Tweco 170 HF Weldskill - Manual (Page 25)

WELDSKILL 170 HF INVERTER
4-3 April 23, 2008
4.04 Arc Welding Electrodes
Metal arc welding electrodes consist of a core wire
surrounded by a flux coating. The flux coating is
applied to the core wire by an extrusion process.
The coating on arc welding electrodes serves a
number of purposes:
A. To provide a gaseous shield for the weld metal,
and preserve it from contamination by the
atmosphere whilst in a molten state.
B. To give a steady arc by having ‘arc stabilisers’
present, which provide a bridge for current to flow
across.
C. To remove oxygen from the weld metal with
‘deoxidisers’.
D. To provide a cleansing action on the work piece
and a protective slag cover over the weld metal to
prevent the formation of oxides while the metal is
solidifying. The slag also helps to produce a bead
of the desired contour.
E. To introduce alloys into the weld deposits in special
type electrodes.
4.05 Types of Electrodes
Arc Welding electrodes are classified into a number
of groups depending on their applications. There are
a great number of electrodes used for specialised
industrial purposes which are not of particular interest
for everyday general work. These include some low
hydrogen types for high tensile steel, cellulose types
for welding large diameter pipes, etc.
The range of electrodes dealt with in this publication
will cover the vast majority of applications likely to be
encountered; are all easy to use and all will work on
even the most basic of welding machines.