OM-244 324 Page 22
SECTION 7
−
SELECTING AND PREPARING A TUNGSTEN
FOR DC OR AC WELDING WITH INVERTER MACHINES
gtaw_Inverter_2011-06
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
)
.
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.
Amperage Range - Gas Type
- Polarity
Electrode Diameter
(DCEN)
−
Argon
Direct Current Electrode Negative
(For Use With Mild Or Stainless Steel)
AC
−
Argon
Balance Control @ 65% Electrode Negative
(For Use With Aluminum)
2% Ceria, 1.5% Lanthanum, Or 2% Thorium Alloy Tungstens
.010 in. (1 mm)
Up to 25
Up to 20
.020 in. (1 mm)
15-40
15-35
.040 in. (1 mm)
25-85
20-80
1/16 in. (1.6 mm)
50-160
50-150
3/32 in. (2.4 mm)
130-250
135-235
1/8 in. (3.2 mm)
250-400
225-360
5/32 in. (4.0 mm)
400-500
300-450
3/16 in (4.8 mm)
500-750
400-500
1/4 in. (6.4 mm)
750-1000
600-800
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.
7-2. Preparing Tungsten Electrode For DC Electrode Negative (DCEN) Welding Or AC
Welding With Inverter 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
information. 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
environmentally safe way. Wear proper face, hand, and body protection. Keep flammables away.
Ideal Tungsten Preparation
−
Stable Arc
2-1/2 Times
Electrode Diameter
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
Flat
Diameter of this flat determines amperage
capacity.
4
Straight Ground
Grind lengthwise,
not radial
.
1
3
4
Causes Wandering Arc
2
Wrong Tungsten
Radial Grinding
Preparation
