Case 1: Electrode loss, nozzle loss
When the consumables were inspected, the electrodes and nozzles were found to be severely worn out, which may be the nozzle loss caused by the electrodes. Because the plasma arc generated by the electrode passes through the nozzle, the resulting melt enters the nozzle, and in the long run, all consumables are damaged. If the pits of the electrodes are deep, the copper body will turn blue or black due to overheating, possibly because the cooling flow is too slow. In severe cases, the ends of the electrodes will be melted.
Check the flow rate of the cooling medium and check the cooling flow rate of the water-cooled torch with a bucket test back to the cooling water tank. If it is different from the specifications, check the pump problem, whether the water pipe is kinky or leaking, whether the filter device is blocked or other problems. The air-cooled torch checks if the gas flow is too slow. If the end face of the electrode has a small pitting, and the inside of the nozzle is also damaged, the flow is low. In the case of low airflow, the arc is uncontrollable between the nozzle and the electrode. The best way to check the airflow rate of the torch is to use a flow meter (0-400 cfh) and a gas pipe at the gas outlet of the torch to test with the system. If not, the quick check method is to feel the gas flow at the gas outlet of the torch only when the plasma gas is turned on. At this time, it can be felt that the vortex gas is actually suction. If the electrode surface has a black residue, check the gas purity. The quick method is the paper towel test method: put a clean paper towel under the cutting gun, blow through the system, the torch, there should be no moisture or pollutants on the paper.
Case 2: The electrode is intact and the nozzle is worn out.
If the electrode is almost new and the nozzle is bad, the most likely cause is that the nozzle has a double arc. If the plasma arc contacts the nozzle, the copper material at the nozzle opening is melted. Damage inside the nozzle (such as a groove or perforation) indicates that the plasma pressure is too low so that the plasma arc can contact the nozzle. Check the air circuit for leaks through the booster. Check all the devices with soapy water. External damage to the nozzle is often a problem with the height of the torch to the cutting workpiece. First, check the height of the perforation, which should be twice the height of the cut, so as to avoid splashing slag, which is the first cause of nozzle damage. Check the appropriate torch height control. If the torch hits the plate during piercing or cutting, the nozzle will quickly break. If the nozzle heats up, turns blue or black, check the protective gas path, which helps cool the nozzle and protect the front end of the torch.
Case 3: The electrode is damaged and the nozzle is intact.
If the nozzle is good, the electrode has deep concentric pits and the plasma gas flow rate may be too high. If the vortex gas is too large, the material consumption will be faster. This will result in rapid electrode wear and should be checked for plasma gas flow.
If the consumables appear to be new, and the torch can't arc, the new consumables can arc, and the problem is not the consumable life problem, which is forced arcing. Forced arcing is due to excessive plasma pressure. Usually, good electrodes and good nozzles will be damaged due to arc failure. We will hear a click when the torch is arcing.
Increasing the service life of consumables not only saves costs, but also improves cutting efficiency and cutting quality, which increases profitability for manufacturers, and correct judgment and use of consumables will bring new value.
Post time: Sep-02-2019
