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SECTION 6 − SELECTING AND PREPARING A TUNGSTEN
!
Whenever possible and practical, use DC weld output instead of AC weld output.
6-1. Selecting Tungsten Electrode (
.
Not all tungsten electrode manufacturers use the same colors to identify tungsten type. Contact the tungsten electrode manufacturer or reference
the product packaging to identify the tungsten you are using.
Electrode Diameter
.040" (1 mm)
1/16" (1.6 mm)
3/32" (2.4 mm)
1/8" (3.2 mm)
.040" (1 mm)
1/16" (1.6 mm)
3/32" (2.4 mm)
1/8" (3.2 mm)
♦
Typical argon shielding gas flow rates are 11 to 35 cfh (cubic feet per hour).
Figures listed are a guide and are a composite of recommendations from American Welding Society (AWS) and electrode manufacturers.
6-2. 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
Radial Grinding
Causes Wandering Arc
Wrong Tungsten Preparation
B. Preparing Tungsten For AC Welding
FOR DC OR AC WELDING
Wear Clean Gloves To Prevent Contamination Of Tungsten
Amperage Range - Gas Type
(DCEN) − Argon
Direct Current Electrode Negative
(For Use With Mild Or Stainless Steel)
2% Ceria, 1.5% Lanthanum, Or 2% Thorium Alloy Tungstens
25-85
50-160
130-250
250-400
Pure Tungsten
Pure Tungsten Not Recommended
For DCEN − Argon
2-1/2 Times
Electrode Diameter
2
4
Ideal Tungsten Preparation − Stable Arc
1 − 1-1/2 Times
Electrode Diameter
1
2
♦
- Polarity
AC − Argon
Balance Control @ 65% Electrode Negative
(For Use With Aluminum)
20-80
50-150
135-235
225-360
10-60
50-100
100-160
150-210
1
Grinding Wheel
Grind end of tungsten on fine grit, hard
3
abrasive wheel before welding. Do not use
wheel for other jobs or tungsten can become
contaminated causing lower weld quality.
1
2
Tungsten Electrode
A 2% ceriated tungsten is recommended.
3
Flat
Diameter of this flat determines amperage
capacity.
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 6-1). Let ball on end of
the tungsten take its own shape.
OM-225 430 Page 13
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