The stability of the arc of the CNC plasma cutting machine directly affects the cutting quality. The instability of the plasma arc can lead to defects such as jagged indentation and accumulation of tumors. It also leads to a decrease in the life of related components of the control system, and frequent replacement of nozzles and electrodes.
1. High air pressure
If the input air pressure is far above 0.45 MPa, after the plasma arc is formed, the excessive air flow will blow the concentrated arc column, dispersing the energy of the arc column and weakening the cutting strength of the plasma arc. The causes of excessive air pressure are: improper input air conditioning, excessive adjustment of the air filter pressure reducing valve or failure of the air filter pressure reducing valve.
The solution is to check if the air compressor pressure is properly adjusted and whether the air compressor and air filter pressure reducing valve are out of pressure. After the power is turned on, such as the rotary air filter pressure reducing valve adjustment switch, there is no change in the gauge pressure, indicating that the air filter pressure reducing valve is malfunctioning and needs to be replaced.
2. Low air pressure
When the plasma cutting machine is working, if the working pressure is far lower than the pressure required by the specification, this means that the discharge 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 quality of the incision is poor, the cut is not penetrated, and the incision accumulates. The reasons for insufficient air pressure are: insufficient air input to the air compressor, low air pressure regulation of the air conditioner of the cutting machine, oil stain in the solenoid valve, and unobstructed air passage.
The solution is to observe the output pressure display of the air compressor before use. If the requirements are not met, adjust the pressure or repair the air compressor. If the input air pressure has reached the required level, check whether the air filter pressure reducing valve is adjusted correctly, and the gauge pressure display can meet the cutting requirements. Otherwise, the air filter regulator should be routinely maintained to ensure that the input air is dry and free of oil. If the input air quality is poor, oil will be generated in the solenoid valve, the valve plug will be opened, and the valve port will not open completely. In addition, if the pressure of the torch nozzle is too low, the solenoid valve needs to be replaced; if the cross section of the gas path becomes small, the air pressure will be too low, and the air pipe can be replaced according to the instructions.
3. Poor contact between the ground wire and the workpiece
Grounding is an essential preparation before cutting. If the special grounding tool is not used, the surface of the workpiece has insulation and the ground wire with severe aging for a long time will cause poor contact between the ground wire and the workpiece.
Special grounding tools should be used and checked for insulation that affects ground wire contact with the workpiece surface, avoiding the use of aged grounding wires.
4. Torch nozzle and electrode burnout
If the nozzle is not properly installed, if the thread is not tightened, the gears of the equipment are not properly adjusted. If the torch that needs water cool is not working, the flowing cool water and frequent arcing will cause premature nozzle damage. The solution is to correctly adjust the gears of the equipment according to the technical requirements of cutting the workpiece, and check whether the nozzle of the torch is installed firmly. The nozzle that needs to pass the cool water should circulate the cool water in advance. When cutting, adjust the distance between the torch and the workpiece according to the thickness of the workpiece.
5. Spark generator cannot automatically break arc
When the plasma cutting machine is working, the plasma arc is first ignited, 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, so that the gas is locally ionized to form a small arc, which is compressed by the air. The action, which is ejected from the nozzle to ignite the arc, 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. The reason why the arc cannot be automatically broken is generally to control the offset of the circuit board components, and the discharge electrode gap of the spark generator is not suitable.
Always check the spark generator discharge electrode to keep the surface flat, adjust the discharge electrode gap of the spark generator (0. 8 ~ 1. 2mm), and replace the control board if necessary.
6. Input AC voltage is too low
The use of the plasma cutting machine has large-scale power facilities, and the main circuit components inside the cutting machine are faulty, which causes the input AC voltage to be too low.
The solution is to check whether the plasma cutting machine is connected to the grid and has sufficient carrying capacity, and whether the power cord specifications meet the requirements. The plasma cutting machine should be installed away from large electrical equipment and places with frequent electrical interference. During to use, regularly clean the dirt and components on the cutting machine, and check if the wires are aging.
In addition to the above reasons, the cutting speed is too slow, the perpendicularity of the torch and the workpiece during cutting, as well as the operator's familiarity with the plasma cutting machine, the operating level, etc., all affect the stability of the plasma arc, the user should pay attention to these aspects!