Parweld XTS 203 MMA, Руководство оператора

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8
7.0 Fault Finding
MMA welding problem
Description Possible cause Remedy
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
Crack occurring in
weld metal soon after
solidification.
(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.
A gap is left by failure
of the weld metal to fill
the root of the weld
(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
the output current when it detects the rise in arc voltage as the
tungsten is lifted from the work piece.
TIG welding guide ranges
Electrode diameter DC current (amps)
0.040” (1.0mm) 30 – 60
1/16” (1.6mm) 60 – 115
3/32” (2.4mm) 100 – 165
Tungsten electrode types
Electrode
type
Welding application
Colour
code
Thoriated
2%
DC welding of mild steel, stainless
steel and copper. Excellent arc
starting, long life, high current carrying
capacity.
RED
Ceriated
2%
DC welding of mild steel, stainless
steel, copper, aluminium, their alloys
longer life, more stable arc, easier
starting, wider current range, narrower
more concentrated arc
GREY
Guide for selecting filler wire diameter
Filler wire
diameter
DC current range
1/16” (1.6 mm) 20 - 90
3/32” (2.4 mm) 65 - 115
1/8” (3.2 mm) 100 - 165
3/16” (4.8 mm) 200-350
The filler wire diameter specified is a guide only, other diameter
wires may be used according to the welding application
.
Shielding gas selection
Alloy Shielding gas
Aluminium & alloys Pure Argon
Carbon steel Pure Argon
Stainless steel Pure Argon
Nickel alloy Pure Argon
Copper Pure Argon
Titanium Pure Argon
Faul
t
FI
n
DI
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