How to "Correctly" Grind, Cut & Prepare Tungsten Welding Electrodes (11 pages)

selecting the best tungsten composition

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DIAMOND GROUND PRODUCTS

“The Tungsten Electrode Experts”

2550 Azurite Circle Newbury Park, CA 91320 PH: 805.498.3837 FX: 805.498.9347 Web:

www.DiamondGround.com

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6. SELECTING THE BEST TUNGSTEN COMPOSITION

To correctly prepare your tungsten electrode for welding you must first select the composition and
diameter best suited for your application. Below listed are the 5 most commonly produced tungsten
welding electrodes for TIG DC, TIG-AC, and Plasma welding:

PURE TUNGSTEN (EWP Classification - Green Stripe)



2% CERIATED TUNGSTEN (EWCe Classification - Orange Stripe)



1% ZIRCONIATED TUNGSTEN (EWZr Classified - Brown Stripe)



1% THORIATED TUNGSTEN (EWTh-1 Classification - Yellow Stripe)



2% THORIATED TUNGSTEN (EWTh-2 Classification - Red Stripe)

All values are based on the use of argon as the shielding gas. Other current values may be employed
depending on the shielding, gas, type of equipment, and application. Electrodes are produced with either
a clean finish or ground finish. Electrodes with a clean finish have been chemically cleaned to remove
surface impurities after the forming operation. Those with a ground finish have been centerless ground to
remove surface imperfections.


ELECTRODE SIZES AND CURRENT CAPACITIES

Tungsten and Thoriated tungsten electrode sizes and current ranges are listed in Table 1.2, along with
shield-gas cup diameters recommended for use with different types of welding power. This table provides
a useful guide for selecting the correct electrode for specific applications involving different current levels
and power supplies. Current levels in excess of those recommended for a given electrode size and tip
configuration will cause the tungsten to erode or melt. Tungsten particles may fall into the weld pool and
become defects in the weld joint. Current too low for a specific electrode diameter can cause arc
instability. Direct current with the electrode positive requires a much larger diameter to support a given
level of current because the tip is not cooled by the evaporation of electrons but heated by their impact. In
general, a given electrode diameter on DCEP would be expected to handle only 10 percent of the current
possible with the electrode negative. With alternating current, the tip is cooled during the electrode
negative cycle and heated when positive. Therefore, the current carrying capacity of an electrode on AC
is between that of DCEN and DCEP. In general, it is about 50 percent less than that of DCEN.

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