they must be kept dry to protect the electrical compo-
nents within the feeder. Electrical malfunctions should be
checked only by a skilled electrician. The printed circuit
boards (if the feeder is so equipped) should be replaced
only with factory authorized parts obtained from the
welding supplier.
The major problems will be found in the drive roll
system and the guides to and from the rollers. Worn
equipment will cause many problems in the system.
Inspect the guides and rollers often and replace when
worn. If you have feeding problems, the wire feed
mechanism is most likely where the problem exists. To
determine if the feeder is at fault, disconnect the gun
cable and run the wire through the feeder only. The wire
should run through smoothly. If the feeder is operating
satisfactorily, connect the gun and cable to the feeder.
Operate the feeder with the gun and cable attached. If the
fault remains, the problem is in the gun and cable
assembly. Be sure you know where a problem is before
you try to repair it.
Cables and Guns
Cables
Cables are used to carry electrical current, shielding
gas, and welding wire to the gun. In some cases, the cable
includes tubing to carry cooling water to and from the
gun. Some cables will also include a circuit wire from the
switch to the machine contactor, which is used to start
and stop the weld operation. The cables are usually made
in specified lengths. Some may be connected to other
sections to lengthen the cable.
Where the cable attaches to the wire feeder, special
adapters are necessary. As a general rule, each type of
gun requires an adapter that is made by the gun manu-
facturer. A cable adapter is shown in Figure 3-22.
To protect the cables and guns from wear as the wire
passes through them, liners are installed. In some cases,
special liners are installed in the gun. Manufacturers will
specify which liner must be used with each type and size
of wire. Some wires may require use of a special lining
material, such as
Teflon®
or nylon. The cable liner
shown in Figure 3-23 is always installed into the gun
cable from the feeder end and secured at the welding tip
end. See Figure 3-24. Since each manufacturer makes
guns to a specific design, the liners are not interchange-
able. When changing spools and types of wire, always
blow out the liner with clean, dry compressed air to
remove any residue from the previous wire.
Chapter 3 Equipment Set-up and Control 35
Figure 3-20. “Birdnesting” of the wire is often caused by
improper operation of the wire feed system. Check the guides,
rollers, and tension to find the problem and correct it.
Figure 3-21. A wire wiper can be assembled from a clothespin
and a piece of felt. Commercial fluids may be used in the wiper
material. (Ferro-Slick/Lube-Matic)
Figure 3-22. Adapters can be used to connect different types
of guns to a wire feeder.
Brake Piece of felt Clothespin
Gas
solenoid
Gun adapter