5
between the part and the earth shaft. In those countries in which
such a connection is not allowed, connect the part to be welded
to earth using suitable capacitors, in compliance with the nation-
al regulations.
WELDING PARAMETERS
Table 3 shows some general indications for the choice of elec-
trode, based on the thickness of the parts to be welded. The val-
ues of current to use are shown in the table with the respective
electrodes for the welding of common steels and low-grade alloys.
These data have no absolute value and are indicative data only.
For a precise choice follow the instructions provided by the elec-
trode manufacturer.
The current to be used depends on the welding positions and the
type of joint, and it increases according to the thickness and di-
mensions of the part.
The current intensity to be used for the different types of welding,
within the field of regulation shown in table 4 is:
•
High for plane, frontal plane and vertical upwards welding.
•
Medium for overhead welding.
•
Low for vertical downwards welding and for joining small pre-
heated pieces.
A fairly approximate indication of the average current to use in
the welding of electrodes for ordinary steel is given by the follow-
ing formula:
I = 50 × (Øe – 1)
Where:
I = intensity of the welding current
Øe = electrode diameter
Example:
For electrode diameter 4 mm
I = 50 × (4 – 1) = 50 × 3 = 150A
TIG welding (Fig. C)
TIG welding melts the metal of the workpiece, using an arc struck
by a tungsten electrode.
The fusion bath and the electrode are protected by gas (Argon).
This type of welding is used to weld thin sheet metal or when el-
evated quality is required.
1) Connecting the welding cables:
•
Connect one end of the gas hose to the gas connecter on
the TIG torch and the other end to the Argon cylinder and
open it.
•
With the machine switched off:
- Connect the earth cable to the snap-on connector marked
+ (positive).
- Connect the relative earth clamp to the workpiece or to the
workpiece support in an area free of rust, paint, grease,
etc..
- Connect the TIG torch power cable to the snap-on con-
nector marked - (negative).
2) Adjust the welding current using the potentiometer (Pos. 4,
Fig. A).
3) Turn the process selector (Pos. 6, Fig. A) to the TIG position.
4) Start the welding power source by selecting Pos. 1 on the line
switch (Pos. 1, Fig. A).
5) The two-tone LED (Pos 5, Fig A) will turn GREEN, which
means that the VRD function is active.
6) Adjust the gas flow by manually turning the valve on the TIG
torch.
7) To “deactivate” the VRD device and therefore start to weld, fol-
low this simple procedure: First touch the workpiece with the
electrode, then detach and ignite (see Fig D).
8) Carry out TIG welding. During welding the VRD LED may turn
RED, which does not indicate any malfunction on the welding
power source, but that the VRD device has been deactivated
to allow welding.
PART TO BE WELDED
The part to be welded must always be connected to earth in order
to reduce electromagnetic emission. Much attention must be af-
forded so that the earth connection of the part to be welded does
not increase the risk of accident to the user or the risk of damage
to other electric equipment. When it is necessary to connect the
part to be welded to earth, you should make a direct connection
between the part and the earth shaft. In those countries in which
such a connection is not allowed, connect the part to be welded
to earth using suitable capacitors, in compliance with the nation-
al regulations.
2000HA39
FIG. D
FIG. C
