Valley FABRICATOR 251, Service Manual

Page: 58 / 104

6-2 August 22, 2008
FABRICATOR 251 SERVICE MANUAL
6.02 Solving Problems Beyond the Welding Terminals
The general approach to fix GMAW/FCAW problems is to start at the wire spool then work through to the MIG torch.
There are two main areas where problems occur:
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:
FAULT CAUSE REMEDY
1. Gas cylinder
contents and flow meter
a. Ensure that the gas cylinder is not
empty and the flow meter is correctly
adjusted to 25CFM (15 litres per minute)
2. Gas leaks
a. Check for gas leaks between the
reulator/flowmeter connection and in the
gas hose to the power supply
3. Internal gas hose in
the power supply
a. The hose from the solenoid valve to
the MIG torch adaptor may be fractured
or disconnected from the MIG torch
adaptor. Return to an Accredited Valley
National Gases Service Agent for repair.
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.
Porosity
Table 6-1: Porosity Problems
WARNING
Disengage the drive roll when testing for gas flow by ear.