Many things can cause issues when dealing with plasma consumable longevity. Troubleshooting these issues can be difficult, especially for those new to mechanized plasma cutting. The following is a list of some common problems and solutions to poor electrode and nozzle life.
One of the most frequent concerns people run into is that caused by an incorrect component in the consumable stack. Always double check the cut chart and part numbers to make sure ALL consumables are matched. Mismatched consumables will almost always cause premature failure and poor cut quality.
Wrong Cutting Parameters:
Modern CNC plasma cutting machines require a lot of settings like amperage, arc voltage, cut speed, etc. Thankfully, most systems use data bases with built in cut charts to simplify setting all the parameters. The operator is only required to choose a parameter set and the CNC will automatically adjust each setting correctly. The trick is to make sure you match the parameters with the material being cut and the proper consumables.
Coolant is another very important component to long consumable life. Using the proper coolant is critical, never use anti-freeze made for vehicles; these products have additives that will damage the cooling system and plasma torch. Coolant mixes with higher distilled water content will extend electrode life because water is more efficient at dissipating the heat.
Higher levels of glycol help to prevent freezing. Coolant flow is also critical to electrode life. Typically, a coolant system should pump at least 1 gallon per minute, but preferably 1 gallon in 45 seconds. A system without proper coolant flow will quickly cause the electrode to overheat and fail.
Gas plays a key role in the plasma process, besides pushing the arc through the nozzle orifice, gas helps to keep the nozzle cool. Insufficient gas flow will cause the nozzle to rapidly overheat and possibly melt. Additionally, the plasma gas needs to be clean, as well as moisture and oil free. Impurities in the gas can cause deposits to build up, resulting in blockages and double arcing.
The height of the torch plays a role in not only cut quality but consumable life. From the initial pierce height to the cut height, proper distance should be maintained. This will prevent damage to the consumables caused by splatter blowback, arc stretching, or torch crashing.
Thankfully, most modern CNC cutting systems use Arc Voltage Height Controls. AVHC automatically maintains the initial height set by the parameters entered at the start and, by using voltage sampling, maintains proper torch height throughout the cut. The trick here is to make sure that the operator chooses the correct parameters up front to match the consumables and material being cut.
Consumable life can easily be increased just by checking a few simple things such as matching proper consumables and parameters to the material being cut. Or by maintenance of coolant, and gasses, making sure that they are clean and functional. Also, things such as a properly operating torch height control and CNC will help you as you endeavor to get full life from your consumables.