Welding Theory; Manual Metal Arc Welding (Mma) - voestalpine bohler welding WF NX 4000 Classic Manual De Instrucciones

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
Type of coating
Acid
Basic
Choosing the welding current
Striking and maintaining the arc
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
93
WELDING THEORY
Use
EN