highest settings, an arc length up to 20 mm can be enough when welding
on maximum settings.
5.2. GENERAL WELDING TIPS
From time to time, some faults may be observed in the weld owing to
externa
l influences rather due to welding machine’s faults. Here are
some that you may come across :
·
Porosity
Small holes in the weld, caused by break-down in gas coverage of the
weld or sometimes by foreign bodies inclusion. Remedy is, usually, to
grind out the weld. Remember, check before the gas flux (about 8
liters/minutes), clean well the working place and finally incline the torch
while welding.
·
Spatter
Small balls of molten metal which come out of the arc. A little quantity is
unavoidable, but it should be kept down to a minimum by selecting
correct settings and having a correct gas flow and by keeping the welding
torch clean.
·
Narrow heap welding
Can be caused by moving the torch too fast or by an incorrect gas flow.
·
Very thick or wide welding
Can be caused by moving the torch too slowly.
·
Wire burns back
It can be caused by wire feed slipping, loose or damaged welding tip,
poor wire, nozzle held too close to work or voltage too high.
·
Little penetration
It can be caused by moving torch too fast, too low voltage setting or
incorrect feed setting, reversed polarity, insufficient blunting and distance
between strips. Take care of operational parameters adjustment and
improve the preparation of the workpieces.
·
Workpiece’s piercing
It may be caused by moving the welding torch too slow, too high welding
power or by an invalid wire feeding.
·
Heavy spatter and porosity
It can be caused by nozzle too far from work, dirt on work or by low gas
flow. You have to the two parameters, remeber that gas has not to be
lower than 7-8 liters/ min. and that the current of welding is appropriated
to the wire you are using. It is advisable to have a pressure reducer of
input and output. On the manometer you can read the range expressed
in liter.
·
Welding arc instability
It may be caused by an insufficient welding voltage, irregular wire feed,
insufficient protective welding gas.
DESCRIPTION OF SIGNS AND SYMBOLS
1 ~
Single phase alternating voltage
3 ~
Three phase alternating voltage
U
0
… (V)
Nominal open circuit voltage
Transformer-rectifier
EN 60974-1
Norm of reference
Flat characteristic
MIG-MAG wire feed welding
U
1
… (V/Hz)
Nominal values of mains voltage and frequency
I
2
… (A)
Welding current
I
1 max
(A)
The welding unit's maximum absorbed current
I
1 eff
… (A)
Effective current supplied
X
Duty cycle
IP21
The welding unit's protection class
H
The transformer's insulation class.
Welding machine suitable for use in environments
with heightened risk of electric shock.
Symbols referring to safety regulations
FAULT FINDING
FAULT
Wire isn’t conveyed when
Feed roll is turning
Wire feeding in jerk or erratic
way
No arc
Porous welding seams
The machine suddenly stops
welding operations after an
extended and heavy duty use
REASON
1) Dirt in liner and/or contact tip
2) The frition brake in the hub is too tightened
3) Faulty welding torch
1) Contact tip defect
2) Burns in contact tip
3) Dirt in feed roll groove
4)
Feed roll’s groove worn
1) Bad concat between earth clamp and workpiece
2) Short-circuit between contact tip and gas shroud
1) Failre of gas shield owing to spatters in gas shro
2) Wrong welding torch distance and/or inclination
from workpiece
3) Too small gas flux
4) Humid workpieces
5) Heavily rusted workpieces
1) Welding machine overheated due to an
excessive use in stated duty cycle
REMEDY
Blow with compressed air, replace contact tip
Loosen
Check sheating of torches wire guide
Replace
Replace
Clean
Replace
Tighten earth clamp and check connections
Clean, replace tip and/or shroud as necessary
Clean gas shroud from spatters
The length of stick out wire from tip must be 5
–
10mm. Inclination not less than 60 degrees in relation
to woekpiece
Increase flux of welding gas
Dry with heat producer
Clean workpieces from rust
Don’t switch off the machine, let it cool down for about
20/30 minutes
