Welding Current (Amperage)
Correct current selection for a particular job is
an important factor in arc welding.With the
current set too low, difficulty is experienced in
striking and maintaining astable arc. The
electrode tends to stick to the work, penetration
is poor and beads with a distinct rounded
profile will be deposited.Too high current is
accompanied by overheating of the electrode
resulting undercut and burning through of the base metal and producing excessive spatter. Normal
current for a particular job may be considered as the maximum, which can be used without burning
through the work, over-heating the electrode or producing a rough spattered surface.The table shows
current ranges generally recommended for a general purpose type 6013 electrode.
Arc Length
To strike the arc, the electrode should be gently scraped on the work until the arc is established.
Ther is a simple ru
le 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 elect
rode and result in poor quality
welds. General rule of thumb for down hand welding is to have an arc length no greater than the
diameter of the core wire.
Electrode Size
ø mm
Current Range
(Amps)
2.5 mm
60-95
3.2 mm
100-130
4.0 mm
130-165
5.0 mm
165-260
Electrode Angle
The angle that the electrode makes with the work is important to ensure a smooth, eve n transfer of
metal. When welding in down hand, fillet, horizontal or overhead the angle of the electrode is
generally between 5and 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 work piece.
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 al
l 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.
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 casesedges should be clean and free of any contaminates. The type of joint
will be determined by the chosen
application.