Section 10 − Selecting And Preparing Atungsten 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 Electric MPi 220P Owner's Manual

SECTION 10 − SELECTING AND PREPARING A
FOR DC OR AC WELDING WITH INVERTER MACHINES
Whenever possible and practical, use DC weld output instead of AC weld output.
10-1. 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
.010 in. (1 mm)
.020 in. (1 mm)
.040 in. (1 mm)
1/16 in. (1.6 mm)
3/32 in. (2.4 mm)
1/8 in. (3.2 mm)
5/32 in. (4.0 mm)
3/16 in (4.8 mm)
1/4 in. (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.

10-2. 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.
Radial Grinding
Causes Wandering Arc
Wrong Tungsten
Preparation
TUNGSTEN
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
Up to 25
15-40
25-85
50-160
130-250
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 to 20
15-35
20-80
50-150
135-235
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.
OM-253 918 Page 65
gtaw_Inverter_2011-06
)