voestalpine Bohler URANOS 2000 SMC Manuel D'instructions page 52

Cause Incorrect arc length.
Solution Increase the distance between the electrode and
the piece.
Increase the welding voltage.
Cause Incorrect welding mode.
Solution Decrease the side oscillation speed while filling.
Decrease the travel speed while welding.
Cause Insufficient shielding gas.
Solution Use gases suitable for the materials to be welded.
Oxidations
Cause Insufficient gas protection.
Solution Adjust the gas flow.
Check that the diffuser and the gas nozzle of the
torch are in good condition.
Porosity
Cause Grease, varnish, rust or dirt on the workpieces to
be welded/cut.
Solution Clean the workpieces carefully before welding.
Cause Grease, varnish, rust or dirt on the filler material.
Solution Always use quality materials and products.
Keep the filler metal always in perfect condition.
Cause Humidity in the filler metal.
Solution Always use quality materials and products.
Keep the filler metal always in perfect condition.
Cause Incorrect arc length.
Solution Decrease the distance between the electrode and
the piece.
Decrease the welding voltage.
Cause Humidity in the welding/cutting gas.
Solution Always use quality materials and products.
Ensure the gas supply system is always in perfect
condition.
Cause Insufficient shielding gas.
Solution Adjust the gas flow.
Check that the diffuser and the gas nozzle of the
torch are in good condition.
Cause The weld pool solidifies too quickly.
Solution Decrease the travel speed while welding/cutting.
Pre-heat the workpieces to be welded/cut.
Increase the welding/cutting current.
Hot cracks
Cause Incorrect welding/cutting parameters.
Solution Decrease the welding/cutting voltage.
Use a smaller diameter electrode.
Cause Grease, varnish, rust or dirt on the workpieces to
be welded/cut.
Solution Clean the workpieces carefully before welding/cut-
ting.
Cause Grease, varnish, rust or dirt on the filler metal.
Solution Always use quality materials and products.
Keep the filler metal always in perfect condition.
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Cause
Solution
Cause
Solution
Cold cracks
Cause
Solution
Cause
Solution
Excessive dross
Cause
Solution
Cause
Solution
Cause
Solution
The nozzle overheats
Cause
Solution
Cause
Solution
For any doubts and/or problems do not hesitate to contact
your nearest customer service centre.
7 WELDING THEORY
7.1 Manual Metal Arc welding (MMA)
Preparing the edges
To obtain good welding joints it is advisable to work on clean
parts, free from oxidations, rust or other contaminating agents.
Choosing the electrode
The diameter of the electrode to be used depends on the thick-
ness of the material, the position, the type of joint and the type
of preparation of the piece to be welded.
Electrodes of large diameter obviously require very high currents
with consequent high heat supply during the welding.
Type of coating
Rutile
Acid
Basic
Choosing the welding current
The range of welding current related to the type of electrode
used is specified by the manufacturer usually on the electrode
packaging.
Incorrect welding/cutting mode.
Carry out the correct sequence of operations for
the type of joint to be welded/cut.
Pieces to be welded have different characteristics.
Carry out buttering before welding.
Humidity in the filler metal.
Always use quality materials and products.
Keep the filler metal always in perfect condition.
Particular geometry of the joint to be welded/cut.
Pre-heat the pieces to be welded/cut.
Carry out post-heating.
Carry out the correct sequence of operations for
the type of joint to be welded/cut.
Insufficient air pressure.
Adjust the air flow.
Read the paragraph "Installation ".
Incorrect welding/cutting mode.
Increase the travel speed while welding/cutting.
Worn nozzle and/or electrode.
Replace the faulty component.
Insufficient air pressure.
Adjust the air flow.
Read the paragraph "Installation".
Worn nozzle and/or electrode.
Replace the faulty component.
Property
Easy to use
High melting speed
High quality of joint
Use
All positions
Flat
All positions