Mig Welding Troubleshooting; Porosity Problems - Weldclass Weldforce 155M Operating Instructions Manual

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11.11 MIG Welding Troubleshooting

The general approach to fix MIG welding problems is to start at the wire spool then work through to the
MIG torch. There are two main areas where problems occur with MIG: Porosity and Inconsistent wire feed.
11.11.1

Porosity Problems

When there is a gas problem the result is usually porosity within the weld metal. Porosity always 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.
Figure 39
Contaminants range from no gas around the welding arc to dirt on the workpiece surface. Porosity can
be reduced by checking the following points.
Fault
Shielding gas cylinder contents
and gas regulator
Gas leaks
Internal gas hose in the Power
Source
Welding in a windy environment
Welding dirty, oily,
oxidized or greasy plate
Distance between the MIG torch
nozzle and the work piece
Maintain the MIG torch in good
working order.
Table 12
WARNING! Disengage the feed roll when testing for gas flow by ear
42
Troubleshooting - Porosity
Cause
Ensure that the shielding gas cylinder is not empty and the gas
regulator is correctly adjusted to at least 15 litres per minute
Check for gas leaks between the regulator/cylinder connection and
in the gas hose to the Power Source.
Ensure the hose from the solenoid valve to the torch adaptor has
not fractured and that it is connected to the torch adaptor. This
should only be done by qualified technician.
Shield the weld area from the wind or increase the gas flow or use
gasless welding wire
painted, Clean contaminates off the work piece.
Keep the distance between the MIG torch nozzle and the work piece
to a minimum.
Ensure that the gas holes are not blocked in the tip holder and gas
is exiting out of the torch nozzle.
Do not restrict gas flow by allowing spatter to build up inside the
torch nozzle.
Check that the MIG torch O-rings are not damaged on the Euro
connector.
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