Lincoln Electric PM 255 specifications Maintenance

	MAINTENANCE	D-1
D-1

SAFETY PRECAUTIONS

WARNING

ELECTRIC SHOCK can kill.

•Have an electrician install and service this equipment.

•Turn the input power off at the fuse box before working on equipment

•Do not touch electrically hot parts.

GENERAL MAINTENANCE

In extremely dusty locations, dirt may clog the air pas- sages 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 mecha- nism. Clean it as necessary by blowing with low pres- sure 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

1.Choose the correct size contact tip for the elec- trode being used (wire size is stenciled on the side of the contact tip) and screw it snugly into the gas diffuser.

2.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 Table D.2 in this section.)

3.If using optional adjustable slip-on nozzles, see Table D.2 in this section.

•Be sure the nozzle insulator is fully screwed onto the gun tube and does not block the gas holes in the diffuser.

•Slip the appropriate gas nozzle onto the nozzle insulator. 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 application.

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

1.Replace worn contact tips as required.

2.Remove spatter from inside of gas nozzle 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 electrode. 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 pres- sure, gently blow out the cable liner from the gas dif- fuser 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 prob- lems are experienced, try liner replacement, and refer to trouble shooting section on rough wire feeding.

PM 255