Nelweld Operations and Service Manual
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2.0 INTRODUCTION TO STUD WELDING
2.1 Processes
There are two main stud welding processes that
can be accomplished by the Nelweld series of
power supplies:
•
Drawn Arc (Electric Arc)
•
Short Cycle/Gas Arc
Each process is a bit different, and is intended for
different applications. Thus, it is important to
choose the correct process for your needs.
2.2 Principles of the Drawn Arc (Electric
Arc) Welding Process
Electric Arc stud welding involves the same
electrical,
mechanical,
and
metallurgical
principles as any other arc welding process. In
stud welding, the power source and stud welding
control system are set to control the amperage
flow (current) and the duration (time) of arcing.
The weld gun has a trigger circuit to initiate the
weld and a lifting mechanism to draw the stud
away
from the base material and initiate the
welding arc. The gun accessories include a chuck
to hold the stud and a ferrule grip to hold the
ceramic ferrule, which is also called an arc shield
.
Figure 2-1:
Stud welding sequence of operations
The sequence of operations to make a stud weld
are as follows:
•
A stud and ferrule are loaded into the chuck
and grip.
•
The gun is positioned against the base
material taking up the
plunge
, or stud length
available for burn off against the gun spring
pressure. (Step A)
•
The trigger is then depressed to start the fully
controlled automatic sequence. This sequence
consists of initiating the weld current, lifting
the stud to create an arc by energizing the gun
solenoid (Step B), timing out the weld time,
plunging the stud by de-energizing the gun
solenoid (Step C), and turning off the weld
current at the end of the weld cycle. (Step D)
The fasteners for electric arc stud welding have a
special shape and flux on the end of the stud that
is to be welded. This flux initiates, improves
starting, and stabilizes the welding arc, and
deoxidizes the molten weld metal for a sound,
void free weld zone producing a full penetration
weld which is strong enough to develop the full
stud strength.
The ceramic ferrule confines the weld arc and
heat to a specific area of the base material and
holds the molten metal in place to provide the
uniform weld flash. The term flash is used
instead of fillet since the weld zone is made up of
a mixture of material melted from the end of the
stud and from the base plate material rather than
from a filler material as is used in other welding
processes.
2.3 Principles of the Short Cycle/Gas Arc
Welding Process
In the Short Cycle stud welding process, a
welding power source provides a continuous
welding current. Both welding current and time
are important factors when welding using the
Short Cycle process, as in the Electric Arc
process. Typically, the welding time varies from
10-100 milliseconds (0.01 – 0.1 seconds), and the
current varies from 300 to 1800A, depending on
the size of the stud. Shielding gas may be used as
a welding aid in place of ceramic ferrules.
The welding cycle proceeds in a manner that is
very similar to the Electric Arc process. However,
unlike the Electric Arc process, the studs used do
not have a flux load in the tip of the stud. The
speed of the process renders a flux load obsolete.
A
B
C
D
Summary of Contents for Nelweld 4000
Page 58: ...Nelweld Operations and Service Manual 58 7 5 Declaration of Conformity...
Page 61: ...Nelweld Operations and Service Manual 61 8 2 Base and Side Cabinet Section...
Page 65: ...Nelweld Operations and Service Manual 65 8 4 Rear Cabinet Section...
Page 67: ...Nelweld Operations and Service Manual 67 8 5 Wiring Diagram...
