Pilot Arc Discussion; Procedure Recommendations - Lincoln Electric TOMAHAWK 375 AIR Service Manual

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• Replace the nozzle when the orifice exit is eroded
away or oval shaped.
• After the problem is found, or if there is nothing
apparently wrong, reset the machine by turning the
power switch OFF and then ON again. (It is possi-
ble for electrical noise to trip the safety circuit on
rare occasions. This should not be a regular occur-
rence.)
• If the machine does not reset or continues to trip,
consult the Troubleshooting Section.
• Use the proper cutting procedures referred to in

Procedure Recommendations.

PILOT ARC DISCUSSION

The TOMAHAWK 375 AIR has a smooth, continuous
®
pilot arc. The pilot arc is only a means of transferring
the arc to the workpiece for cutting. Repeated pilot arc
starts, in rapid succession, is not recommended as
these starts will generally reduce consumable life.
Occasionally, the pilot arc may sputter or start intermit-
tently. This is aggravated when the consumables are
worn or the air pressure is too high. Always keep in
mind that the pilot arc is designed to transfer the arc to
the workpiece and not for numerous starts without cut-
ting.
The TOMAHAWK 375 AIR does not utilize high fre-
®
quency starting. When the pilot arc is started, a slight
impulse will be felt in the torch handle. This occurrence
is normal and is the mechanism which starts the plas-
ma arc. This impulse can also be used to help trou-
bleshoot a "no start" condition.
OPERATION
PROCEDURE RECOMMENDATIONS
When properly used, plasma arc cutting is a very eco-
nomical process. Improper use will result in a very high
operating cost.
General - In All Cases
• Follow safety precautions as printed throughout this
operating manual and on the machine.
• If piercing is required, slowly lower the torch at an
angle of about 30° to blow the dross away from the
torch tip and slowly rotate the torch to a vertical
position as the arc becomes deeper. This process
will blow a lot of molten metal and dross. Be care-
ful! Blow the dross away from the torch, the opera-
tor and any flammable objects.
• The nozzle should not be dragged on the metal sur-
face. A drag spacer is provided to maintain a con-
sistant touch height. Refer to Touch Parts
Configurations in this Section.
• Where possible, start the cut from the edge of the
work piece.
• Keep moving! A steady speed is necessary. Do not
pause.
TOMAHAWK ® 375 AIR
Torch Standoff
1/16" Standoff
DRAG thru 1/16"
Standoff
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