Tweco 190 MIG Thermal Arc Fabricator - Manual (Page 51)

FABRICATOR 190 WELDING MACHINE
Manual No. 0-4838 5-3 MANUAL GMAW WELDING
5.02 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 Supply.
If major components are faulty, then the Power Supply
should be returned to an Accredited Thermal Arc Service
Agent for repair.
5.03 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 20-
25CFM (15 litres 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.
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.
c. Check that the MIG gun O-rings are not
damaged.
!
WARNING
Disengage the drive roll when testing for gas
flow by ear.