Tweco 251 Thermal Arc Fabricator - Manual (Page 60)

FABRICATOR 251
SERVICE 5-4 Manual No. 0-4847
WARNING
Disengage the drive roll when testing for gas flow by ear.
2. Inconsistent wire feed
FAULT CAUSE REMEDY
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.
b. Use ‘V’ groove drive feed roller matched to the steel wire size
you are welding.
C. 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
swarf.
a. Swarf is produced by the wire passing through the feed roller,
if excessive pressure is applied to the pressure roller adjuster.
Swarf can also be produced by the wire passing through an
incorrect feed roller groove shape or size. Swarf 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
the contact tip. When using soft electrode wire such as
aluminum it 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
Inconsistent
Wire Feeding
Figure 5-2: Trouble Shooting for Inconsistent Wire Feed