Guns
Guns are designed to carry current with a specific
duty cycle, just as welding machines are. They are
usually rated by the type of gas that is being used when
they are gas-cooled. Guns that are used for large-
diameter wires are usually water-cooled for a higher duty
cycle. A water-cooled system is shown in Figure 3-25.
If water from a municipal system is used for cooling,
as shown in Figure 3-26, the system requires a filter and
a regulator to match water pressure to the manufacturer’s
requirements.
These additions are needed because municipal water
often contains small particles that could clog gun cooling
passages and ruin the welding torch. For this reason, a
filter must be cleaned or replaced often to prevent
reduced water flow. Manufacturers usually specify
cooling water pressure of no more than 50 psi.
Since municipal water pressure varies, a regulator
must be installed to prevent too much pressure in the
cooling hoses or the gun. Failure to filter the water and
regulate its pressure can result in clogged guns, burst
hoses, and possibly damage to the welding gun.
Spool Guns
Guns of this type are designed for welding
aluminum or other soft alloy wires. All of the types of
guns are rated for a specific duty cycle. They contain a
low voltage motor and drive rollers for moving the
electrode from the spool to the contact tip, Figure 3-27.
Electrode speed is controlled by a rheostat and a trigger
to start and end the sequence. The drive and idler rollers
are of various designs. For this reason, when changing
types of wire, diameters, or replacing parts, the rollers
must be of the same model and manufacturer for the
system to operate as designed.
Gun Parts
As shown in Figure 3-28, the end of the gun has
several components. They are used to receive the liner
assembly, insulate the gas nozzle, and transfer electrical
current to the contact tip and the electrode. These
36 Gas Metal Arc Welding Handbook
Figure 3-23. A new gun liner, ready for installation.
Figure 3-24. Gun liners must fit into the adapter with a specific
extension. Incorrect assembly of this part will cause wire
feeding problems. Always follow the manufacturer’s instructions
when installing liners. (Tweco Products, Inc.)
Pressure
gauge
Regulator
Water in
Water out
Drain
Filter
Figure 3-26. Use of water from municipal systems requires more
equipment to do an efficient job of cooling without wasting water.
Water out
Water cooler
Water in Water
pump
Coolant tank
Pressure
gauge
110V ac
Figure 3-25. This type of a unit is called a closed system. It
eliminates many of the problems associated with water-cooling
the gun.
Contact
tip
Liner extension
Adaptor
Liner lock screw
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Extracted Text (may have errors)


Guns
Guns are designed to carry current with a specific
duty cycle, just as welding machines are. They are
usually rated by the type of gas that is being used when
they are gas-cooled. Guns that are used for large-
diameter wires are usually water-cooled for a higher duty
cycle. A water-cooled system is shown in Figure 3-25.
If water from a municipal system is used for cooling,
as shown in Figure 3-26, the system requires a filter and
a regulator to match water pressure to the manufacturer’s
requirements.
These additions are needed because municipal water
often contains small particles that could clog gun cooling
passages and ruin the welding torch. For this reason, a
filter must be cleaned or replaced often to prevent
reduced water flow. Manufacturers usually specify
cooling water pressure of no more than 50 psi.
Since municipal water pressure varies, a regulator
must be installed to prevent too much pressure in the
cooling hoses or the gun. Failure to filter the water and
regulate its pressure can result in clogged guns, burst
hoses, and possibly damage to the welding gun.
Spool Guns
Guns of this type are designed for welding
aluminum or other soft alloy wires. All of the types of
guns are rated for a specific duty cycle. They contain a
low voltage motor and drive rollers for moving the
electrode from the spool to the contact tip, Figure 3-27.
Electrode speed is controlled by a rheostat and a trigger
to start and end the sequence. The drive and idler rollers
are of various designs. For this reason, when changing
types of wire, diameters, or replacing parts, the rollers
must be of the same model and manufacturer for the
system to operate as designed.
Gun Parts
As shown in Figure 3-28, the end of the gun has
several components. They are used to receive the liner
assembly, insulate the gas nozzle, and transfer electrical
current to the contact tip and the electrode. These
36 Gas Metal Arc Welding Handbook
Figure 3-23. A new gun liner, ready for installation.
Figure 3-24. Gun liners must fit into the adapter with a specific
extension. Incorrect assembly of this part will cause wire
feeding problems. Always follow the manufacturer’s instructions
when installing liners. (Tweco Products, Inc.)
Pressure
gauge
Regulator
Water in
Water out
Drain
Filter
Figure 3-26. Use of water from municipal systems requires more
equipment to do an efficient job of cooling without wasting water.
Water out
Water cooler
Water in Water
pump
Coolant tank
Pressure
gauge
110V ac
Figure 3-25. This type of a unit is called a closed system. It
eliminates many of the problems associated with water-cooling
the gun.
Contact
tip
Liner extension
Adaptor
Liner lock screw

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