Plasma Cutter Not Arcing: 7 Troubleshooting Methods

The stability of the arc in an NC plasma cutting machine is crucial for the quality of the cuts produced.

If the plasma arc is unstable, it can lead to problems such as uneven cuts, the buildup of edges, decreased performance of the control system components, and the need for frequent replacements of nozzles and electrodes.

Based on the analysis of this phenomenon, the solutions proposed are as follows:

1. Too high air pressure

If the input air pressure exceeds 0.45Mpa, it can have a negative impact on the plasma cutting process.

The excessive airflow will cause the plasma arc to disperse, weakening the concentration and intensity of the arc column, and reducing its cutting power.

Causes of high air pressure include:

• Improper input air conditioning
• Air filter pressure relief valve-regulated too high
• Air filter relief valve failed

The solution to the problem is:

• Verify that the air compressor pressure is set correctly.
• Check if the pressure between the air compressor and air filter pressure relief valve is in a proper and orderly state.
• If, after starting up, the air filter pressure reducing valve does not respond to adjustments made by rotating the switch and there is no change in the pressure reading on the gauge, this indicates that the air filter pressure reducing valve is not functioning properly and needs to be replaced.

2. Too low air pressure

When using a plasma cutting machine, if the working pressure is significantly lower than the required pressure specified in the specifications, this can negatively impact the cutting quality.

A low working pressure means a weakened plasma arc ejection speed and reduced input airflow, which will prevent the formation of a high-energy and high-speed plasma arc.

This can result in poor cutting quality, incomplete cuts, and the buildup of unwanted material on the cutting edge.

The causes of low air pressure include:

• The compressor is short of air
• The pressure adjustment of air conditioning valve of the plasma cutting machine is too low
• There is oil pollution in the electromagnetic valve
• The air channel is obstructed

The solution to the problem is:

Before operating the plasma cutting machine, it is crucial to inspect the air compressor’s output pressure display and make any necessary adjustments.

If the air pressure input meets the required standards, it is equally important to confirm that the air filter pressure relief valve is properly adjusted and the pressure display meets the plasma cutting requirements.

Proper maintenance of the air filter pressure relief valve must be performed regularly to guarantee the input air is clean and oil-free.

Contaminated air can cause oil buildup in the solenoid valve, making it challenging to open the valve core and leading to an insufficiently opened valve port.

When the torch nozzle pressure is too low, replacing the electromagnetic valve may be necessary.

A reduction in the gas channel cross-section can also lead to low air pressure. In such cases, the air tube can be replaced following the provided instructions.

3. Poor contact between ground wire and workpiece

Proper grounding is an essential step before using a plasma cutting machine.

If the appropriate grounding tool is not utilized, or if the workpiece surface is not properly grounded, the connection between the ground wire and the workpiece will be weak.

It is advisable to use specialized grounding tools to detect any insulation that could negatively impact the connection between the ground wire and the workpiece surface.

Using worn or old ground wires should be avoided.

4. Torch nozzles and electrodes burn out

The causes of premature damage of nozzle:

• Improper installation of the nozzle, such as untightened thread fastening
• Improper adjustment of all gears
• The cooling water doesn’t flow in as required when the cutting torch which needs to be cooled with water is working
• Frequent arcing

The solution to the problem is:

• Adjust the gear position correctly according to the technical requirement of cutting the workpiece
• Check whether the cutting torch nozzle is installed firmly
• Circulate the cooling water in advance if the nozzle needs to pass the cooling water
• When cutting, the distance between the cutting torch and the workpiece should be adjusted according to the thickness of the workpiece

5. The spark generator cannot automatically break the arc

When the plasma cutting machine is in use, the first step is to ignite the plasma arc.

The high-frequency oscillator triggers the gas between the electrode and the nozzle’s inner wall to form a high-frequency discharge that partially ionizes the gas and creates a small arc.

This small arc is then expelled from the nozzle by the compressed air, igniting the plasma arc.

This is the main function of the spark generator.

Typically, the spark generator operates for only 0.5 to 1 second.

If the arc cannot be automatically broken, it is usually because the components of the control circuit board are imbalanced or the gap between the spark generator’s discharge electrode is not set optimally.

The solution to the problem is:

• The discharge electrode of the spark generator should be checked frequently to keep its surface smooth
• Timely adjust discharge electrode gap of spark generator (0.8 ~ 1.2mm)
• Replace the control panel if necessary

6. The input AC voltage is too low

There are significant electrical facilities located on the site where the plasma cutting machine is used.

The malfunction of critical circuit components in the plasma cutting machine can result in an input AC voltage that is insufficient.

To address this problem, the following steps should be taken:

It is important to verify that the power grid connected to the plasma cutting machine has adequate load capacity and complies with the necessary power line specifications.

The plasma cutting machine should be located in a place that is distant from large electrical equipment and areas with electrical interference.

It is recommended to regularly clean dust and debris from components within the plasma cutter and check for worn wires during use.

7. Others

Aside from the previously mentioned causes, the stability of the plasma arc can also be impacted by factors such as a cutting speed that is too slow, the angle of the cutting torch in relation to the workpiece, and the operator’s level of expertise in using the plasma cutter. It is essential for users to keep these factors in mind.