Tweco 170 HF Weldskill - Manual (Page 32)

WELDSKILL 170 HF INVERTER
4-10 April 23, 2008
C. Vertical Welds
1. Vertical Up
Tack weld a three feet length of angle iron to
your work bench in an upright position. Use a
3.2mm Ferrocraft 21 electrode and set the
current at 100 amps. Make yourself
comfortable on a seat in front of the job and
strike the arc in the corner 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 Ferrocraft 21 electrode makes welding in
this position particularly easy. Use a 3.2mm
electrode at 100 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
3.2mm Ferrocraft 12XP electrode at 100
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