the Step to direct the arc precisely at the intersection
between the bore surface and the previously laid weld deposit, or slightly favoring the
base metal.
Another possible reason for lack of fusion is that the rotation travel speed is too slow for
the wire speed being used. If rotation is too slow, the welding arc will be directed on top
of the currently melted weld puddle. If this puddle is too large and deep, the melting of
the base metal must be done solely due to the heat of the weld puddle. Being only a little
over 3,000°F, this is seldom enough. Instead, the arc itself, with a temperature of about
10,000°F and a very high heat density will ensure that the base metal is melted before
metal is deposited on top of it. In addition, a slow rotational speed can produce a bead
thickness that is too great which will contribute to cold lapping.
L
ACK

OF
F
USION

TO

THE
P
REVIOUS
W
ELD
B
EAD

OF

THE
S
AME
L
AYER
This is usually caused by too much Step. The welding arc is playing too much on the
bore surface and not enough on the previously deposited bead. Direct the arc at the exact
intersection of the previous bead and the bore surface.
It is also possible that the arc voltage is too low. Generally it is unwise to use voltages
below l6 volts, but resist the temptation to use voltages above l8 to 19 volts. A voltage of
17
½
is normal.
L
ACK

OF
F
USION

AT

THE
R
OOT

AND
G
ENERAL
I
NABILITY

TO
C
ONTROL
B
EAD
Arc voltage is too high for the current density. In a bore, when the arc becomes too long
(the arc voltage is too high), the arc tends to fan out forming a cone around the desired
point of heating (the root). This cone can be hollow at its center. The bead then might
split into two distinct beads one on the base metal, one on the previous bead.
Lower the arc voltage to cause the arc to become more concentrated and heat the root.
This is usually most noticeable during any sort of spray transfer pulsed or not. Unless
the currents are very high (over the capacity of the 306-P), there must be at least an occa-
sional crackling sound. Otherwise, the voltage is too high. A constant crackle is more
appropriate. The crackle sound results when the welding wire contacts the weld puddle. TRO UBLESHOOTING
Common Welding Problems and Their Cures
306-P BoreWelder Operators Manual
73
S
EPARATION

OF

THE
B
UILDUP
F
ROM

THE
U
NDERLYING
B
ASE
M
ATERIAL
Separation of the weld from the base material generally falls into two classes:
The weld did not fuse to the base metal. Instead, it merely cold lapped onto it. Refer
to Lack of Fusion to the Bore Surface on page 72 for more information.
The weld fused with the base metal but now it has separated. This is often confused
with the cold lap described above; but, it is usually caused by underbead cracking.
The weld fuses but then, due to excessive hardness, the stresses induced by the weld
cooling combined with the stress riser formed because of a difference in hardness
causes a crack to form underneath the weld. The crack propagates along the fusion
line or HAZ (Heat Affected Zone). The HAZ has usually become too hard to do its
share of yielding to the shrinkage stresses. In addition, the configuration of the work
piece is usually quite rigid, forcing the weld to absorb most of the shrinkage forces.
The sudden change in hardness at this HAZ interface makes it a stress riser. The result
can be an underbead crack.
The cure for an underbead crack usually is to increase the preheat of the work piece.
Another possible cure is to slow down the rotation speed. Either of these lessen the
quench effect of the heat affected metal and thus reduce the hardness of the HAZ. This
also increases the thickness of the HAZ making it less abrupt and reducing the stress riser
effect.
W
IRE
B
URNING
B
ACK

TO

THE
C
ONTACT
T
IP
W
HILE
W
ELDING
Refer to the next topic, Wire Feeding Stops and Wire Burns Back to Tip.
W
IRE
F
EEDING
S
TOPS

AND
W
IRE
B
URNS
B
ACK

TO
T
IP
This is usually caused by a mechanical blockage of the welding wire. It can be caused by
a pile up of debris at the cone entrance to the contact tip. This debris jams between the
wire and contact tip bore. When the wire stops and the welding power supply remains on,
the wire burns back to the contact tip and the contact tip melts as it becomes the new
electrode.
In addition, if the contact tip becomes too hot, the wire may seize to it. If this happens, it
probably means the arc voltage is too high and lowering it should prevent the seizing and
may improve the welding.
Changing the liners is usually not necessary in cases of wire stoppage. Sometimes the
liner right at the torch nozzle becomes too hot and should be replaced. But generally, the
liners will last a long time if blown out occasionally.
Refer to Wire Feed Drive Roll Pressure and Wire Seizing on page 43 in Chapter 2.
W
IRE
B
URNING
B
ACK

