Tweco 1000 Merlin(Dec2004) - Manual (Page 49)

Manual 0-2708 5-3 SERVICE
2. Main Arc Extinguishes
a. Cutting speed too slow
b. Torch standoff too high from workpiece
c. Cutting current too high
d. Work cable disconnected
e. Worn torch parts
f. Non-Genuine Thermal Dynamics Parts
3. Excessive Dross Formation
a. Cutting speed too slow
b. Torch standoff too high from workpiece
c. Worn torch parts
d. Improper cutting current
e. Improper gas selection or settings
f. Non-Genuine Thermal Dynamics Parts
4. Short Torch Parts Life
a. Oil or moisture in gas source
b. Exceeding system capability (material too thick)
c. Excessive pilot arc time
d. Starting or finishing off the workpiece
e. Gas flow too low (incorrect pressure or flow setting)
f. Improperly assembled torch
g. Output current too high for parts being used
h. Torch tip contacting workpiece
i. Improper gas selection for parts being used
j. Damaged or loose torch head components
k. Restricted coolant flow
l. Non-Genuine Thermal Dynamics Parts
5. Poor Pilot Starting
a. Non-Genuine Thermal Dynamics Parts
b. High coolant conductivity
5.04 Common Operating Problems
WARNINGS
Disconnect primary power at the source before dis-
assembling the power supply, torch, or torch leads.
Frequently review the Important Safety Precau-
tions in Section 1. Be sure the operator is equipped
with proper gloves, clothing, eye and ear protec-
tion. Make sure no part of the operator’s body comes
into contact with the workpiece while the torch is
activated.
Sparks from the cutting process can cause damage
to coated, painted, and other surfaces such as glass,
plastic and metal.
Handle torch leads with care and protect them from
damage.
A. Piloting
Piloting is harder on parts life than actual cutting because
the pilot arc is directed from the electrode to the tip rather
than to a workpiece. Whenever possible, avoid excessive
pilot arc time to improve parts life.
B. Torch Standoff
Improper standoff (the distance between the torch tip and
workpiece) can adversely affect tip life as well as shield
cup life. Standoff may also significantly affect the bevel
angle. Reducing standoff will generally result in a more
square cut.
C. Edge Starting
For edge starts, hold the torch perpendicular to the work-
piece with the front of the tip at the edge of the work-
piece at the point where the cut is to start. When starting
at the edge of the plate, do not pause at the edge and
force the arc to "reach" for the edge of the metal. Estab-
lish the cutting arc as quickly as possible.
D. Direction of Cut
In the torches, the plasma gas stream swirls as it leaves
the torch to maintain a smooth column of gas. This swirl
effect results in one side of a cut being more square than
the other. Viewed along the direction of travel, the right
side of the cut is more square than the left (Refer to Fig-
ure 5-4). To make a square-edged cut along an inside
diameter of a circle, the torch should move counterclock-
wise around the circle. To keep the square edge along an out-
side diameter cut, the torch should travel in a clockwise direc-
tion.