Common troubleshooting of CNC plasma cutter

Common troubleshooting of CNC plasma cutter

If you encounter a failure during the use of the CNC plasma cutter, you should carefully ask the operator about the cause of the failure and the symptoms after the failure. When a variety of problems are intertwined, there is no way to start. Now, Huafei CNC will explain how to deal with the failure of the CNC plasma cutter.

cnc plasma cutters crossbeam

1. Tracking error alarm

(1) During work, the electromagnetic arc of the plasma cutting machine will generate high-frequency electromagnetic pulses, which will interfere with the equipment and the numerical control system, thereby causing the loss of preset parameters, and the machine tool microprocessor can not work normally. The solution is to use repeated grounding measures for the equipment shell and the grounding point in the machine, and use a dedicated line for power supply.
(2) There are large-scale punching machines or butt-welding machines and other high-power equipment near the cutting machine. They will affect the quality of power supply when they are working and often make the input voltage transiently low. When the voltage fluctuation is greater than 15%, the voltage regulator is too late to adjust, and the error registers of the X, Y, and Z axes are wrong, causing the system to interrupt. The method of disarming the alarm is: power off—start on power—return to zero.

cnc plasma cutters servo motor

2. Servo drive alarm

(1) The power control voltage is abnormal. Measure the No. 5 and No. 7 pins of the servo cable. The voltage should be +12 V.
(2) The feed speed is too fast, causing the servo transformer to overheat (you can feel it by hand). Stop cutting at this time, and start after cooling for 20-30 minutes.
(3) The feedback signal of the servo motor is disconnected. During the inspection, the X and Y servo cables can be exchanged, and the alarm information can be read after turning on the machine.
(4) The synchronization signal circuit is faulty. At this time, it will be accompanied by the vibration of a certain axis of the motor. You can separately add a +5V DC power supply to this circuit and use an oscilloscope to measure the input and output of each chip one by one, and compare it with the logic function it should have. Compare, to check the quality of the chip; Use a multimeter to compare whether the resistances of the three primary and three secondary sides of the synchronous transformer are the same to check the synchronous transformer and the noise filter circuit.

cnc plasma cutter no automatic drop

3. The cut is rough and does not automatically blank

(1) Due to the influence of temperature, the amplifying element in the position detection circuit in the cutting torch has a zero drift, and the distance between the cutting torch and the workpiece will also change slightly so that the energy of the cutting flame cannot be concentrated on the cutting gap of the workpiece. It completely melts to produce this phenomenon.
(2) The position of the cutting torch is determined by the capacitance value between the iron sheet installed at the cutting nozzle and the workpiece. After long-term use, the iron slag will splash on the iron sheet of the detection capacitor, which will affect the capacitance value and cause The torch frequently shakes, which causes this phenomenon.
(3) After long-term use, on the one hand, the cutting nozzle will rub against the slag on the workpiece, which will loosen the connecting nut and joint of the cutting torch. During the cutting process, the cutting torch and the workpiece are difficult to maintain verticality, causing both Misalignment, misalignment; On the other hand, the backlash of the lead screw increases, and the cutting torch cannot be positioned correctly. At this time, the corresponding machine tool system parameters should be modified to increase the correction of the actual machining error.

cnc plasma cutter plasma torch

4. No arc ignition

(1) The compressed air has too heavy moisture or low gas pressure. The solution is: pay attention to the output pressure display of the air compressor before use, if it does not meet the requirements, you can adjust the pressure or overhaul the air compressor. If the input air pressure has reached the requirements, check whether the adjustment of the air pressure reducing valve is correct and whether the gauge pressure display can meet the cutting requirements. Otherwise, daily maintenance should be carried out on the airflow pressure reducing valve to ensure that the input air is dry and free of oil.
(2) The distance between the cutting nozzle and the electrode is too large. During the inspection, the small mirror can be placed at the cutting nozzle with the mirror face up to observe the imaging. The solution is to properly grind off the magnetic sleeve.
(3) After the equipment has been running for a period of time, due to the fouling on the reed or the friction between the reed and the cavity wall, the pressure relay often fails due to the stuck reed, resulting in the control circuit not working and not starting the arc.
(4) The discharge mica capacitor on the main circuit of the cutting machine is damaged, causing the inter-electrode discharge to fail during arc ignition.
(5) The cutting torch is adjusted improperly, or the thimble supporting the workpiece is broken, the workpiece is sunken, and the cutting torch is too far away from the steel plate, which may also cause malfunction.

cnc plasma cutter plasma and flame torch

5. The electrode nozzle is damaged faster

(1) The voltage is unstable. The electrode contains a nickel-chromium alloy. When the voltage is high, the alloy is easy to wear; when the voltage is low, it will quickly volatilize due to the current drawn.
(2) The cutting tip is not aligned with the electrode.
(3) The small hole on the electrode is blocked by splashing molten slag.
(4) After the tap water in the cooling system is used for a period of time, a large amount of scale will accumulate in the water pipe, resulting in insufficient water pressure, poor water flow, and insufficient cooling of the electrode nozzle. Long-term continuous cutting will cause heat at the electrode nozzle. It cannot be dissipated as quickly as possible, which will also deform the electrode tip due to overheating.

cnc plasma cutters plasma torch

6. The torch is electrified after stopping cutting

(1) AC power flees into the transformer. Solution: Replace the transformer with a relay whose coil voltage is AC 120V.
(2) There is residual magnetism in the transformer coil. A resistance-capacitance loop can be connected in parallel to the secondary of the coil, and the capacitance is 10μF/6V to release the residual magnetic energy quickly.
(3) The reeds of the transformer will produce strong sparks when they are in action, so the contacts are stuck due to the melting of the silver-plated layer so that the circuit cannot be opened normally.

cnc plasma cutter air pressure gauge

7. 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 arc column energy, and weaken the cutting strength of the plasma arc. The reasons for the high air pressure are improper input air regulation, over-adjustment of the air pressure relief valve, or failure of the air pressure relief valve. The solution is: check whether the pressure of the air compressor is adjusted properly, 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.

cnc plasma cutter cnc system

8. Problems that should be paid attention to in automatic programming

After the machine tool, the numerical control system is connected with the microcomputer, it can automatically program according to the input graphics and the specified cutting work path. But still, need to pay attention to the following issues:
(1) When cutting several pieces of the same product on the same iron plate, manually add the G00G91X2Y2 command at the end of the automatic programming program to ensure continuous cutting. Otherwise, the cutting torch of the machine tool only runs repeatedly on the original coordinate trajectory.
(2) In the automatically generated program, all transitions between lines are sharp corner transitions by default. Therefore, when cutting an arc, pay attention to changing the turning point to an arc transition.
(3) The cut of the workpiece has a certain width, and the automatic programming does not consider the error caused by this. Therefore, for workpieces of different thicknesses and different cutting speeds, the width of the slit must be manually adjusted in the program makeup.

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