WELDSKILL 100, 135, 150 MIG
5-2
Service
5.05 Welding Problems
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, Porosity
and Inconsistent wire feed
Solving Problems Beyond the Welding Terminals - 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 solidifi-
cation 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
1 Gas cylinder contents
and flow meter.
Ensure that the gas cylinder is not empty and the
flow meter is correctly adjusted to 15 litres per
minute.
2 Gas leaks. 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.
Ensure the hose from the solenoid valve to the torch
adaptor has not fractured and that it is connected to
the torch adaptor.
4 Welding in a windy
environment.
Shield the weld area from the wind or increase the
gas flow.
5 Welding dirty, oily,
painted, oxidised or
greasy plate.
Clean contaminates off the work piece.
6 Distance between the
MIG torch nozzle and
the work piece.
Keep the distance between the MIG torch nozzle and
the work piece to a minimum. Refer to section 2.03
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.
B Do not restrict gas flow by allowing spatter to build
up inside the torch nozzle.
C Check that the MIG torch O-rings are not damaged.
Table 5-1
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