Extending the Life
of Plasma Consumables

This article is reproduced with permission
of Canadian Machinery and Medalworking.

Shield cups, electrodes and cutting tips all wear out—that is why they're called consumables.
If you know how and why they wear out, though, you can prevent premature wear.

Consumable life on air plasma cutting torches depends on many factors, including cutting amperage, cutting speed, air quality, humidity and
operator skill. For maximum performance, the tip and electrode should be changed at the same time. To extend the life of these consumables,
it helps to know how they work. Here is a closer look.

Cutting Tips

The orifice in a torch-cutting tip is designed to constrict the plasma arc to a specific diameter , without the arc touching the nozzle. The plasma gas
provides a thin boundary layer of cooler gas between the arc and the nozzle. If the current level is turned up too high or the gas flow rate is too slow,
the arc may contact the cutting tip. If this happens, then current flows to the work piece through the cutting tip itself—not just through the plasma arc.
This is called double arcing and it damages the cutting tip. You will know when this occurs because it leaves gouges in the cutting tip. Also, the orifice
will no longer correctly constrict the arc, which means a poorly focused, weakened arc and a sloppy cut.

Electrodes

Every time an arc is struck, the electrode receives a current surge that brings it from a cold state to an extremely hot state very quickly. The ionized
plasma gas flowing past the electrode is full of charged particles. These particles pull atoms away from the hot surface of the electrode, which wears
away the emitting element and creates a pit in the surface

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