MetFab - Air Products Welder's Handbook - Flipbook - Page 11
Spray transfer
Globular transfer
Dip transfer
Voltage (V)
1.0mm SG2 wire
Ferromaxx® 7
26
Operation
22
16
An electric motor feeds the wire into
the arc, and the power source keeps the
arc length at a preset value. This allows
the welder to concentrate on ensuring a
complete fusion of the joint.
Most power sources for MIG/MAG
welding processes are known as
constant voltage machines.
50
180 230
Current (A)
To set up a MIG/MAG welding machine,
there are three key parameters;
• arc current / wire feed speed
• arc voltage
• welding speed
Drive rolls keep
constant wire
feed speed
Spool
of wire
Work
Power supply
unit keeps arc
length constant
The correct settings of these parameters
depend on the type of parent material,
thickness, type of joint, welding position,
type of filler material and weld process gas.
Guide values can be found in data tables
supplied with your welding machine or by
consumables manufacturers.
Air Products provides preliminary weld
procedure specifications (pWPS) and
associated weld procedure qualification records
(WPQR) which contain all key parameters for
commonly welded joints. These can be accessed
via the Air Products website.
The combination of these key parameters
determines the stability of the arc, the size
of the weld and the applied heat input. Heat
input may need to be controlled in order
to achieve required mechanical properties.
Check your WPS for guidance and if you
do not have an approved WPS, seek expert
advise from a qualified welding engineer.
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