Influence of cnc plasma cutting machine arc stability

Let’s take a look at the plasma cutting machine equipment today.

    1. The spark generator cannot automatically cut off the arc
    When the plasma cutting machine is working, the plasma arc must first be ignited. The high-frequency oscillator excites the gas between the electrode and the inner wall of the nozzle to generate a high-frequency discharge, which partially ionizes the gas to form a small arc. This small arc is affected by compressed air. Function, eject 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 to 1 s, and the reason for the failure to automatically cut off the arc is generally the imbalance of the control circuit board components, and the discharge electrode gap of the spark generator is not suitable.

    Always check the discharge electrode of the spark generator to keep its surface flat, adjust the discharge electrode gap (0.8～1.2mm) of the spark generator in a timely manner, and replace the control board if necessary.

    2. The air pressure is too high
    If the input air pressure far exceeds 0 or 45MPa, after the plasma arc is formed, the excessive airflow will blow away the concentrated arc column, disperse the arc column energy, and weaken the cutting strength of the plasma arc. The reasons for the excessively high air pressure are: improper input air adjustment, 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 adjustment. After starting up, if you turn the air filter pressure reducing valve adjustment switch, the gauge pressure does not change, indicating that the air filter pressure reducing valve has failed and needs to be replaced.

    3. The air pressure is too low
    When the plasma cutting machine is working, if the working pressure is far lower than the pressure required by the instructions, this means that the ejection speed of the plasma arc is weakened, and the input air flow is less than the specified value. At this time, high-energy and high-speed plasma arcs cannot be formed. As a result, the quality of the incision is poor, the incision is impervious, and the incision is built up. The reasons for the insufficient air pressure are: insufficient air input from the air compressor, too low pressure adjustment of the air regulating valve of the cutting machine, oil stains in the solenoid valve, and unsmooth air path.

    The solution is to observe the output pressure display of the air compressor before use. If it does not meet the requirements, adjust the pressure or overhaul 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, the air filter pressure reducing valve should be maintained daily 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 cutting torch nozzle is too low, the solenoid valve needs to be replaced; the reduction of the air path section will also cause the air pressure to be too low. The air pipe can be replaced according to the instructions.

    The solution is to correctly adjust the gears of the equipment according to the technical requirements of cutting the workpiece, check whether the torch nozzle is installed firmly, and the nozzle that needs 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 internal main circuit components of 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 power cord specifications meet the requirements. The installation location of the plasma cutting machine should be far away from large-scale electrical equipment and places with frequent electrical interference. During use, clean the dust in the cutting machine and the dirt on the components regularly, and check whether the wires are aging or not.

    5. Burning torch nozzle and electrode
    Due to improper installation of the nozzle, such as the thread is not tightened, the gears of the equipment are not adjusted properly, the torch that needs water cooling is working, the flow of cooling water is not passed as required, and the frequent arcing will cause the nozzle to be damaged prematurely.

    6. Poor contact between the ground wire and the workpiece
    Grounding is an essential preparation before cutting. If a dedicated grounding tool is not used, insulation on the surface of the workpiece and long-term use of a ground wire with serious aging, etc., will cause poor contact between the ground wire and the workpiece.

    Special grounding tools should be used, and check whether there is any insulation affecting the grounding wire and the surface of the workpiece, and avoid using aging grounding wires.

    7. Other
    In addition to the above reasons, the cutting speed is too slow, the perpendicularity of the cutting torch and the workpiece during cutting, and the operator's familiarity with the plasma cutting machine, operation level, etc., all affect the stability of the plasma arc. The user should pay attention to these aspects. .