How to "Correctly" Grind, Cut & Prepare Tungsten Welding Electrodes (11 pages)
step ii: tungsten electrode geometry & grinding
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4. STEP II: TUNGSTEN ELECTRODE GEOMETRY & GRINDING
TUNGSTEN ELECTRODE GEOMETRY
The shape of the tungsten electrode tip is an important process variable in GTAW. Tungsten electrodes
may be used with a variety of tip preparations. In AC welding, pure or Zirconiated tungsten electrodes
melt to form a hemispherical balled end. For DC welding, Thoriated, Ceriated, or Lanthanated tungsten
electrodes are usually used. For the latter, the end is typically ground to a specific included angle, often
with a truncated end. Various electrode tip geometries affect the weld bead shape and size. In general, as
the included angle increases, the weld penetration increases and the width of the weld bead decreases.
Although small diameter electrodes may be used with a square end preparation for DCEN (Direct Current
Electrode Negative) welding, conical tips provide improved welding performance.
Regardless of the electrode tip geometry selected, it is important that consistent electrode geometry be
used once a welding procedure is established. Changes in electrode geometry can significantly influence
the weld bead shape and size; therefore, electrode tip configuration is a welding variable that should be
studied during the welding procedure development.
TUNGSTEN ELECTRODE GRINDING
To produce optimum arc stability, diamond grinding of tungsten electrodes should be done with the axis
of the electrode perpendicular to the axis of the grinding wheel. The diamond grinding wheel should be
reserved for grinding only tungsten to eliminate possible contamination of the tungsten tip with foreign
matter during the grinding operation. An exhaust system should be used when grinding Thoriated
electrodes to remove the grinding dust from the work area.