Its Repair is challenging and its use is spreading.
Aluminum is making new demands on skills and equipment at every shop. By Bob Jansen, Contributing EditorSelecting A GMA (MIG)
Wire Feeder System
A push feeder is similar to what is used for most steel GMA (MIG) welding.
A variable speed motor pushes wire through the liner to the gun. With push
feeders, the liner length must usually be limited to about 3 meters (10
ft.). Aluminum electrode wire tends to buckle and bind at the drive rolls
when using long liners with a push feeder. This can cause birdnesting. A
push feeder may not work well for feeding the small diameter electrode
wires required for some exterior body panels, especially a soft electrode
like 4043. An advantage of a push feeder is the small size of the gun for
access to most areas.A push-pull feeder has two
motors and two sets of drive rolls. One set of each is in the power source
cabinet and the welding gun. This provides uniform feeding for small
diameter electrode wire. Soft electrode wire, such as 4043, can also be
used with no problems. A push-pull feeder can have a liner more than 9 m
(30 ft.) long. A possible disadvantage is the complexity of this type of
feeder system, sometimes requiring a separate feed cabinet.A spool gun feeding system
is common on GMA (MIG) welding machines set up for aluminum. A spool gun
has a small spool of electrode wire, usually 100 mm (4 in.) in diameter,
attached directly to the welding gun. The spool weighs about .45 kg (1
lb). There is a motor and drive roll set and a short gun liner also
contained on the gun. The short gun liner allows the feeding of 4043
electrode and the use of knurled drive rolls without a problem. There is
virtually no limit to the length of cable from the gun to the power
source, since the electrode wire is not being fed through it. Another
advantage of a spool gun is that because the feeder system is contained in
the gun, a GMA (MIG) welding machine can be set up for both steel and
aluminum at the same time. One possible disadvantage is that a spool gun
may have limited access to welding areas due to its size. Also, the small
size of the spool gun means more frequent changes.