Page 25 - MetalForming July 2017

Correct Shield cap with spatter
Pierce Point
Lead-In
Overburn
Correct
Pierce Point
Lead-In Lead-Out
Incorrect—do not include a circular lead-out on holes
Fig. 5
piece can cause a misfire, diminishing electrode life. Use the correct pierce height for the material thickness, as prescribed in the owner’s manual. 4)Don’t forget the o-ring lube
(Fig. 4).
Use just enough lube to put a slight sheen on the o-rings. Too much lube will attract dirt and dust particles, while too little can result in a damaged o- ring. With a damaged o-ring, gas and coolant can mix inside the consumable chamber of the torch, reducing cut quality.
5)Do not add a circular lead-out when cutting holes (Fig. 5).
Once the torch has completed cut- ting the perimeter of a hole, the leftover center slug will drop out. On holes with a lead-out, this happens before the plasma power supply can perform an orderly shutdown of the arc. The arc instantly snaps off when the cutting current loses its path to ground, result- ing in a significant reduction in elec- trode life. Instead, use the nesting soft- ware to include a small amount of overburn to clean-up the hole.
6)Maintain proper air filtration.
Air supplied from a shop compressor often can be con- Fig. 6 taminated with dirt particles,
water, oil particulates and oil aerosol. Proper filtration is paramount to achieving optimum cut quality and consumable life. Moisture in the air can disrupt the plasma-gas mixture, resulting in a deformed arc, while oil particulates and oil aerosols can cause electrode, nozzle or even torch failure. 7)Remove material buildup from
the shield cap (Fig. 6).
If the torch drops down from the set pierce height too soon, or inadver- tently pierces too close to the work- piece, molten splatter can attach itself at or around the shield-cap orifice. Most times it can be removed easily using an abrasive hand pad (not sand- paper). If this spatter is not removed, it can lead to double-arcing, which can damage the electrode and nozzle. 8)Stay within prescribed process
parameters.
Do not attempt to pierce or cut material that is outside the capability of the selected amperage. This will greatly reduce the life of the shield cap, and possibly destroy the nozzle and
electrode in as little as one pierce.
9)Verify all consumable-part numbers.
Mixing up consumables from dif- ferent amperages will result in poor cut quality or misfires, and can cause immediate damage. Some cutting sys- tems automatically display the required consumables for the selected process, material, thickness and amperage. The owner’s manual also contains the cor- rect part numbers and pictures of each consumable.
10)Read the owner’s manual.
Often overlooked by operators, the owner’s manual provides a wealth of valuable information on proper equip- ment use and care. The manual often will include expert advice on a host of topics, including how to pierce thick material, edge starts, maximizing con- sumable life and inspecting consum- ables for damage. MF
Article provided by The Lincoln Elec- tric Co., Cleveland, OH, www.lincoln- electric.com.
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