CEA Rainbow 180 Manuel D'instructions page 11

PART TO BE WELDED
The part to be welded must always be connected to earth in or-
der to reduce electromagnetic emission. Much attention must
be afforded so that the earth connection of the part to be weld-
ed 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 di-
rect 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 com-
pliance with the national 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
values of current to use are shown in the table with the respec-
tive 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 electrode manufacturer.
The current to be used depends on the welding positions and
the type of joint, and it increases according to the thickness and
dimensions of the part.
The current intensity to be used for the different types of weld-
ing, 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 fol-
lowing 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
elevated 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 cylin-
der 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 posi-
tion.
4) Start the welding machine by selecting Pos. 1 on the line
switch (Pos. 1, Fig. A).
5) The green LED (Pos. 5, Fig. A) shows that the power sup-
ply to the welding machine is on, and it is ready to work.
6) Adjust the gas flow by manually turning the valve on the
TIG torch.
7) The "Lift" function strikes the arc when the TIG torch elec-
trode comes into contact with the workpiece and is then
removed (see Fig. D).
8) Carry out TIG welding.
FIG. C
FIG. D
PART TO BE WELDED
The part to be welded must always be connected to earth in or-
der to reduce electromagnetic emission. Much attention must
be afforded so that the earth connection of the part to be weld-
ed 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 di-
rect 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 com-
pliance with the national regulations.
11
2000HA44
2000HA39