Lincoln Electric SVM146-A Preheat Temperature for, Plasma Cutting, User Responsibility

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B-7			B-7
		OPERATION
			PREHEAT TEMPERATURE FOR
	WARNING
			PLASMA CUTTING

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ELECTRIC SHOCK can kill.

•Turn off machine at the discon- nect switch on the front of the machine before tightening, cleaning or replacing consum- ables.

-Check the conditions of the inside of the nozzle. If debris has collected, rub the electrode on the inside bottom of the nozzle to remove any oxide layer that may have built up. Refer to

“Suggestions for Extra Utility from the Pro-Cut System.”

Preheat temperature control is not necessary in most applications when plasma arc cutting or gouging. Preheat temperature control may be necessary on high carbon alloy steels and heat treated aluminum for crack resistance and hardness control. Job condi- tions, prevailing codes, alloy level, and other consider- ations may also require preheat temperature control. The recommended minimum preheat temperature for plate thickness up to 1/2 in. (12.7mm) is 70°F (21.1°C). Higher temperatures may be used as required by the job conditions and/or prevailing codes. If cracking or excessive hardness occurs on the cut face, higher pre- heat temperature may be required.

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-Check the condition of the electrode. If the end has a crater-like appearance, replace it along with the nozzle. The maximum wear depth of the electrode is approximately .062 in. (1.6mm). A green and erratic arc will indicate definite electrode failure. The electrode should be replaced immediately.

•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 pressing the "Reset" button. (It is possible 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.

•Use the proper cutting or gouging procedures referred to in “Procedure Recommendations” below.

USER RESPONSIBILITY

Because design, fabrication, erection, and cutting vari- ables affect results, the serviceability of a product or structure is the responsibility of the user. Variation such as plate chemistry, plate surface condition (oil, scale), plate thickness, preheat, quench, gas type, gas flow rate and equipment may produce results different from those expected. Some adjustments to proce- dures may be necessary to compensate for unique individual conditions. Test all procedures duplicating actual field conditions.

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.

GENERAL - IN ALL CASES

•Follow safety precautions as printed throughout this manual and on the machine.

THIN GAUGE SHEET METAL

Torch Standoff Machine Output Setting

45

DRAG thru 1/16"	Output Setting
Standoff	Min. thru Mid. Range

Output set below 45 Amps.

•The nozzle may be dragged on the metal surface, touching it lightly to the surface after piercing a hole. Current control should be set below the mid-range.

•Do not allow cable or body to contact hot surface.

PRO-CUT 80