Tweco 180 Portable MIG - Manual (Page 52)

FABRICATOR 140, 180 MAINTENANCE
Manual 0-4991 5-2 July 20, 2007
7. Maintain the MIG torch in good working order.
a. Ensure that the gas holes are not blocked and
gas is exiting out of the torch nozzle. Refer to
WARNING below.
b. Do not restrict gas flow by allowing spatter to
build up inside the MIG torch nozzle.
!
WARNING
Disengage the drive roll when testing for gas
flow by ear.
2. Inconsistent wire feed
Wire feeding problems can be reduced by checking the
following points:
1. Wire spool brake is too tight.
a. Feed roller driven by motor in the cabinet will
slip.
2. Wire spool brake is too loose.
a. Wire spool can unwind and tangle.
3. Worn or incorrect feed roller size.
a. Use ‘U’ groove drive feed roller matched to the
aluminum wire size you are welding. Use ‘V’
groove drive feed roller matched to the steel
wire size you are welding. Use ‘knurled V’
groove drive feed roller matched to the flux
cored wire size you are welding.
4. Misalignment of inlet/outlet guides.
a. Wire will rub against the misaligned guides and
reduces wire feedability.
5. Liner blocked with slag.
a. Slag is produced by the wire passing through
the feed roller, if excessive pressure is applied
to the pressure roller adjuster. Slag can also
be produced by the wire passing through an
incorrect feed roller groove shape or size. Slag
is fed into the liner where it accumulates, thus
reducing wire feedability.
6. Incorrect or worn contact tip.
a. The contact tip transfers the weld current to
the electrode wire. If the hole in the contact tip
is too large, then arcing may occur inside the
contact tip resulting in the electrode wire
jamming in there. When using soft electrode
wire such as aluminum, the wire may become
jammed in the contact tip due to expansion of
the wire when heated. A contact tip designed
for soft electrode wires should be used.
7. Poor work lead contact to work piece.
a. If the work lead has a poor electrical contact to
the work piece, then the connection point will
heat up and result in a reduction of power at
the arc.
8. Bent liner.
a. This will cause friction between the wire and
the liner thus reducing wire feedability