Section 9 − Selecting And Preparing Tungsten Electrode For Dc Or Ac Welding; Selecting Tungsten Electrode (Wear Clean Gloves To Prevent Contamination Of Tungsten); Preparing Tungsten Electrode For Welding - Miller Syncrowave 250 DX Manual Del Propietário

SECTION 9 − SELECTING AND PREPARING TUNGSTEN
ELECTRODE FOR DC OR AC WELDING
Y Whenever possible and practical, use DC weld output instead of AC weld output.
9-1. Selecting Tungsten Electrode (
Electrode Diameter
2% Ceria (Orange Band), 1.5% Lanthanum (Gray Band), Or 2% Thorium (Red Band) Alloy Tungstens
.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.

9-2. Preparing Tungsten Electrode For Welding

Y 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 Or AC Welding With Inverter Machines
Radial Grinding
Causes Wandering Arc
Wrong Tungsten Preparation
B. Preparing Tungsten For Conventional AC Welding
OM-363 Page 54
Wear Clean gloves To Prevent Contamination Of Tungsten
Direct Current Electrode Negative
Pure Tungsten (Green Band)
Pure Tungsten Not Recommended
2-1/2 Times
Electrode Diameter
2
4
Ideal Tungsten Preparation − Stable Arc
1 − 1-1/2 Times
Electrode Diameter
1
2
Amperage Range - Gas Type
(DCEN) − Argon
25-85
50-160
135-235
250-400
For DCEN − Argon
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
3 Flat
Diameter of this flat determines amperage
capacity.
4 Straight Ground
Grind lengthwise, not radial.
1 Tungsten Electrode
2 Balled End
Ball end of tungsten by applying AC amper-
age recommended for a given electrode
diameter (see Section 9-1). Let ball on end of
the tungsten take its own shape.
ac/dc_gtaw 2/2000
)
♦
- Polarity
AC − Argon
65% Electrode Negative
20-80
50-150
130-250
225-360
10-60
50-100
100-160
150-210