Tweco 180 Portable MIG - Manual (Page 44)

FABRICATOR 140, 180 OPERATION
Manual 0-4991 4-8 July 20, 2007
4.09 Establishing the Arc and Making
Weld Beads
Before attempting to weld on a finished piece of work, it
is recommended that practice welds be made on a sample
metal of the same material as that of the finished piece.
The easiest MIG welding procedure for the beginner to
experiment with, is the flat position. This equipment is
capable of flat, vertical and overhead positions.
For practicing MIG welding, secure some pieces of 16 or
18 gauge (0.06” 1.5mm or 0.08” 2.0mm) mild steel plate
6” x 6” (150 x 150mm). Use 0.024” (0.6mm) wire and
CO
2
shielding gas.
4.10 Pre-Weld Procedure
1. Check the OPERATION chapter of this manual for
details on this equipment.
2. Set the welding voltage range switch at position 1
or 2.
3. Set the wire feed speed control to about the 2.5
setting. Readjust as necessary.
4. Adjust the gas flow rate to about 20 cubic feet per
hour (15 - 20 lpm).
5. Review standard safe practice procedures in
ventilation, eye and face protection, fire, compressed
gas and preventative maintenance. See Safety
Instructions and Warnings chapter included in this
manual.
4.11 Welding Procedure
1. Maintain the tip to work distance (stickout) at 5/16”
to 3/8” (8 to 9mm) at all times.
2. For transverse and longitudinal nozzle angles, see
section 4.07 Welding Gun Positions.
3. Hold the gun about 3/8” (9mm) from the work, lower
the helmet by shaking your head and squeeze the
trigger to start the wire feeding, and establish the
arc.
NOTE
Get in the habit of shaking the helmet down,
rather than using the hands. One hand must
hold the gun, and the other is often needed to
hold pieces to be tacked or positioned.
4. Make a single down-hand (pulling) stringer weld
bead.
5. Practice welding beads. Start at one edge and weld
across the plate to the opposite edge.
NOTE
When the equipment is properly adjusted, a
rapidly cracking or hissing sound of the arc is
a good indicator of correct arc length.
6. Practice stopping in the middle of the plate, restarting
into the existing weld crater and continuing the weld
bead across the plate.
NOTE
When the gun trigger is released after welding,
the electrode forms a ball on the end. To the
new operator, this may present a problem in
obtaining the penetration needed at the start
of the next weld. This can be corrected by
cutting the ball off with wire cutters.