Inteco HARRIER 280, Instruction Manual, Page: 31 / 228

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Cause Insufficient gas protection.
Solution Use gases suitable to the materials to be welded.
Porosity
Cause Grease, varnish, rust or dirt on the workpieces to
be welded.
Solution Clean the workpieces accurately before welding.
Cause Grease, varnish, rust or dirt on the filler material.
Solution Always use quality materials and products.
Keep the filler material always in perfect condi-
tions.
Cause Humidity in the filler material.
Solution Always use quality materials and products.
Keep the filler material always in perfect condi-
tions.
Cause Incorrect arc length.
Solution Increase the distance between the electrode and
the piece.
Increase the welding voltage.
Cause Humidity in the welding gas.
Solution Always use quality materials and products.
Ensure the gas supply system is always in perfect
conditions.
Cause Insufficient gas protection.
Solution Adjust the gas flow.
Check that the diffuser and the gas nozzle of the
torch are in good conditions.
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 accurately before welding.
Cause Grease, varnish, rust or dirt on the filler material.
Solution Always use quality materials and products.
Keep the filler material always in perfect condi-
tions.
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 weld material.
Solution Always use quality materials and products.
Keep the weld material always in perfect conditions.
Cause Particular geometry of the joint to be welded.
Solution Pre-heat the pieces to be welded.
Carry out post-heating.
Carry out the correct sequence of operations for
the type of joint to be welded.
For any doubts and/or problems do not hesitate to contact
your nearest customer service centre.
6 CONTINUOUS WIRE WELDING THEORY
6.1 Introduction
A MIG system consists of a direct current power source, wire
feeder, wire spool, torch and gas.
MIG manual welding system
The current is transferred to the arc through the fusible elec-
trode (wire connected to positive pole); in this procedure the
melted metal is transferred onto the workpiece through the arc
stream. The automatic feeding of the continuous filler material
electrode (wire) is necessary to refill the wire that has melted
during welding.