Tweco 180 Portable MIG - Manual (Page 51)

MAINTENANCE FABRICATOR 140, 180
July 20, 2007 5-1 Manual 0-4991
SECTION 5:
MAINTENANCE & TROUBLESHOOTING
5.04 Solving Problems Beyond the
Welding Terminals
The general approach to fix Gas Metal Arc Welding
(GMAW) problems is to start at the wire spool then work
through to the MIG torch. There are two main areas where
problems occur with GMAW:
1. Porosity
When there is a gas problem the result is usually porosity
within the weld metal. Porosity always stems from some
contaminant within the molten weld pool which is in the
process of escaping during solidification of the molten
metal.
Contaminants range from no gas around the welding arc
to dirt on the work piece surface. Porosity can be reduced
by checking the following points:
1. Gas cylinder contents and flow meter.
a. Ensure that the gas cylinder is not empty and
the flow meter is correctly adjusted to 20CFM
(15 liters per minute).
2. Gas leaks
a. Check for gas leaks between the regulator/
cylinder connection and in the gas hose to the
Power Source.
3. Internal gas hose in the Power Source.
a. Ensure the hose from the solenoid valve to the
MIG torch adaptor has not fractured and that it
is connected to the MIG torch adaptor.
4. Welding in a windy environment.
a. Shield the weld area from the wind or increase
the gas flow.
5. Welding dirty, oily, painted, oxidized or greasy
plate.
a. Clean contaminates off the plate.
6. Distance between the MIG torch nozzle and the
work piece.
a. Keep the distance between the MIG torch nozzle
and the work piece to a minimum.
5.01 Cleaning of the Unit
Periodically remove the right side panel (after
disconnecting the supply cord from the receptacle) and
blow out the interior with clean, dry, compressed air of
not more than 25 PSI air pressure. Do not strike any
components with the air hose nozzle.
5.02 Cleaning of the Feed Rolls
Clean the wire groove on the feed roll at frequent intervals.
This cleaning operation can be done by using a small wire
brush. To clean the wire groove, loosen the pressure
device and lift the feedroll pressure arm. Remove all wire
from the feedhead. Wipe off the bearing roll (the “top”
roll in the feedhead).
5.03 Basic Troubleshooting
The basic level of troubleshooting is that which can be
performed without special equipment or knowledge, and
without removing the covers from the Power Source.
If major components are faulty, then the Power Source
should be returned to an Accredited THERMAL ARC
Service Agent for repair.