UNIMIG Cat 2017 low res

TECHNICAL NOTES
TIG
Electrode Included Angle/Taper - DC Welding
Tungsten electrodes for DC welding should be ground longitudinally and concentrically with diamond wheels to a
specific included angle in conjunction with the tip/flat preparation. Different angles produce different arc shapes and
offer different weld penetration capabilities. In general, blunter electrodes that have a larger included angle provide
the following benefits:
• Last Longer
flat spot diameter
• Have better weld penetration
• Have a narrower arc shape
• Can handle more amperage without eroding.
Sharper electrodes with smaller included angle provide:
included angle
• Offer less arc weld
• Have a wider arc
• Have a more consistent arc
The included angle determines weld bead shape and size. Generally, as the included angle increases, penetration
increases and bead width decreases.
Tungsten preparation AC Welding
To obtain full current capacity from a pure or zirconiated tungsten electrode when used with AC current output the
electrode is not ground to a point. The welding during positive polarity melts the point of the tungsten that becomes
rounded. The ball shape formed at the end of the tungsten is desirable because it reduces current rectification and
allows the arc to flow more easily.
balled tip
Arc shape from balled
tungsten AC welding
Arc shape from ground
pointed tungsten DC
welding
Safety with tungsten electrodes
Tungsten welding electrodes should never be manually ground on an abrasive belt or wheel (particularly silicone
carbide). Always use diamond wheels when grinding and cutting tungstens. The risk of injury when hand (manually)
grinding a very hard brittle material like tungsten is quite high. It is important to always follow standard safety
guidelines when operating high speed grinding equipment.
• Wear approved safety glasses
• No loose clothing which may get caught in moving parts
• Wear protective hair covering to contain long hair
• Wear safety shoes with non-slip sole
• A vacuum system is recommended to remove tungsten, especially thorium dust
• Never operate power tools when tired, intoxicated or when taking medication that causes drowsiness
The most common injuries to the manual tungsten electrode grinder are eye and finger related. Holding and grinding
the tungsten electrode by hand has resulted in burned fingers, laceration to fingers and splintered tungsten electrodes
in hand or fingers. Eye injury generally occurs from manually grinding tungsten electrodes without a safety shield or
safety glasses. Small slivers of tungsten electrode may become stuck in the operator’s eye.
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