Failure reason and solution of plasma cutting arcs 
The stability of plasma cutting arc directly affects the cutting quality, plasma arc instability, will lead to uneven incision, tumor and other defects, but also lead to the control system related components life is reduced, nozzles, electrodes frequently replaced. In view of this phenomenon, analysis and solutions are proposed.
1. The air pressure is too low
Plasma cutting machine work, such as the working air pressure is far lower than the air pressure required by the instruction manual, which means that the plasma arc equip speed is reduced, the input air flow is less than the specified value, at this time can not form a high-energy, high-speed plasma arc, resulting in poor cut quality, impermeable, indipation tumor phenomenon. The reasons for the lack of air pressure are: air compressor input air is insufficient, cutting machine air conditioning valve pressure is too low, solenoid valve oil pollution, air flow is not smooth and so on.
The solution is to observe the air compressor output pressure display before use and adjust the pressure or access the air compressor if it does not meet the requirements. If the input air pressure has reached the requirements, should check that the air filtration relief valve is correctly adjusted, the table pressure display can meet the cutting requirements. Otherwise, the air filtration relief valve should be routinely maintained to ensure that the input air is dry and free of oil. If the input air quality is poor, it will cause oil contamination in the solenoid valve, the valve core is difficult to open, the valve port can not be fully opened. In addition, the torch nozzle air pressure is too low, also need to replace the solenoid valve;
2. The air pressure is too high
If the input air pressure is much higher than 0.45MPa, after the formation of the plasma arc, the large air flow will blow away the concentrated arc column, so that the arc column energy dispersion, reducing the cutting strength of the plasma arc. Causes of excessive air pressure are: improper input air regulation, air filtration pressure relief valve regulation is too high, or air filtration relief valve failure. The solution is to check that the air compressor pressure is adjusted properly and that the pressure of the air compressor and air filtration relief valve is not correct. After powering on, such as rotating air filter relief valve adjustment switch, table pressure does not change, indicating that the air filter relief valve failure, need to be replaced.
3. Torch nozzle and electrode burn damage due to improper nozzle installation, such as wire buckle is not tight, equipment gear adjustment is not correct, the torch needs to be cooled with water at work, not as required into the flow of cooling water and frequent arcing, will cause premature damage to the nozzle.
The solution is, in accordance with the technical requirements of cutting work parts, correctly adjust the equipment gear, check whether the torch nozzle is installed, the nozzle that needs to pass the cooling water should be in advance to circulate the cooling water. When cutting, adjust the distance between the torch and the work piece according to the thickness of the work piece.
4. Input AC voltage is too low plasma cutting machine use site has large-scale electrical facilities, cutting machine internal main circuit component failure, etc. , will make the input AC voltage too low. The solution is to check that the plasma cutter is connected to the grid with sufficient carrying capacity and that the power cord specifications meet the requirements. Plasma cutter installation site, should be away from large electrical equipment and often electrical interference. During use, regularly clean the cutting machine dust and dirt on the components, check the wire aging phenomenon.
5. Poor grounding of ground contact with work parts is an essential preparation before cutting. Without the use of special grounding tools, insulation on the surface of the work piece and long-term use of severe aging ground, etc., will make the ground line and the work parts in poor contact. Special grounding tools should be used and check for insulation that affects ground contact with the work surface and avoid the use of aging ground wires.
6. Spark generator can not automatically break the arc plasma cutting machine work, first of all, ignite the plasma arc, by the high-frequency oscillator to excite the gas between the electrode and the inner wall of the nozzle, produce a high frequency discharge, so that the gas partial ionization and form a small arc, this small arc by the role of compressed air, from the nozzle sprayed to ignite and so on away from the arc, which is the main task of the spark generator. Under normal circumstances, the spark generator operating time is only 0.5 to 1s, can not automatically break the arc is generally the reason for the control circuit board components imbalance, spark generator discharge electrode clearance is not suitable. The spark generator discharge electrode should be checked frequently to keep its surface level, and the discharge electrode gap (0.8 to 1.2mm) of the spark generator should be adjusted in due course, and the control panel should be replaced if necessary.
7. In addition to the above reasons, cutting speed is too slow, the verticality of the torch and work parts when cutting, as well as the operator's familiarity with the plasma cutting machine, operating level, etc., all affect the stability of the plasma arc, the user should pay attention to these aspects.
