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6.0 Basic Welding Techniques
6.1
Fundamentals of Gasless Flux
Cored Arc Welding
Welding technique
Successful gasless flux cored arc welding depends
on the following factors:
• Selection of correct consumables.
• Selection of the correct power source.
• Selection of the correct application techniques:
Correct angle of electrode to work
–
Correct electrical stick-out
–
Correct travel speed
–
• Selection of the welding preparation.
Selection of correct consumables
Chemical composition
As a general rule, the selection of a wire is straight
forward, in that it is only a matter of selecting
an electrode of similar composition to the parent
material. However, there are certain applications
for which electrodes will be selected on the basis
of mechanical properties or the level of residual
hydrogen in the weld metal.
The classification system for flux cored wires will
provide an indication of the residual hydrogen
level that can be expected in the weld metal.
Physical condition
Surface condition
BOC flux cored wires are supplied as an in-line
baked product and therefore have a typical dark
surface appearance.
The wire must, however, be free from any surface
contamination, including surface rust. Most flux
and metal cored wires have a thin film of graphite
on the surface of the wire to assist with feedability.
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Selection of power source
Power sources for flux cored welding are selected
on a number of different criteria, including:
• Maximum output of the machine.
• Duty cycle.
• Output control (voltage selection, wire feed
speed control).
• Portability.
Correct application techniques
Direction of travel
Flux cored welding is normally performed using
a drag technique. The welding torch is tilted to
a 50-60° backhand angle. If, however, a flatter
bead profile is required the backhand angle can
be reduced.
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