Lincoln Electric AC-235 Manual page 20

Heating Heavy Parts
Heavy metal can be heated more rapidly by connecting the
work lead to the work so the arc is between the carbons and
the work as well as between the two carbons. To do this,
connect the lead carbon (the carbon which leads the direc-
tion of travel) to the electrode holder. Connect both the trail
carbon and the work cable to the work or to the welding
table. With this connection, raising the torch reduces the
amount of the arc going to the work thus reducing the heat-
ing. The arc between the carbons and work tends to pit the
surface of the work.
Welding Aluminum Alloys With The
Arc Torch
The need to repair aluminum parts continues to grow.
These repairs can be simply made with an AC welder using
Aluminweld DC coated electrodes as a filler rod and The
Carbon Arc Torch. The arc torch preheats the aluminum
plate, assuring good fusion.
Work Preparation
Here are recommended edge preparations and types of
joints for different thicknesses of base metal. All welds
must be made in the downhand position. Round parts must
be rotated.
Welding Procedures
1. Use the recommended AC currents and carbon sizes list-
ed in the Table on page 19. A headshield is required.
2. Use a l/8" (3.2mm) 'Aluminweld' coated electrode as a
filler rod. Hold it in the left hand (for right-handed people).
3. Hold the arc torch in your right hand and start the arc by
shorting the carbons together and adjusting them to a
1/16" (1.6mm) gap.
4. Hold the arc torch as shown here. Hold your eyes right
over the arc torch looking in between the two carbons.
5. Play the arc 3" to 4" (75 to 100mm) up and down the
joint at the start. This preheat helps to give a smoother
bead and an easier start when the filler rod is applied.
6. Move the torch to the beginning of the joint (right-hand-
ed people should begin at the right and move left).
7. Place the tip of the electrode in the arc. If the coating
melts off and flows easily into the joint, the metal is hot
enough to start welding.
8. Let a droplet of the filler rod melt and fuse into the
joints.
9. Watch the molten puddle. Add more filler metal by mov-
ing the end of the rod in and out of the arc as the right
hand moves the arc torch slowly along the joint.
Practice
When you first try to weld with these procedures, you may
have a tendency to burn through. Therefore, a few minutes
practice before working on the parts to be welded is rec-
ommended. Use scrap material about as thick as the part
you are going to weld. Practice the technique to get the feel
of the arc.
Brazing
The techniques for brazing with an arc torch are very much
like the ones used for gas brazing. Only enough heat is need-
ed to melt the filler metal and to raise the parts to be brazed
to the melting temperature of the filler metal — usually
slightly over 1,000°F. (538°C). A good brazed joint is
assured when the filler metal flows into the joint and adheres
evenly to the surfaces. Use only enough filler metal to make
a smooth joint. Use standard gas brazing rod and flux .
Heat the end of the brazing rod and dip it into the flux. The
flux will stick to the hot rod. Play the arc back and forth a
short distance along the seam when the right temperature is
reached. Apply flux as needed and melt off brazing rod to
fill the seam. Move along the seam until the job is com-
plete.
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