30 |
5. The amount of protective gas - it has to be adjust-
ed according to the type of welding or according to
the size of gas hose. After finishing the welding gas
must flow sufficiently long to protect material and
tungsten electrode against oxidation.
Typical TIG welding errors and their impact on weld
quality
The welding current is too -
Low:
unstable welding arc
High:
Tungsten electrode tip breaks lead to turbulent
arcing.
Further, mistakes may be caused by poor welding torch
guidance and poor addition of additive material.
Basic rules for welding by MMA
Switch the machine to MMA mode - coated electrode.
Table 6 lists the general values for the choice of the
electrode, depending on its diameter and the thickness
of the base material. These data are not absolute and
are informative only. For exact selection, follow the in
-
structions provided by the manufacturer of the electro
-
des. The current used depends on the position of the
welding and the joint type and increases according to
the thickness and dimensions of the part.
Table 6
Strength of welded
material (mm)
Diameter of the
Electrode
1,5 - 3
2
3 - 5
2.5
5 - 12
3.25
> 12
4
Table 7: Setting the welding current for the given
electrode diameter
Diameter of the
Electrode
Welding Current
(A)
1.6
30 - 60
2
40 - 75
2.5
60 - 110
3.25
95 - 140
4
140 - 190
5
190 - 240
6
220 - 330
The approximate indication of the average current
used for welding with ordinary steel electrodes is gi
-
ven by the following formula:
I = 50 x (Øe – 1)
where: I = the intensity of the welding current
e = the diameter of the electrode
Example for an electrode with a diameter of 4 mm:
I = 50 x (4 - 1) = 50 x 3 = 150 A
Correct electrode holding during welding
45°
β
45° +70°
Pic. 8
Preparation of basic material:
Table 8 lists the material preparation values. Specify
the dimensions as shown in pic. 9.
a
s
α
d
Pic. 9
Table 8
s (mm)
a (mm)
d (mm)
α (°)
0 - 3
0
0
0
3 - 6
0
s/2 (max)
0
3 - 12
0 - 1.5
0 - 2
60
Warning about possible problems and their
remedy
The extension cord and welding cables are considered
the most common cause of the problem.
If you have
any problems, follow these steps:
• Check the value of the supplied mains voltage.
• Make sure that the power cord is fully connected to
the power outlet and the main power switch.
• Make sure the fuses or the circuit breakers are OK.
If you are using the extension cable, check its length,
cross-section and connection.
EN