TO

THE
C
ONTACT
T
IP
W
HEN
W
ELDING

IS
S
TOPPED
Burnback time of the Control Box is set too long. A time of about 75-140 milliseconds is
normal for both short arc and pulsed spray. Call Bortech for an adjustment procedure. TROUBLESHOOTING
Common Welding Problems and Their Cures
74
306-P BoreWelder Operators Manual
5
W
ELDING
W
IRE
W
ILL
N
OT
F
EED
T
HROUGH

THE
O
FFSET
H
EAD
This could be caused by a kink in the liner within the offset head. If so, it is best to find
the cause of the kink before proceeding. There are usually two possible causes for this
condition.
On older style offset heads, there was no physical stop to limit head travel. Moving the
head radially past the body could have kinked the liner.
If the wire has become jammed (at the contact tip for instance) and it is pushed too
hard, the liner will be unable to support the wire in the hollow and unsupported Offset
Head Space. The liner will collapse making it impossible for further wire feeding.
This usually is only an issue with the Top Mount Push/Pull feed option. This second
feeder can be set to push the wire very hard. It is important to set the drive rolls loose
enough not to cause this condition. A reading of about 1.0 on the Pull feeder is normal.
You should be able to block the wire travel at the contact tip and have the system
survive. In addition, the wire that was in the system should be as it entered it straight. If the liner in the Offset Head has collapsed, check to be sure the liner
diameter is .188 (as opposed to .146). If the liner diameter is .146 and collapsing
has been a problem, consult Bortech for an upgrade.
W
ELD
B
EADS

ARE
R
OPY To make the beads wet out more and become less ropy, an increase in the arc voltage up
to about 18 volts may help. But probably the most wetting will be obtained by increasing
the inductance of the system. Most welding power supplies have an inductance control.
Watch what happens as you rotate the inductance knob. More inductance tends to spread
out the weld puddle.
N
OTE
:
As you rotate the inductance knob, the arc voltage probably needs to be altered some-
what to obtain optimum performance. (Lincoln power supplies have a Pinch control.
This is inductance but it is labeled backward with higher numbers being less inductance.)
If the power supply does not have an inductance control, you can add inductance by
wrapping either welding cable around a steel core. A piece of heavy wall 4 pipe or a 4
solid works well. Try one wrap at a time while welding. Typically, 2 to 20 wraps should
be sufficient.
A sign of too much inductance is difficulty in starting the arc. The wire tends to stub
and has difficulty recovering. Also, if the electrode tends to stub excessively while weld-
ing and the arc volts are not too low, you should suspect too much inductance.
T
OO
M
UCH
S
PATTER
The usual cause for too much spatter can be that the arc voltage is too high. The arc
should have an even sound that is not violent. A setting of 15
½
to 18 volts is normal.
Above 18 volts, the arc will become much more uneven and labored and the transfer will
become globular. Avoid this range.
The shielding gas also has a marked effect on weld spatter. For spatter control, a shield-
ing of argon with less than 15% CO
2
is recommended. (Bortech often uses 92% argon
8% CO
2
.) More CO
2
than this tends to cause excessive spatter. TRO UBLESHOOTING
Common Welding Problems and Their Cures
306-P BoreWelder Operators Manual
75
T
ORCH
N
OZZLE
B
ECOMES
T
OO
H
OT
This is usually the result of using an arc voltage that is too high. If a short arc is used,
keep the voltage between 15
½
and 18 volts. If Pulse spray is used, adjust the parameters
so you can hear at least a slight crackle or use the Bortech-recommended Low Voltage
Pulsing method (see Using a Low Voltage on page 63 in Chapter 4 ).
T
ORCH
M
OVEMENT
(S
PINDLE
R
OTATION
) B
ECOMES
J
ERKY

AT
S
LOW
S
PEEDS
It is possible the bronze rotatable power couplings need to be resurfaced. This condition
is usually the result of excessive currents. Please contact Bortech and arrange to have the
couplings resurfaced.
P
OROSITY

IN

THE
W
ELD
Porosity is caused by impurities gassing in the weld. Although the welding wires used
contain substantial amounts of deoxidizers and cleansers, there is a point at which these
additives cannot keep up with the impurities. Some of the reasons for porosity are:
Problem with shielding gas. This might include a restriction in flow due to spatter
buildup, etc. Or, the gas flow may be too high, causing turbulence. A flow rate of 20 to
40 CFH is recommended. If the weld is not shielded from the atmosphere, the oxygen
and nitrogen will react with the weld metal, causing poro