WIA CP144-1, Руководство оператора

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Weldmatic 350 & 500 | Operator Manual | Model No CP144-2/CP145-2
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7 BASIC WELDING INFORMATION
MIG Welding (GMAW)
Choice of Shielding Gas
The choice of shielding gas is largely
determined by the consumable wire to
be used. Many proprietary shielding gas
mixtures are available.
Some recommended shielding gases are:
– Mild Steel:
Argon + 18% Oxygen;
Argon + 2%
5% Carbon dioxide;
– Aluminium: Argon;
– Stainless Steel: Argon + 1 to 2% Oxygen.
Argon + Helium
Consult your gas supplier if more specific
information is required.
Shielding Gas Flow Rate
In GMAW, one function of the shielding gas
is to protect the moulten weld pool from
the effects of oxygen in the atmosphere.
Without this protection the weld deposit
becomes ‘honeycombed’ in appearance, an
effect which is described as weld porosity.
In draft-free conditions the gas flow rate
required to give adequate protection is
typically 10-12 litres/min. In situations
where drafts cannot be avoided, it may be
necessary to increase this rate up to 20
litres/min, and/or to provide screening of
the work area.
Weld porosity can also be caused by
air entering the gas stream through a
damaged hose, loose gas connection, or
from restriction in the nozzle, such as from
excess build-up of spatter.
When welding aluminium, particular care
must be taken with all aspects of shielding
gas delivery and work piece preparation in
order to avoid weld porosity.
6 NORMAL WELDING
SEQUENCE
Weld Start
Closing the welding gun switch initiates
this sequence of events:
– The gas valve is energised and gas
flow commences;
– Welding voltage is applied between
the work piece and the consumable
wire.
– The wire drive motor is energised.
– The wire touches the work piece, and
the arc is established.
Weld End
Releasing the gun switch initiates this
sequence of events:
– The wire drive motor is de-energised,
and is dynamically braked to a stop;
– The welding current stops.
– The gas valve is de-energised and the
flow of shielding gas ceases.
The quality of the consumable wire
greatly affects how reliably a gas
metal arc welder will operate. For
best results when welding mild
steel, we recommend quality WIA
AUSTMIG ES6. Dirty, rusty or kinked
wire will not feed smoothly through
the gun cable and will cause erratic
welding. Deposits from the wire will
clog the gun cable liner requiring it
to be replaced prematurely.