Lincoln Electric IM884 PRO-MIG 140 - Manual (Page 17)

B-5 OPERATION B-5
FIGURE B.6
Making A Weld
1. See “Process Guidelines” in this section for selec-
tion of welding wire and shielding gas and for
range of metal thicknesses that can be welded.
2. See the Application chart on the inside of the wire
feed compartment door for information on setting
the Pro-MIG 140 controls. Refer to Table B.1 for
aluminum and stainless wire.
3. Set the Voltage (“V”) and Wire Speed (“olo’”) con-
trols to the settings suggested for the welding wire
and base metal thickness being used, refer to
Applications chart on the inside of the wire drive
compartment door.
4. Check that the polarity is correct for the welding
wire being used and that the gas supply, if
required, is turned on.
5. When using Innershield electrode, remove the gas
nozzle and install the gasless nozzle. This will
improve visibility of the arc and protect the gas dif-
fuser from weld spatter. Refer to the MAINTE-
NANCE section for details on nozzle replacement.
FIGURE B.7
6. Refer to Figure B.7. Connect work clamp to metal
to be welded. Work clamp must make good elec-
trical contact to the workpiece. The workpiece
must also be grounded as stated in “Arc Welding
Safety Precautions” in the beginning of this manu-
al.
7. Position gun over joint. End of wire may be lightly
touching the work.
8. Place hand shield in front of face, close gun trig-
ger, and begin welding. Hold the gun so the con-
tact tip to work distance is about 3/8 inch (10 mm).
9. To stop welding, release the gun trigger and then
pull the gun away from the work after the arc goes
out.
10. When no more welding is to be done, close valve
on gas cylinder (if used), momentarily operate gun
trigger to release gas pressure, and turn off the
Pro-MIG 140.
Cleaning Tip And Nozzle
Clean the contact tip and nozzle to avoid arc bridging
between the nozzle and contact tip which can result in
a shorted nozzle, poor welds and an overheated gun.
Hint: Anti-stick spray or gel, available from a welding
supply distributor, may reduce buildup and aid in spat-
ter removal.
PROCESS GUIDELINES
The Pro-MIG 140 can be used for welding mild steel
using the GMAW, single pass process which requires
a supply of shielding gas or it can be used for the self-
shielded, Innershield® process (FCAW).
The recommended gases and electrodes for GMAW
are welding grade CO2 gas or an argon-CO2 blended
gas (75 to 80% argon and 25 to 20% CO2) and .025"
(0.6 mm) diameter Lincoln Super Arc L-56 mild-steel
welding wire, supplied on 12-1/2 lb (5.7 kg) spools.
The recommended electrode for the self-shielded
process is .035” (0.9 mm) diameter Lincoln
Innershield® NR-211-MP. This electrode can be used
for all position welding of 20 gauge (1.0 mm) through
5/16" (8 mm) steel. Thickness of 1/4" (6 mm) and
5/16" (8 mm) require multiple passes. This wire can
also be used for the welding of galvanized coated
sheet metal.
Pro-MIG 140
Contact Tip
Wire Electrode
WORKPIECE
GUN CABLE
ARC
WORK CLAMP
Pro-MIG™ 140
3/8"– 1/2"(10-13mm) Contact
Tip to Work Distance(CTWD)