Lincoln Electric IM491-B manual Pilot Arc Discussion, Procedure Recommendations, General

F. When ready to cut, place the work lead on the piece to be cut, place the torch near the work, make certain all safety precautions have been taken and pull the trigger.

-The air will flow for a preflow time of 2 seconds and the pilot arc will start. (This is true unless the machine is in postflow, then the preflow time is skipped.)

-The “Output ON” LED will light.

-The pilot arc will run for 1.8 seconds and shut off unless the plasma is brought in contact with the work and the arc is transferred.

-When the arc is transferred, cutting begins. When finished cutting, release the trigger.

G. When the trigger is released, the arc will stop.

-The air will continue to run for 60 seconds of postflow. If the trigger is activated within the first 12 seconds, the pilot arc will immediately restart. After twelve seconds, a double trigger pull is required to start the arc. The second trig- ger pull must follow the first within one second to start the pilot arc.

H. If the “Safety” LED lights at any time, check the following:

WARNING

ELECTRIC SHOCK CAN KILL.

•Turn off machine at the disconnect switch at the back of the machine before tightening, cleaning or replacing consum- ables.

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•Check the assembly of the torch consumables. If they are not properly in place then machine will not start.

•Check the conditions of the inside of the nozzle. If debris has collected, scrape it out with a piece of sturdy wire or a suitable drill bit. Refer to“Suggestions for Extra Utility from the PRO- CUT system”.

•After the problem is found, reset the machine by pressing the “Safety Reset” button. (It is possi- ble for electrical noise to trip the safety circuit on rare occasions. This should not be a regular occurrence.)

•If the machine does not reset or continues to trip, consult the Troubleshooting Section of this manual.

Pilot Arc Discussion:

The PRO-CUT 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, are not recommended, as this will reduce consumable life. Occasionally, the pilot arc may sputter or start intermittently. This is aggravated when the consumables are worn or the air pressure is too high. Keep in mind that the pilot arc is designed to transfer the arc to the workpiece and not for numerous starts without cutting.

Procedure Recommendations

When properly used, plasma arc cutting or gouging is a very economical process. Improper use will result in a very high operating cost.

If the nozzle is touched to the work while cutting, the output current will be reduced to minimum until the nozzle is removed from the work.

General

•Follow safety precautions as printed inside the operating manual and on the machine.

•Either the S19972 standoff guide or S19973 and S19974 contact attachments are recom- mended for all cutting applications to protect the torch from dross and improper arcing condi- tions.

•Use proper cutting or gouging procedures referred to in procedures guideline.

Material thickness below .75 (19mm):

Output set below mid-range.

•Do not allow the torch cable or body to contact hot surfaces.

•The best cut quality is obtained by reducing the current to a level that is adequate for the maxi- mum travel speed.

•Aluminum, copper and other nonferrous metals typically require more current than the same thickness of steel.

•For thickness below .75” (19mm) use an S19961-2 nozzle (1.4mm dia. orifice). The S19972 standoff guide should be set in the low- est position for maximum standoff.

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