Forney MIG 180FI, Operating Manual

Page: 17 / 38

17
CHANGE POLARITY
This welder allows you the capability to
change the welding current polarity. You may
select either Straight Flux Core (FCAW)
Polarity or Reverse MIG Polarity (GMAW).
For welding steel with solid wire, stainless
steel, flux cored hardfacing of steel, and sili-
con bronze welding of steel, select DC
Reverse Polarity (DC + MIG). When using
self-shielding, flux-core steel wire, use DC
Straight Polarity (DC - Flux Cored).
Change the polarity of your welder according
to the following procedure steps. Figure 8
shows what the polarity block should look like
for each polarity setting.
WARNING
Electric shock can kill! Always turn the
power OFF and unplug the power cord from
the ac power source before changing polarity.
CAUTION
Do not use a ratchet, crescent or other lever
type wrench to tighten knobs on the polarity
block. The nuts must be hand tightened only.
Too much torque applied to one of the knobs
could cause the knob to break off.
1. Remove the retaining knobs from the +
and - mounting posts on the Gas/No Gas
Board, located just below the drive motor
on the inside of your welder.
A. For Gasless (FCAW) welding, mount
the Ground Clamp ring terminal to the
“+” mounting post and the Torch ring
terminal to the “-” mounting post.
B. For MIG (GMAW) welding, mount the
Ground Clamp ring terminal to the “-”
mounting post and the Torch ring ter-
minal to the “+” mounting post.
See configuration shown in Figure 8.
Figure 8. Changing Polarity
2. Attach the ground clamp to the work
piece, making sure that it is cleaned of
dirt, oil, rust, scale, oxidation, and paint at
the point of connection.
Note: It is best to connect the ground clamp
directly to the work piece and as close to the
weld as possible. If it is impractical to con-
nect the ground clamp directly to the work
piece, connect it to the metal that is securely
attached to the work piece, but not electrical-
ly insulated from it. Make certain this other
metal is of equal or greater thickness than
that of the workpiece.
CAUTION
Risk of electric component damage! If the
ground clamp is being connected to an auto-
mobile or other equipment with on-board
computer systems, solid state electronic con-
trols, solid state sound systems, etc., do not
weld until disconnecting the battery that is
attached to the chassis ground. Failure to do
so may result in electronic component dam-
age.