Selco ETG 402 Manuel D'instructions page 27

Slag inclusions
Cause Poor cleanliness.
Solution Clean the pieces accurately before welding.
Cause Electrode diameter too big.
Solution Use a smaller diameter electrode.
Cause Incorrect edge preparation.
Solution Increase the chamfering.
Cause Incorrect welding mode.
Solution Decrease the distance between the electrode and
the piece.
Move regularly during all the welding operations.
Tungsten inclusions
Cause Incorrect welding parameters.
Solution Decrease the welding voltage.
Use a bigger diameter electrode.
Cause Incorrect electrode.
Solution Always use quality materials and products.
Sharpen the electrode carefully.
Cause Incorrect welding mode.
Solution Avoid contact between the electrode and the weld
pool.
Blowholes
Cause Insufficient shielding gas.
Solution Adjust the gas flow.
Check that the diffuser and the gas nozzle of the
torch are in good condition.
Sticking
Cause Incorrect arc length.
Solution Increase the distance between the electrode and
the piece.
Cause Incorrect welding parameters.
Solution Increase the welding current.
Cause Incorrect welding mode.
Solution Angle the torch more.
Cause Pieces to be welded too big.
Solution Increase the welding current.
Cause Incorrect arc regulation.
Solution Increase the equivalent circuit inductive value setting.
Use a higher setting inductive connection.
Undercuts
Cause Incorrect welding parameters.
Solution Decrease the welding voltage.
Use a smaller diameter electrode.
Cause Incorrect arc length.
Solution Increase the distance between the electrode and
the piece.
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.
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.
Cause Humidity in the welding 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.
Pre-heat the workpieces to be welded.
Increase the welding current.
Hot cracks
Cause Incorrect welding parameters.
Solution Decrease the welding voltage.
Use a smaller diameter electrode.
Cause Grease, varnish, rust or dirt on the workpieces to
be welded.
Solution Clean the workpieces carefully before welding.
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.
Cause Incorrect welding mode.
Solution Carry out the correct sequence of operations for
the type of joint to be welded.
Cause Pieces to be welded have different characteristics.
Solution Carry out buttering before welding.
Cold cracks
Cause Humidity in the filler metal.
Solution Always use quality materials and products.
Keep the filler metal always in perfect condition.
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