22
The illustrations in Figure 19 show the
sequence for laying multiple pass beads into
a single V butt joint.
NOTE: WHEN USING SELF-SHIELDING
FLUX-CORE WIRE it is very important to thor-
oughly chip and brush the slag off each com-
pleted weld bead before making another
pass or the next pass will be of poor quality.
Fillet Weld Joints. Most fillet weld joints, on
metals of moderate to heavy thickness, will
require multiple pass welds to produce a
strong joint. The illustrations in Figure 20
show the sequence of laying multiple pass
beads into a T fillet joint and a lap fillet joint.
SPECIAL WELDING METHODS
SPOT WELDING
The purpose of a spot weld is to join pieces
of metal together with a spot of weld instead
of a continuous weld bead. There are three
methods of spot welding: Burn-Through,
Punch and Fill, and Lap (see Figure 21).
Each has advantages and disadvantages
depending on the specific application as
well as personal preference.
1. The BURN-THROUGH METHOD welds
two overlapped pieces of metal together
by burning through the top piece and into
the bottom piece.
With the burn-through method, larger wire
diameters tend to work better than smaller
diameters because they have greater current
carrying capabilities allowing the arc to burn
through very quickly while leaving a minimal
amount of filler metal build up. Wire diame-
ters that tend to work best, with the burn-
through method, are 0.030 inch diameter
solid wire or 0.035 inch self-shielding flux-
corewire.
Do not use 0.023 inch diameter solid or
0.030 inch self-shielding flux-core wires
when using the burn-through method
unless the metal is VERY thin or excessive
filler metal build-up and minimal penetra-
tion is acceptable.
Always select the HIGH heat setting with the
burn-through method and tune in the wire
speed prior to making a spot weld.
2. The PUNCH AND FILL METHOD produces
a weld with the most finished appearance
of the three spot weld methods. In this
method, a hole is punched or drilled into
Figure 19. Butt Joints
Figure 20. Fillet Weld Joints
Figure 21. Spot Welding
