OM-251981 Page 12
SECTION 7 − SELECTING AND PREPARING A TUNGSTEN
FOR DC OR AC PHASE MACHINE WELDING
Ref. gtaw_Phase_2018−01
! Whenever possible and practical, use DC weld output instead of AC weld output.
7-1. Selecting Tungsten Electrode (Wear Clean Gloves To Prevent Contamination Of Tungsten)
A. Select Tungsten Electrode
. Not all tungsten electrode manufacturers use the same colors to identify tungsten type. Contact the tungsten electrode manufacturer or refer-
ence the product packaging to identify the tungsten you are using.
Amperage Range - Gas Type♦ - Polarity
Electrode Diameter (DCEN) − Argon
Direct Current Electrode Negative
(For Use With Mild Or Stainless Steel)
AC − Argon
Unbalanced Wave
(For Use With Aluminum)
2% Ceria Or 1.5% Lanthanum
.040” (1 mm) 15-80 15-80
1/16” (1.6 mm) 70-150 70-150
3/32” (2.4 mm) 150-250 140-235
1/8” (3.2 mm) 250-400 225-325
Pure Tungsten
.040” (1 mm) Pure Tungsten Not Recommended
For DCEN − Argon
10-60
1/16” (1.6 mm) 50-100
3/32” (2.4 mm) 100-160
1/8” (3.2 mm) 150-210
♦Typical argon shielding gas flow rates are 10 to 25 CFH (cubic feet per hour).
Figures listed are a guide and are a composite of recommendations from American Welding Society (AWS).
7-2. Preparing Tungsten Electrode For Welding With Phase Control Machines
! Grinding the tungsten electrode produces dust and flying sparks which can cause injury and start fires. Use
local exhaust (forced ventilation) at the grinder or wear an approved respirator. Read MSDS for safety infor-
mation. Consider using tungsten containing ceria, lanthana, or yttria instead of thoria. Grinding dust from
thoriated electrodes contains low-level radioactive material. Properly dispose of grinder dust in an environ-
mentally safe way. Wear proper face, hand, and body protection. Keep flammables away.
A. Preparing Tungsten For DC Electrode Negative (DCEN) Welding
1 Grinding Wheel
Grind end of tungsten on fine grit, hard
abrasive wheel before welding. Do not use
wheel for other jobs or tungsten can become
contaminated causing lower weld quality.
2 Tungsten Electrode
A 2% ceriated tungsten is recommended.
3 Ideal Grind Angle Range: 15° to 30°
. 30 degrees is the recommended elec-
trode grind angle.
4 Straight Ground
Grind lengthwise, not radial.
1 Tungsten Electrode
A pure tungsten is recommended..
2 Balled End
Ball end of tungsten by applying AC amper-
age recommended for a given electrode
diameter (see Section 7-1). Let ball on end of
the tungsten take its own shape.
B. Preparing Tungsten For AC Welding
1 − 1-1/2 Times
2
Electrode Diameter
Causes Wandering Arc
1
Wrong Tungsten Preparation
Radial Grinding
Ideal Tungsten Preparation − Stable Arc
1
3
2
15° to 30°
4
1-1/2 To 4 Times
Electrode Diameter
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