Tweco 95 S Thermal Arc(Nov2010) - Manual (Page 36)

THERMAL ARC 95 S OPERATION
Manual 0-5175 4-8 Operation
of the fillet. The electrode needs to be about 10°
from the horizontal to enable a good bead to be
deposited. Refer Figure 4-16. Use a short arc, and
do not attempt to weave on the first run. When
the first run has been completed de-slag the weld
deposit and begin the second run at the bottom.
This time a slight weaving motion is necessary
to cover the first run and obtain good fusion at
the edges. At the completion of each side motion,
pause for a moment to allow weld metal to build
up at the edges, otherwise undercut will form and
too much metal will accumulate in the centre of the
weld. Figure 4-17 illustrates multi-run technique
and Figure 4-18 shows the effects of pausing at
the edge of weave and of weaving too rapidly.
Art # A-07701
Figure 4-16: Single run vertical fillet weld
Art # A-07702
Figure 4-17: Multi run vertical fillet weld
Art # A-07703
Figure 4-18: Examples of vertical fillet welds
2. Vertical Down
The E7014 electrode makes welding in this
position particularly easy. Use a 1/8" (3.2mm)
electrode at 120 amps. The tip of the electrode is
held in light contact with the work and the speed
of downward travel is regulated so that the tip of
the electrode just keeps ahead of the slag. The
electrode should point upwards at an angle of
about 45°.
3. Overhead Welds
Apart from the rather awkward position necessary,
overhead welding is not much more difficult
that downhand welding. Set up a specimen for
overhead welding by first tacking a length of angle
iron at right angles to another piece of angle iron
or a length of waste pipe. Then tack this to the
work bench or hold in a vice so that the specimen
is positioned in the overhead position as shown
in the sketch. The electrode is held at 45° to
the horizontal and tilted 10° in the line of travel
(Figure 4-19). The tip of the electrode may be
touched lightly on the metal, which helps to give a
steady run. A weave technique is not advisable for
overhead fillet welds. Use a 1/8" (3.2mm) E6012
electrode at 120 amps, and deposit the first run
by simply drawing the electrode along at a steady
rate. You will notice that the weld deposit is rather
convex, due to the effect of gravity before the
metal freezes.
Art # A-07704
Figure 4-19: Overhead fillet weld
4.19 Distortion
Distortion in some degree is present in all forms of
welding. In many cases it is so small that it is barely
perceptible, but in other cases allowance has to be made
before welding commences for the distortion that will
subsequently occur. The study of distortion is so complex
that only a brief outline can be attempted hear.