used is described in detail and the corresponding results presented. An analysis of GMAW metal transfer theories is undertaken to try and predict what is seen in the pictures produced with the visualisation methods. A comprehensive mathematical analysis is given utilising the 'Static Force Balance Theory' and the 'Mathematica' computing package. The theory is also modified to allow for tapering of the wire electrode. The results are discussed to test the validity of the theory. A discussion on possible improvements and direction for further research is also undertaken. This work is generously funded by the Co-operative Research Centre (CRC) for Materials and Joining as a component of Project 93.12. Project 93.12 is a collaborative research venture in the area of Welding Automation between the Universities of Wollongong and Sydney and the Sydney based CSIRO Division of Applied Physics. Please note that the electrical data acquired and presented in this thesis was obtained from the welding test bed facility at the University of Wollongong whose development is attributed to Professor Michael West and Mr. Lawrence Sanders.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.