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The importance of electrode preparation as one of the key parameters in repeatable and high quality TIG (GTAW) welding is often overlooked. This article outlines some of the problems encountered by manual electrode grinding and examines the advantages of mechanizing the process.
A major factor, arguably the most important, in fusion welding is consistency of metal deposition. Although weld bead geometry and metallurgy are influenced by many factors, the majority of these are now controlled remote from, and independent of, the welder.
They can include joint design and preparation of component parts, selection of filler metal, welding current, and welding power source. The operator may have control over weld speed, but even this is delegated to mechanical drives when using automatic processes.
With the development of formal welding procedures and the ready availability of programmable mechanized welding systems, one might think the contemporary welder has little to do other than keep an eye open for system malfunctions.
Such an apparent aphorism is flawed. Although considerable time and effort may have been dedicated to developing welding procedures in an attempt to remove variables from the welding process, rarely is there any reference to electrode preparation or even to electrode selection.
Electrode Materials
A wide range of electrode compositions is now available, and their selection should be in accord with previous experience and published information.
Various additions have been made to pure tungsten to improve welding performance. These include oxides based on the rare earth metals cerium, lanthanum, yttrium and thorium. Thoria-containing electrodes introduce a potential health hazard associated with ingesting the dust generated during grinding.
Electrode Tip Geometry
The essential...