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VIPER MIG 165
OPERATING MANUAL
16.1 Electrode Selection
As a general rule, the selection of an electrode is straight forward, in that it is only a matter of selecting an electrode of
similar composition to the parent metal. However, for some
metals, there is a choice of several electrodes, each of which
has particular properties to suit specific classes of work.
The size of the electrode generally depends on the
thickness of the section being welded, and the thicker the
section, the larger the electrode required. The table gives
the maximum size of electrodes that may be used for various
thicknesses of section based on using a general-purpose
type 6013 electrode.
Correct current selection for a particular job is an important
factor in arc welding. With the current set too low, it is
difficult to strike and maintain a stable arc. The penetration
is reduced and beads with a distinct rounded profile will be
deposited. Too high a current is accompanied by overheating of the electrode, resulting in undercut, burning through of
the base metal and producing excessive spatter.
16.2 Arc Length
To strike the arc, the electrode should be gently scraped on the work until the arc is established. There is a simple rule
for the proper arc length; it should be the shortest arc that gives a good surface to the weld. An arc too long reduces
penetration, produces spatter and gives a rough surface finish to the weld. An excessively short arc will cause sticking of
the electrode and result in poor quality welds. The general rule of thumb for down hand welding is to have an arc length
no greater than the diameter of the core wire.
16.3 Electrode Angle
The angle that the electrode makes with the work is important to ensure a smooth, even transfer of metal. When welding
in down hand, fillet, horizontal or overhead, the angle of the electrode is generally between 5 and 15 degrees towards
the direction of travel. When vertical up welding, the angle of the electrode should be between 80 and 90 degrees to the
workpiece.
16.4 Travel Speed
The electrode should be moved along in the direction of the joint being welded at a speed that will give the size of run
required. At the same time, the electrode is fed downwards to keep the correct arc length at all times. Excessive travel
speeds lead to poor fusion, lack of penetration, etc., while too slow a rate of travel will frequently lead to arc instability, slag
inclusions and poor mechanical properties.
16.5 Material and Joint Preparation
The material to be welded should be clean and free of any moisture, paint, oil, grease, mill scale, rust or any other material
that will hinder the arc and contaminate the weld material. Joint preparation will depend on the method used include
sawing, punching, shearing, machining, flame cutting and others. In all cases, edges should be clean and free of any
contaminates. The chosen application will determine the type of joint.
Electrode Size (ø mm)
Current Range (Amps)
2.5mm
60 - 100
3.2mm
100 - 130
4.0mm
130 - 165
5.0mm
165 - 260
Average Thickness of Material
Maximum Recommended
Electrode Diameter
1.0 - 2.0mm
2.5mm
2.0 - 5.0mm
3.2mm
5.0 - 8.0mm
4.0mm
8.0 - > mm
5.0mm
MMA: Welding Guide
