Extending Consumable Life
Plasma cutting consumables include the shield, retaining cap, nozzle, electrode and swirl ring, however the nozzle and electrode are the most commonly replaced and the word “consumables” often refers to these. Knowing how and why they wear out will help you prevent premature wear and extend consumables life.
Monitor plasma gas pressure during cutting operation.
Plasma gas* pressure should remain as close as possible to the prescribed cutting charts and never differ more than +/- 5 PSI. Consult the equipment manual to determine optimum settings for your material and application.
Pressure too high (+5 PSI or higher) will cause the electrode to wear out faster than normal and require consumable change out and cutting table down time.
Pressure too low (-5 PSI or lower) will damage the nozzle orifice and effect the cut quality.
* The gas referred to is most often air, although fuel gas and oxygen are used for some applications.
Double check proper piercing height.
It can take the plasma arc as long as five seconds to cut through a plate. During this time the molten steel is pushed upwards, towards the shield cap, by the intensity of the gas pressure.
If the piercing height is too close to the plate, the arc can damage the shield cap.
If the piercing height is too far from the plate the arc may not pierce properly and cause a trailing arc throughout the cut. Misfires may start to take place, drastically reducing electrode life.
Beware of lead-out design when cutting holes.
As a plasma torch completes cutting a hole, the center disk will drop out. If the hole has a lead-out, the drop-out happens before the plasma power supply is able to shutdown the arc properly. The arc, trying to maintain contact with the falling disk, will stretch from the electrode, damage the nozzle (see image at right), and then snap off as the current loses its path to ground, significantly reducing electrode life.
Adjust your nesting software to add a little over-burn as the hole cutting process is completed.
Maintain proper air filtration.
Sometimes, air supplied from a compressor can be contaminated with oil or water. Even a tiny concentration of oil and water in the plasma stream can cause nozzle or electrode failure.
Remove any spatter from shield cap and torch.
If the torch pierces at the wrong height, spatter can bind itself around the opening of the shield cap (see image at left).
If the spatter is not removed, it can quickly damage the nozzle and the electrode.
For cutting thicker material that necessitates longer piercing times, a slight spray of anti-spatter on the shield face will help keep the spatter from sticking to the shield.
Follow prescribed feed-and-speed parameters.
Don’t try to cut or pierce through material that is not within the capability of the selected amperage. Doing so will have a significant negative impact on the shield cap and eventually damage the electrode and the nozzle.
To order or for more information:
1-941-753-7557 or 800-342-8477