Welding Defects; Maintaining The System - Cebora BRAVO Manual De Instrucciones

• Use mills and brushing machines specifically designed for alu-
minum, and never use them for other materials.
NOTE: If only a torch prepared for steel wires is available, it must
be altered as follows:
• Make sure that the cable is no more than 3 meters long.
• Remove the brass liner nut, gas nozzle, contact tip, and then slip
off the liner.
• Insert our liner Art. 139, making sure that it protrudes from both
ends.
• Screw the contact tip back on so that the liner adheres to it.
• In the free end of the liner, insert the liner nipple and O-ring, and
fasten with the nut without over-tightening.
• Insert the brass tube on the liner and insert the entire unit in the
adapter, after first removing the iron sleeve.
• Cut the liner diagonally so that it is as close as possible to the
wire feeder roller.
• Use wire feeder rollers suitable for aluminum wire.
• Adjust the pressure exerted by the arm of the wire feeder group
on the roller, to the lowest possible setting.

6 WELDING DEFECTS

1 DEFECT- Porosity (within or outside the bead)
CAUSES • Electrode defective (rusted surface)
• Missing shielding gas due to:
- low gas flow
- flow gauge defective
- regulator frosted due to no preheating of the
CO2 protection gas
- defective solenoid valve
- contact tip clogged with spatter
- gas outlet holes clogged
- air drafts in welding area.
2 DEFECT - Shrinkage cracks
CAUSES • Wire or workpiece dirty or rusted.
• Bead too small.
• Bead too concave.
• Bead too deeply penetrated.
3 DEFECT - Side cuts
CAUSES • Welding pass done too quickly
• Low current and high arc voltages.
4 DEFECT - Excessive spraying
CAUSES • Voltage too high.
• Insufficient inductance.
• No preheating of the CO2 protection gas
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7 MAINTAINING THE SYSTEM

• Shielding gas nozzle
This nozzle must be periodically cleaned to remove weld
spatter. Replace if distorted or squashed.
• Contact tip.
Only a good contact between this contact tip and the wire
can ensure a stable arc and optimum current output; you
must therefore observe the following precautions:
A) The contact tip hole must be kept free of grime and oxi-
dation (rust).
B) Weld spatter sticks more easily after long welding ses-
sions, blocking the wire flow.
The tip must therefore be cleaned more often, and replaced
if necessary.
C) The contact tip must always be firmly screwed onto the
torch body. The thermal cycles to which the torch is subjec-
ted can cause it to loosen, thus heating the torch body and
tip and causing the wire to advance unevenly.
• Wire liner.
This is an important part that must be checked often, becau-
se the wire may deposit copper dust or tiny shavings. Clean
it periodically along with the gas lines, using dry compressed
air.
The liners are subjected to constant wear and tear, and the-
refore must be replaced after a certain amount of time.
• Gearmotor group.
Periodically clean the set of feeder rollers, to remove any rust
or metal residue left by the coils. You must periodically check
the entire wire feeder group: hasp, wire guide rollers, liner
and contact tip.
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