voestalpine bohler WF NX 3000 Classic Bedienungsanleitung Seite 96

WELDING THEORY
Oxidations
Cause
» Insufficient shielding gas.
Porosity
EN
Cause
» Grease, varnish, rust or dirt on the workpieces to be
welded.
» Grease, varnish, rust or dirt on the filler material.
» Humidity in the filler metal.
» 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.
10. WELDING THEORY
10.1 Manual Metal Arc welding (MMA)
Preparing the edges
Choosing the electrode
Solution
» Adjust the air flow.
» Check that the diffuser and the gas nozzle of the torch are in good
condition.
Solution
» Clean the pieces accurately before welding.
» Always use quality materials and products.
» Keep the filler metal always in perfect condition.
» 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.
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