Section 11 − Selecting And Preparing A Tungsten For Dc Or Ac Welding With Inverter Machines; Selecting Tungsten Electrode (Wear Clean Gloves To Prevent Contamination Of Tungsten); Preparing Tungsten Electrode For Dc Electrode Negative (Dcen) Welding Or Ac Welding With Inverter Machines - Miller Dynasty 200 SD Owner's Manual

SECTION 11 − SELECTING AND PREPARING A TUNGSTEN
FOR DC OR AC WELDING WITH INVERTER MACHINES
!
Whenever possible and practicle, use DC weld output instead of AC weld output.
11-1. Selecting Tungsten Electrode (
Electrode Diameter
2% Ceria (Orange Band), 1.5% Lanthanum (Gray Band), Or 2% Thorium (Red Band) Alloy Tungstens
.010" (1 mm)
.020" (1 mm)
.040" (1 mm)
1/16" (1.6 mm)
3/32" (2.4 mm)
1/8" (3.2 mm)
5/32" (4.0 mm)
3/16" (4.8 mm)
1/4" (6.4 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.
11-2. 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 informa-
tion. Consider using tungsten containing ceria, lanthana, or yttria instead of thoria. Grinding dust from tho-
riated electrodes contains low-level radioactive material. Properly dispose of grinder dust in an environmen-
tally safe way. Wear proper face, hand, and body protection. Keep flammables away.
Radial Grinding
Causes Wandering Arc
Wrong Tungsten Preparation
Om-2240 Page 68
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)
Up to 25
15-40
25-85
50-160
135-235
250-400
400-500
500-750
750-1000
2-1/2 Times
Electrode Diameter
2
4
Ideal Tungsten Preparation − Stable Arc
♦
- Polarity
AC − Argon
Balance Control @ 65% Electrode Negative
(For Use With Aluminum)
Up tp 20
15-35
20-80
50-150
130-250
225-360
300-450
400-500
600-800
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.
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