Tweco 175 SE Arc Master - Manuel (Page 33)

OpERATION ARC MASTER 175 SE
Manual 0-5054 4-7 OPERATION
this. The electrode needs to be moved along fast
enough to prevent the slag pool from getting ahead
of the arc. To complete the joint in thin plate, turn the
job over, clean the slag out of the back and deposit
a similar weld.
Art # A-07697_AB
Tack Weld
20°-30°
Electrode Tack Weld
Figure 4-12: Butt weld
Art # A-07698
Figure 4-13: Weld build up sequence
Heavy plate will require several runs to complete the
joint. After completing the first run, chip the slag out
and clean the weld with a wire brush. It is important
to do this to prevent slag being trapped by the second
run. Subsequent runs are then deposited using either
a weave technique or single beads laid down in the
sequence shown in Figure 4-13. The width of weave
should not be more than three times the core wire
diameter of the electrode. When the joint is completely
filled, the back is either machined, ground or gouged
out to remove slag which may be trapped in the root,
and to prepare a suitable joint for depositing the
backing run. If a backing bar is used, it is not usually
necessary to remove this, since it serves a similar
purpose to the backing run in securing proper fusion
at the root of the weld.
B. Fillet Welds
These are welds of approximately triangular cross-
section made by depositing metal in the corner of two
faces meeting at right angles. Refer to Figure 4-5.
A piece of angle iron is a suitable specimen with
which to begin, or two lengths of strip steel may be
tacked together at right angles. Using a 1/8" (3.2mm)
E7014 electrode at 120 amps, position angle iron
with one leg horizontal and the other vertical. This
is known as a horizontal-vertical (HV) fillet. Strike
the arc and immediately bring the electrode to a
position perpendicular to the line of the fillet and
about 45° from the vertical. Some electrodes require
to be sloped about 20° away from the perpendicular
position to prevent slag from running ahead of the
weld. Refer to Figure 4-14. Do not attempt to build
up much larger than 1/4" (6.4mm) width with a 1/8"
(3.2mm) electrode, otherwise the weld metal tends
to sag towards the base, and undercut forms on the
vertical edge. Multi-runs can be made as shown in
Figure 4-15. Weaving in HV fillet welds is undesirable.
Art # A-07699_AB
45° from
vertical
60° - 70° from line
of weld
Figure 4-14: Electrode position for HV fillet weld
Art # A-07700_AB
1 2
3
4
5
6
Figure 4-15: Multi-runs in HV fillet weld
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 1/8" (3.2mm) E7014 electrode and
set the current at 120 amps. Make yourself
comfortable on a seat in front of the job and
strike the arc in the corner