A wire ring with an excessive diameter
can cause an irregular electrical
contact between the contact tip and the
wire, thereby causing an unstable arc.
In automatic gas metal arc welding (GMAW) with
robots and exclusive-use automatic systems you may
adjust the wire straightener in order to deliver the
welding wire as straight as possible from the contact tip
and thus facilitate better wire tracking onto the welding
line. This method, however, can have an adverse effect
on the regular electrical contact between the contact tip
and the wire, thereby causing an unstable arc. This is a
typical cause of unstable arc, even though the wire
feeding is smooth.
The tip-to-wire irregular electrical contact can occur
where the contact pressure of the wire onto the contact
tip is insufficient. The wire-to-tip contact pressure is
predominantly affected by the diameter of the wire ring
As the wire ring diameter increases, the wire-to-tip
contact pressure decreases; consequently, more unstable
arcs can occur . Therefore, the
diameter must be controlled small enough􀊵normally
600 mm or smaller􀊵by adjusting the wire straightener
and pressure roller of the wire feeder to maintain stable
wire-to-tip contact pressure. In addition, the use of a loose contact tip having an
excessively large inside diameter over the wire diameter
or being worn out causes more unstable arcs.
An unstable arc caused by tip-to-wire irregular
electrical contact can also cause fusion at the interface
between the contact tip and wire, which can damage the
inside surface of the contact tip and markedly increase
the wire feeding resistance, thereby damaging the wire
surface at the wire feeding roller. Therefore, this
electrical trouble can cause subsequent wire feeding
trouble.
To prevent such multiple troubles, when irregular
electrical contact causes seriously unstable arcs or arc
cutting, you should not only renew the contact tip, but
also remove all the wire extended from the wire pressure
roller to the welding torch through the conduit. Take
preventive measures against the irregular electrical
contact before restarting welding.
Unstable arc can also be caused by
an excessively long or small diameter
welding cable due to a voltage drop.
GMAW power sources are designed so that they
perform best when the welding cable, which has a
specified diameter according to the rated welding
current, is extended 5-10m long in general. Therefore,
the use of a cable that is either longer or thinner can
cause poor arc stability due to a voltage drop. In order to
overcome this trouble, increase the output terminal
voltage or use a thicker􀊵 thus lower electrical
resistance􀊵welding cable to compensate the voltage
drop.
When a long welding cable is spiraled during use, the
arc can become more unstable because of an increase of
inductance of the welding cable. This is why a long
welding cable should be kept straight in use.
know more @ http://www.kobelcowelding.com/Kobelco%20Welding%20Today/Vol-7(No1).pdf
A wire ring with an excessive diameter
can cause an irregular electrical
contact between the contact tip and the
wire, thereby causing an unstable arc.
In automatic gas metal arc welding (GMAW) with
robots and exclusive-use automatic systems you may
adjust the wire straightener in order to deliver the
welding wire as straight as possible from the contact tip
and thus facilitate better wire tracking onto the welding
line. This method, however, can have an adverse effect
on the regular electrical contact between the contact tip
and the wire, thereby causing an unstable arc. This is a
typical cause of unstable arc, even though the wire
feeding is smooth.
The tip-to-wire irregular electrical contact can occur
where the contact pressure of the wire onto the contact
tip is insufficient. The wire-to-tip contact pressure is
predominantly affected by the diameter of the wire ring
As the wire ring diameter increases, the wire-to-tip
contact pressure decreases; consequently, more unstable
arcs can occur . Therefore, the
diameter must be controlled small enough􀊵normally
600 mm or smaller􀊵by adjusting the wire straightener
and pressure roller of the wire feeder to maintain stable
wire-to-tip contact pressure. In addition, the use of a loose contact tip having an
excessively large inside diameter over the wire diameter
or being worn out causes more unstable arcs.
An unstable arc caused by tip-to-wire irregular
electrical contact can also cause fusion at the interface
between the contact tip and wire, which can damage the
inside surface of the contact tip and markedly increase
the wire feeding resistance, thereby damaging the wire
surface at the wire feeding roller. Therefore, this
electrical trouble can cause subsequent wire feeding
trouble.
To prevent such multiple troubles, when irregular
electrical contact causes seriously unstable arcs or arc
cutting, you should not only renew the contact tip, but
also remove all the wire extended from the wire pressure
roller to the welding torch through the conduit. Take
preventive measures against the irregular electrical
contact before restarting welding.
Unstable arc can also be caused by
an excessively long or small diameter
welding cable due to a voltage drop.
GMAW power sources are designed so that they
perform best when the welding cable, which has a
specified diameter according to the rated welding
current, is extended 5-10m long in general. Therefore,
the use of a cable that is either longer or thinner can
cause poor arc stability due to a voltage drop. In order to
overcome this trouble, increase the output terminal
voltage or use a thicker􀊵 thus lower electrical
resistance􀊵welding cable to compensate the voltage
drop.
When a long welding cable is spiraled during use, the
arc can become more unstable because of an increase of
inductance of the welding cable. This is why a long
welding cable should be kept straight in use.
know more @ http://www.kobelcowelding.com/Kobelco%20Welding%20Today/Vol-7(No1).pdf
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