Safety precautions, General maintenance, Drive rolls and guide plates – Lincoln Electric POWER MIG SVM170-A User Manual
Page 30: Contact tip & gas nozzle installation, Gun tubes and nozzles, Gun cable cleaning, Liner removal and replacement, Maintenance, Warning, Caution
D-2
MAINTENANCE
D-2
POWER MIG 255C
SAFETY PRECAUTIONS
• Have a qualified electrician do the
maintenance and troubleshooting
work.
• Disconnect the input power off
using the disconnect switch at the
main input supply before working
inside machine.
• Unplug the power cable if it is connected to a
receptacle.
------------------------------------------------------------------------
GENERAL MAINTENANCE
In extremely dusty locations, dirt may clog the air
passages causing the welder to run hot. Blow dirt out
of the welder with low-pressure air at regular intervals
to eliminate excessive dirt and dust build-up on internal
parts.
The fan motors have sealed ball bearings which
require no service.
DRIVE ROLLS AND GUIDE PLATES
After every coil of wire, inspect the wire drive
mechanism. Clean it as necessary by blowing with low
pressure compressed air. Do not use solvents for
cleaning the idle roll because it may wash the lubricant
out of the bearing.
All drive rolls are stamped with the wire sizes they will
feed. If a wire size other than that stamped on the roll
is used, the drive roll must be changed.
For instructions on replacing or changing drive roll, see
"Wire Drive Rolls" in Operation section.
CONTACT TIP
AND GAS NOZZLE
INSTALLATION
a. Choose the correct size contact tip for the electrode
being used (wire size is stenciled on the side of the
contact tip) and screw it snugly into the gas diffuser.
b. Screw the appropriate fixed gas nozzle fully onto the
diffuser. Either the standard .50" (12.7 mm) flush
nozzle or other optional flush or recessed (spray arc)
nozzle sizes may be used. (See
in this
section.)
c. If using optional adjustable slip-on noz-zles, see
WARNING
1. Be sure the nozzle insulator is fully screwed onto the
gun tube and does not block the gas holes in the dif-
fuser.
2. Slip the appropriate gas nozzle onto the nozzle insu-
lator. Either a standard .50" (12.7 mm) or optional
.62" (15.9 mm) I.D. slip-on gas nozzle may be used
and should be selected based on the welding appli-
cation.
Adjust the gas nozzle as appropriate for the
GMAW process to be used. Typically, the con-
tact tip end should be flush to .12" (3.2 mm)
extended for the short-circuiting transfer process
and .12" (3.2 mm) recessed for spray transfer.
GUN TUBES AND NOZZLES
a. Replace worn contact tips as required.
b. Remove spatter from inside of gas noz-zle and from
tip after each 10 minutes of arc time or as required.
GUN CABLE CLEANING
To help prevent feeding problems, clean cable liner
after using approximately 300 pounds (136 kg) of elec-
trode. Remove the cable from the wire feeder and lay
it out straight on the floor. Remove the contact tip from
the gun. Using an air hose and only partial pressure,
gently blow out the cable liner from the gas diffuser
end.
Excessive pressure at the start may cause the dirt
to form a plug.
Flex the cable over its entire length and again blow out
the cable. Repeat this procedure until no further dirt
comes out. If this has been done and feed problems
are experienced, try liner replacement, and refer to
trouble shooting section on rough wire feeding.
LINER REMOVAL AND REPLACEMENT
NOTE: Changing the liner for a different wire size
requires replacement of the gas diffuser per
to properly secure the different liner
.
CAUTION