Tweco 175 SE Arc Master - Manuel (Page 38)

ARC MASTER 175 SE SERVICE
SERVICE 5-2 Manual 0-5054
Description Possible Cause Remedy
1. Gas pockets or voids in weld
metal (Porosity).
A. Electrodes are damp.
B. Welding current is too
high.
C. Surface impurities such as
oil, grease, paint, etc.
A. Dry electrodes before use.
B. Reduce welding current.
C. Clean joint before welding
2. Crack occurring in weld
metal soon after solidification
commences.
A. Rigidity of joint.
B. Insufficient throat thickness.
C. Cooling rate is too high.
A. Redesign to relieve weld joint
of severe stresses or use crack
resistance electrodes.
B. Travel slightly slower to allow
greater build up in throat.
C. Preheat plate and cool slowly.
3. A gap is left by failure of the weld
metal to fill the root of the weld.
Insufficient Gap
Incorrect Sequence
Art # A-05866_AC
A. Welding current is too low.
B. Electrode too large for joint.
C. Insufficient gap.
D. Incorrect sequence. A. Increase welding current
B. Use smaller diameter electrode.
C. Allow wider gap.
D. Use correct build-up sequence.
4. Portions of the weld run do
not fuse to the surface of the
metal or edge of the joint
Art # A-05867_AC Lack of
inter-run fusion
Lack of side fusion,
scale dirt, small electrode,
amperage too low
Lack of root fusion
Lack of fusion caused by dirt,
electrode angle incorrect,
rate of travel too high
A. Small electrodes used on
heavy cold plate.
B. Welding current is too low.
C. Wrong electrode angle.
D. Travel speed of electrode is
too high.
E. Scale or dirt on joint sur-
face.
A. Use larger electrodes and pre-heat
the plate.
B. Increase welding current
C. Adjust angle so the welding arc
is directed more into the base
metal
D. Reduce travel speed of elect-
rode
E. Clean surface before welding.
5. Non-metallic particles are
trapped in the weld metal
(slag inclusion).
Not cleaned,
or incorrect
electrode
Slag
trapped in
undercut
Slag trapped in root
Art # A-05868_AC
A. Non-metallic particles
may be trapped in under-
cut from previous run.
B. Joint preparation too res-
tricted.
C. Irregular deposits allow slag
to be trapped.
D. Lack of penetration with
slag trapped beneath weld
bead.
E. Rust or mill scale is pre-
venting full fusion.
F. Wrong electrode for position
in which welding is done.
A. If bad undercut is present, clean
slag out and cover with a run from
a smaller diameter electrode.
B. Allow for adequate penetration and
room for cleaning out the slag.
C. If very bad, chip or grind out
irregularities.
D. Use smaller electrode with
sufficient current to give adequate
penetration. Use suitable tools to
remove all slag from corners.
E. Clean joint before welding.
F. Use electrodes designed for
position in which welding is done,
otherwise proper control of slag is
difficult.
5.02 STICK Welding Problems