voestalpine Bohler Welding URANOS 2000 SMC Mode D'emploi page 38

OPERATING INSTRUCTIONS
» Humidity in the filler metal.
EN
» Incorrect arc length.
» Humidity in the welding gas.
» Insufficient shielding gas.
» The weld pool solidifies too quickly.
Hot cracks
Cause
» Incorrect welding parameters.
» Grease, varnish, rust or dirt on the workpieces to be
welded.
» Grease, varnish, rust or dirt on the filler material.
» Incorrect welding mode.
» Pieces to be welded have different characteristics.
Cold cracks
Cause
» Humidity in the filler metal.
» Particular geometry of the joint to be welded.
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9. OPERATING INSTRUCTIONS
9.1 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 thickness 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.
» Always use quality materials and products.
» Keep the filler metal always in perfect condition.
» Decrease the distance between the electrode and the piece.
» Decrease the welding voltage.
» Always use quality materials and products.
» Ensure the gas supply system is always in perfect condition.
» Adjust the air flow.
» Check that the diffuser and the gas nozzle of the torch are in good
condition.
» Decrease the travel speed while welding.
» Pre-heat the workpieces to be welded.
» Increase the welding current.
Solution
» Decrease the welding current.
» Use a smaller diameter electrode.
» Clean the pieces accurately before welding.
» Always use quality materials and products.
» Keep the filler metal always in perfect condition.
» Carry out the correct sequence of operations for the type of joint to
be welded.
»
Solution
» Always use quality materials and products.
» Keep the filler metal always in perfect condition.
» Pre-heat the workpieces to be welded.
» Carry out post-heating.
» Carry out the correct sequence of operations for the type of joint to
be welded.
Property
Easy to use
High melting speed
High quality of joint
38
Use
All positions
Flat
All positions