Elettro CF MIG 248 Instruction Manual page 9

assembly while the wire is coming out.
• Screw the contact tip back on, making sure that the hole
diameter is the same as that of the wire used.
• Assemble the gas nozzle.
4.3 WELDING CARBON STEELS WITHOUT GAS
PROTECTION (only for items 247 and 261).
Make sure that the cables are properly inserted on the
terminal board, so that the poles match correctly (see pict.
3).
To attain well connected and protected welds, always work
from left to right and top to bottom. Remove all waste at the
end of each welding session.
Use flux-cored wire Ø 0,9mm.
4.4 WELDING CARBON
PROTECTION.
Make sure that the cables are properly inserted on the
terminal board, so that the poles match correctly (only for
items 247 and 261, see pict. 4).
In order to weld these materials you must:
• Use a welding gas with a binary composition, usually
ARGON + CO2 with percentages of Argon ranging from
75% up. With this blend, the welding bead will be well
jointed and attractive.
Using pure CO2 as a protection gas will produce narrow
beads, with greater penetration but a considerably increase
in splatters.
• Use a welding wire of the same quality as the steel to be
welded. It is best to always use good quality wires, avoiding
welding with rusted wires that could cause welding defects.
• Avoid welding rusted parts, or those with oil or grease
stains.
4.5 WELDING STAINLESS STEEL
Make sure that the cables are properly inserted on the
terminal board, so that the poles match correctly (only for
items 247 and 261, see pict. 4).
Series 300 stainless steels must be welded using a
protection gas with a high Argon content, containing a
small percentage of
(approximately 2%) to stabilize the arc.
Do not touch the wire with your hands. It is important to
keep the welding area clean at all times, to avoid
contaminating the joint to be welded.
4.6 WELDING ALUMINIUM
Make sure that the cables are properly inserted on the
terminal board, so that the poles match correctly (only for
items 247 and 261, see pict. 4).
In order to weld aluminium you must use:
• Pure Argon as the protection gas.
• A welding wire with a composition suitable for the base
material to be welded.
• Use mills and brushing machines specifically designed for
aluminium, and never use them for other materials.
• 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 graphite liner (optional), 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.
STEELS WITH
O2 or carbon dioxide
- 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 aluminium wire.
- Adjust the pressure exerted by the arm of the wire
feeder group on the roller, to the lowest possible setting.
5 WELDING DEFECTS
1 DEFECT
CAUSES
GAS
2 DEFECT
CAUSES
3 DEFECT
CAUSES
4 DEFECT - Excessive spraying
CAUSES
6 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
CO2
oxidation (rust).
B) Weld spatter sticks more easily after long welding
sessions, 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
subjected 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,
because 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
therefore 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.
9
-Porosity (within or outside the bead)
• 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.
- Shrinkage cracks
• Wire or workpiece dirty or rusted.
• Bead too small.
• Bead too concave.
• Bead too deeply penetrated.
- Side cuts
• Welding pass done too quickly
• Low current and high arc voltages.
• Voltage too high.
• Insufficient inductance.
• No preheating of the CO2 protection gas