TigSure Welding Wire Factory |
mig welding wire
Mig welding wire can be aluminum welding wire, stainless
steelwelding wire or other alloy wire specially for mig
weldingprocesses.
Solid wire MIG welding:
Metal inert gas (MIG) welding wasfirst patented in the USA in 1949
for welding aluminium. The arc and weld poolformed using a bare
wire electrode was protected by helium gas, readilyavailable at
that time. From about 1952 the process became popular in the UK
forwelding aluminium using argon as the shielding gas, and for
carbon steels usingCO 2 . CO 2 and argon-CO 2 mixtures are known as
metal active gas (MAG)processes. MIG is an attractive alternative
to MMA, offering high depositionrates and high productivity.
Process characteristics
MIG is similar to MMA in that heat for welding is produced byforming an arc between a metal electrode and the workpiece; the electrode meltsto form the weld bead. The main differences are that the metal electrode is asmall diameter wire fed from a spool and an externally supplied shielding gas isnecessary. As the wire is continuously fed, the process is often referred to assemi-automatic welding.
Shielding gas
In addition to general shielding of the arc and the weld pool,the shielding gas performs a number of important functions:
forms the arc plasma
stabilises the arc roots on thematerial surface
ensures smooth transfer of molten droplets from the wire tothe weld
pool
Thus, the shielding gas will have a substantial effect on
thestability of the arc and metal transfer and the behaviour of the
weld pool, inparticular, its penetration. General purpose shielding
gases for MIG welding aremixtures of argon, oxygen and CO 2 , and
special gas mixtures may containhelium. The gases which are
normally used for the various materials are:
steels
CO 2
argon +2 to 5% oxygen
argon +5 to 25% CO2
non-ferrous
argon
argon / helium
Argon based gases, compared withCO 2 , are generally more tolerant
to parameter settings and generate lowerspatter levels with the dip
transfer mode. However, there is a greater risk oflack of fusion
defects because these gases are colder. As CO 2 cannot be used
inthe open arc (pulsed or spray transfer) modes due to high
back-plasma forces,argon based gases containing oxygen or CO 2 are
normally employed.
Applications
MIG is widely used in most industry sectors and accounts formore than 50% of all weld metal deposited. Compared to MMA, MIG has theadvantage in terms of flexibility, deposition rates and suitability formechanisation. However, it should be noted that while MIG is ideal for'squirting' metal, a high degree of manipulative skill is demanded of thewelder.