The heat necessary for coalescence is produced
23. Do not allow hose to come in contact with
by an electric arc that is drawn between the metal
oil or grease; these rot the rubber and cause a
stud (held in the gun) and the other workpiece part.
When the stud and the other piece have reached the
required temperature, they are brought together
24. Be sure the connections between the
under slight pressure from a spring in the gun. The
regulators, adaptors, and cylinder valves are gas
process requires relatively little skill, since many
tight. Test them with soapy water under gas
factors are controlled automatically. When you
press the trigger of the gun, the arc is established
and controlled, the welding time is controlled, and
25. When welding is to be stopped for an
the stud is plunged against the plate at the proper
extended l e n g t h o f t i m e , r e l e a s e t h e
time and held in place until the weld is completed.
pressure-adjusting screws of the regulators.
If you have problems getting sound welds, check
26. When welding is to be stopped for a longer
these three common errors made while stud
time, close the cylinder valves and then release all
gas pressure from the regulators and hose.
27. If the equipment is to be taken down, close
Improper amperage supplied to the stud gun
the cylinder valves, make certain that all gas
from the power source. Welding of 5/8-inch
pressures are released from the regulators and hose,
studs requires amperage settings of up to
and see that the pressure-adjusting screws are
750 amps. Most stud guns require special
turned in the counterclockwise direction.
power sources that can deliver such high
amperages. Most shop welding machines
28. Use flat black paint on bulkheads and
cannot deliver e n o u g h amperages to
overhead of weld areas to reduce ultraviolet light
properly weld studs over l/4 inch.
reflected from GTA or GMA welding areas.
Improper welding time selected. Consult
owner's manual or process instruction for
OTHER ELECTRIC WELDING
proper weld time selection.
Base metal not cleaned properly. Remove
In addition to the shielded metal-arc process
all rust, paint, oil, or grease from weld area
and the two shielded gas processes already described
and grind to bare metal.
in this chapter, there are two other welding
processes that you should know about. These are
stud welding and resistance welding. Each of these
processes is summarized briefly in the following
Of all the electric welding processes discussed in
this chapter, resistance welding is the only one that
cannot be considered as an arc process. Electrodes
are used in resistance welding, but they do not
create an arc. Instead, the electrodes (there are
Stud welding is a relatively simple electric
usually two of them) are pressed against the
welding-arc process that is used to end-weld studs to
workpieces. Current is applied, and the heat
plate or other pieces. Stud welding was first
necessary for coalescence is produced by the
developed to fasten wooden decking to steel plates,
resistance of the workpieces to the flow of a
but it has become widely used for a variety of other
low-voltage, high-amperage current.
applications. The equipment required for stud
welding includes (1) a stud welding gun, (2) a timing
Among the processes included in the resistance
device to control the time of current flow, (3) a
welding group are spot welding, seam welding, and
source of dc power for welding, and (4) a supply of
projection welding. The discussion here is confined
specially designed metal studs and ferrules. A
to spot welding, since this is the only type of
typical portable stud welding gun is shown in figure
resistance welding that is commonly used aboard
10-71. Figure 10-72 shows the connections between
ship. Figure 10-73 shows a type of spot welding
the various units in the system.