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7
Stud material
Base metal
Copper plated steel
up to 0.2 C%
Stainless steel
304/316
Al Mg 3
AI Si 12
Al 99,5
Steel up to 0.30 C %
A
A
-
-
-
Galvanized steel
B
B
-
-
-
Stainless steel 304/316
A
A
-
-
-
Al 99,5
-
-
A
B
B
Al Mg 3
-
-
B
A
B
Al Si 12
-
-
B
A
B
High weldability: A Low weldability: B Not weldable: -
Tab. 1
Fig. 3
1
2
3
4
5
5 WELDABILITY OF TYPICAL STUD BOLT/BASE
METAL COM BINATIONS FOR CAPACITOR
DISCHARGE WELDING. (Table 1)
It is important to pay careful attention to the resistance and
deformity at the welding point between the stud bolt and base
metal. In the case of steel, you must pay particular attention
to brittleness. The material and resistance of the stud bolt
have limited tolerance; the carbon content in steel threaded
stud bolts must be < 0.20%.
The surface of the base metal must be clean. Layers
of paint, rust, waste, grease and non-weldable metal
coatings must be removed from the welding area. This
must be done using appropriate means. Base metals with
layers of waste and rust must be cleaned thoroughly
.
6 WELDING
This technology makes it possible to weld stud bolts on
clean, but not oxidized, surfaces of mild steel, galvanized
steel, stainless steel, aluminum and brass.
The rapidity of the process does not alter the surfaces on the
side opposite from the welding. Welding is not possible on
case-hardened steel, oxidized or painted metal.
Before beginning production it is essential to carry out a
few test welds to determine the proper setting of the power
source and gun (spring force), proceeding as follows:
•
Insert the chosen stud bolt in the clamp
X
(previously
adjusted as described in Fig. 2).
•
Arrange the base sheet metal in conditions identical to
those that will be used for the job in terms of thickness,
earth connection area, size of the workpiece, material
quality.
•
The terminals of the earth cable should be placed
symmetrically, and as close as possible to the welding
point.
•
Activate the power source by means of the lighted
switch
E
.
•
Hold the gun and place the stud on the welding spot,
avoiding to give blows, consequently damaging the
striking tip of the stud. Press the trigger
O
and, holding it
pressed, push the gun evenly and not quickly. Once the
right pressure is reached, the weld will be automatically
activated. If the surface of the material on which the stud
bolt is to be welded is fl at, we recommend mounting the
three spacers
Z
after fi rst unscrewing the screws
Y
•
In this case it is recommended to push the gun until the
three spacers are in touch with the piece and then press
the trigger to activate the welding.
These procedures are required to obtain the same
pressure of the stud on the base material and
consequently a higher quality of the weld.
•
The voltage and force values recommended on the display
are intended as a starting point for calculating the correct
power source setting and for calibrating gun force.
These values have been tested on samples of “base
materials” 0.079" (2 mm) thick for steel and stainless steel
and 0.047" (1.2 mm) thick for aluminium.