The quality of cutting is inseparable from the stability of the arc of the plasma cutting machine. In other words, the stability of the arc of the plasma cutting machine directly affects the cutting quality. The instability of the plasma arc will cause defects such as uneven incision and accumulation. It will also lead to a reduction in the life of the related components of the control system, and frequent replacement of nozzles and electrodes. In view of this phenomenon, analyze and propose solutions.
1. The air pressure is too low
When the plasma cutting machine is working, if the working air pressure is far lower than the air pressure required by the manual, it means that the ejection speed of the plasma arc is weakened, and the input air flow rate is less than the specified value. At this time, a high-energy, high-speed plasma arc cannot be formed. As a result, the incision quality is poor, the incision is not penetrated, and the incision is accumulated. The reasons for the lack of air pressure are: insufficient input air from the air compressor, too low pressure regulation of the air regulating valve of the cutting machine, oil pollution in the solenoid valve, and unobstructed air path.
The solution is to observe the output pressure display of the air compressor before use. If it does not meet the requirements, you can adjust the pressure or repair the air compressor. If the input air pressure has reached the requirements, check whether the adjustment of the air filter pressure reducing valve is correct, and whether the gauge pressure display can meet the cutting requirements. Otherwise, routine maintenance should be performed on the air filter pressure reducing valve to ensure that the input air is dry and free of oil. If the input air quality is poor, it will cause oil pollution in the solenoid valve, the valve core is difficult to open, and the valve port cannot be fully opened. In addition, if the air pressure of the torch nozzle is too low, it is necessary to replace the solenoid valve; if the gas path section becomes smaller, the air pressure will also be too low, and the air pipe can be replaced according to the instructions.
2. The air pressure is too high
If the input air pressure is far more than 0.45MPa, after the plasma arc is formed, the excessive airflow will blow away the concentrated arc column, disperse the energy of the arc column, and weaken the cutting strength of the plasma arc. The reasons for the high air pressure are: improper adjustment of the input air, excessive adjustment of the air filter pressure reducing valve or failure of the air filter pressure reducing valve.
The solution is to check whether the pressure of the air compressor is adjusted properly, and whether the pressure of the air compressor and the air filter pressure reducing valve is out of balance. After turning on the machine, if the air filter pressure reducing valve is turned to adjust the switch, the gauge pressure does not change, indicating that the air filter pressure reducing valve is out of order and needs to be replaced.
3. Torch nozzle and electrode burnout
Due to improper installation of the nozzle, such as the thread is not tightened, the gears of the equipment are improperly adjusted, and the cutting torch that needs to be cooled by water does not pass the flowing cooling water as required and frequently starts arcing when the cutting torch is working, which will cause the nozzle to be damaged prematurely.
The solution is to correctly adjust the gears of the equipment according to the technical requirements of the cutting workpiece, check whether the torch nozzle is installed firmly, and the nozzles that need to pass the cooling water should circulate the cooling water in advance. When cutting, adjust the distance between the torch and the workpiece according to the thickness of the workpiece.
4. The input AC voltage is too low
There are large-scale electrical facilities at the use site of the plasma cutting machine, and the failure of the main circuit components inside the cutting machine will cause the input AC voltage to be too low.
The solution is to check whether the power grid connected to the plasma cutting machine has sufficient carrying capacity and whether the specifications of the power cord meet the requirements. The installation location of the plasma cutting machine should be far away from large electrical equipment and places with frequent electrical interference. During use, regularly clean the dust in the cutting machine and the dirt on the components, and check whether the wires are aging.
5. Poor contact between the ground wire and the workpiece
Grounding is an essential preparation before cutting. If no special grounding tool is used, there is insulation on the surface of the workpiece, and long-term use of the ground wire with serious aging will cause poor contact between the ground wire and the workpiece.
Special grounding tools should be used, and check whether there is any insulation that affects the contact between the ground wire and the surface of the workpiece, and avoid using an aging ground wire.
6. The spark generator cannot automatically cut off the arc
When the plasma cutting machine is working, the plasma arc must be ignited first, and the gas between the electrode and the inner wall of the nozzle is excited by the high-frequency oscillator to generate a high-frequency discharge, which ionizes the gas locally to form a small arc, which is affected by the compressed air. It is sprayed from the nozzle to ignite the plasma arc, which is the main task of the spark generator. Under normal circumstances, the working time of the spark generator is only 0.5 ~ 1s, and the reason why the arc cannot be automatically interrupted is generally that the control circuit board components are out of balance, and the discharge electrode gap of the spark generator is not suitable.
7. Poor contact between the ground wire and the workpiece
Grounding is an essential preparation before cutting. If no special grounding tool is used, there is insulation on the surface of the workpiece, and long-term use of the ground wire with serious aging will cause poor contact between the ground wire and the workpiece.
Special grounding tools should be used, and check whether there is any insulation that affects the contact between the ground wire and the surface of the workpiece, and avoid using an aging ground wire.
8. The spark generator cannot automatically cut off the arc
When the plasma cutting machine is working, the plasma arc must be ignited first, and the gas between the electrode and the inner wall of the nozzle is excited by the high-frequency oscillator to generate a high-frequency discharge, which ionizes the gas locally to form a small arc, which is affected by the compressed air. It is sprayed from the nozzle to ignite the plasma arc, which is the main task of the spark generator. Under normal circumstances, the working time of the spark generator is only 0.5 ~ 1s, and the reason why the arc cannot be automatically interrupted is generally that the control circuit board components are out of balance, and the discharge electrode gap of the spark generator is not suitable.
The discharge electrode of the spark generator should be checked frequently to keep its surface flat, and the discharge electrode gap (0.8-1.2mm) of the spark generator should be adjusted in time, and the control board should be replaced if necessary.
9. Others
In addition to the above reasons, the cutting speed is too slow, the perpendicularity of the cutting torch and the workpiece during cutting, as well as the operator's familiarity with the plasma cutting machine, operation level, etc., all affect the stability of the plasma arc, and the user should pay attention to these aspects.
