Operation; Electrodes And Equipment; Avoiding Wire Feeding Problems - Lincoln Electric MAGNUM PRO 400A Series Operator's Manual

MAGNUM ® PRO WATER-COOLED 400A & 500A GUNS

OPERATION

Do not attempt to use this equipment until you
have thoroughly read all operating and mainte-
nance manuals supplied with your machine. They
include important safety precautions, detailed
engine starting, operating and maintenance
instructions and parts lists.
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts such
as output terminals or
• Insulate yourself from the work and
ground.
• Always wear dry insulating gloves.
FUMES AND GASES can be dan-
gerous.
• Keep your head out of fumes.
• Use ventilation or exhaust to remove
fumes from breathing zone.
WELDING SPARKS can cause fire
or explosion.
• Keep flammable material away.
ARC RAYS can burn.
• Wear eye, ear and body protection.
Only qualified personnel should operate this
equipment.
The wire feeder drive roll pressure should be set to a minimum to
prevent wire from coming thru the cable when a wire feed stop
occurs. The ideal drive roll pressure is set so the drive rolls will
slip when the electrode is slightly wavy after a wire feed stop.

electroDes anD equipMent

The Magnum PRO 400A & 500A Water-Cooled guns and cables
have been designed for use with Lincoln L-50 and Super Arc L-56,
solid steel wire electrodes for the GMAW process and Lincoln
Outershield ® cored electrodes for the gas-shielded FCAW process.
Refer to the appropriate Lincoln Process and Procedure Guidelines
for the electrode used for information on recommended electrical
and visible stickouts.
internal wiring.
MaKinG a WelD
Note: Water cooled guns will have a higher voltage drop along the
length of the cable than air cooled guns. To compensate for the
higher voltage drop, the following table is a guide line to
determine how much the welding voltage should be increased.
Welding Voltage
Increase For
Welding Magnum PRO 400A
Current Water-Cooled Gun
Compared to
MAGNUM
200 amperes 0.5 volts
300 amperes 1.0 volts
400 amperes 1.5 volts
500 amperes
The final voltage setting must be determined by the arc charac-
teristics that are required for the welding process.
a) Check that the welding power source is on and that the
shielding gas supply is set for the proper flow rate.
b) Position electrode over joint. The end of the electrode should
be slightly off the work.
c) Lower your welding helmet, close the gun trigger, and begin
welding. Hold the gun so the contact tip to work distance
gives the correct electrical stickout as required for the
procedure being used.
d) To stop welding, release the gun trigger and then pull the gun
away from the work after the arc goes out.

avoiDinG Wire FeeDinG probleMs

Wire feeding problems can be avoided by observing the following
gun handling procedures:
a) If a 'burn back' or wire feed stop occurs, release the trigger
immediately. Remove the contact tip, free the wire and clean
or replace the tip as necessary. If the wire has been scored
by the feed rolls, discard the damaged section of the wire.
This is necessary because the damaged wire could jam in the
contact tip and cause another burn back.
b) Do not kink or pull cable around sharp corners.
c) Keep the electrode cable as straight as possible when welding
or loading electrode through cable.
d) Avoid wrapping excess cable around handle or front of wire
feeder.
e) Do not allow dolly wheels or trucks to run over cables.
f) Keep cable clean by following maintenance instructions.
g) Use only clean, rust-free electrode. The Lincoln electrodes
have proper surface lubrication.
h) Replace contact tip when the arc starts to become unstable or
the contact tip end is fused or deformed.
i) When using aluminum electrodes, 10 ft. Maximum cable
length is recommenced. If longer cable lengths are used,
cable should be kept as straight as possible.
B-1
OPERATION
Welding Voltage
Increase For
Magnum PRO 500A
Water-Cooled Gun
Compared to
® ®
400 MAGNUM 550
0.5 volts
0.7 volts
0.9 volts
—- 1.2 volts