Page 132 - Welding of Aluminium and its Alloys

MIG welding 117

Gas
nozzle
Consumable Contact
electrode tube
Gas
shield Weld
Parent Weld Arc metal
metal pool

7.1 Fundamental features of the MIG process. Courtesy of TWI Ltd.

7.2 Illustrating the general arrangement of the power source, wire
feeder gas cylinder and work area. Courtesy of TWI Ltd.

of-fusion defects.At higher currents the filler metal is melted from the wire
tip and transferred across the arc as a spray of molten droplets, spray trans-
fer.This condition gives far lower spatter levels and deeper penetration into
the parent metal than dip transfer. When MIG welding aluminium the low
melting point of the aluminium results in spray transfer down to relatively
low welding currents, giving a spatter-free joint.
The low-current, low-heat input dip transfer process is useful for the
welding of thin plate or when welding in positions other than the flat (PA)