Magmate 180P - Fundamentals of MIG, FCAW and MCAW; Welding Technique

12
Process Dip Transfer Globular Transfer Spray Transfer Pulsed Transfer
Metal Inert Gas
(MIG)
● ● ●
Flux Cored
(Gas Shielded)
● ●
*
Flux Cored
(Self Shielded)
● ●
Metal Cored
● ● ●
* Not True Spray
2.4 Fundamentals of MIG, FCAW
and MCAW
Welding Technique
Successful welding depends on the following
factors:
Selection of correct consumables1
Selection of the correct power source2
Selection of the correct polarity on the 3
power source
Selection of the correct shielding gas4
Selection of the correct application 5
techniques
a Correct angle of electrode to work
b Correct electrical stickout
c Correct travel speed
Selection of the welding preparation6
Selection of Correct Consumable
Chemical composition
As a general rule the selection of a wire is
straightforward, in that it is only a matter of
selecting an electrode of similar composition
to the parent material. It will be found,
however, that there are certain applications
that electrodes will be selected on the basis of
its mechanical properties or level of residual
hydrogen in the weldmetal. Solid MIG wires are
all considered to be of the 'low Hydrogen type'
consumables.
The following table gives a general overview of
the selection of some of the BOC range of MIG
wires for the most common materials.
Common Materials Welded with BOC MIG Wire
Material BOC MIG Wire
AS2074 C1,C2,C3,
C4-1,C4-2,C5,C6
BOC Mild Steel MIG Wire
BS3100 AW1,A2,A3 BOC Mild Steel MIG Wire
BS1504-430,480,540 BOC Mild Steel MIG Wire
ASTM
A36,A106,EN8,8A
BOC Mild Steel MIG Wire
Stainless Steel
Grade 304 BOC Stainless Steel 308LSi
Grade 309 BOC Stainless Steel 309LSi
Grade 316 BOC Stainless Steel 316LSi
Physical condition
Surface condition
The welding wire must be free from any surface
contamination including mechanical damage
such as scratch marks.
A simple test for checking the surface condition
is to run the wire through a cloth that has been
dampened with acetone for 20 secs. If a black
residue is found on the cloth the surface of the
wire is not properly cleaned.
Cast and Helix
The cast and helix of the wire has a major
influence on the feedability of MIG wire.
Cast
Helix
Cast – Diameter of the circle
Helix – Vertical height