Causes and solutions for arc failure in plasma cladding

The problem of arc failure in plasma cladding is usually more complicated than that in ordinary arc welding, because it involves the coordinated work of the powder delivery system, plasma arc stability and gas system. The following are the specific reasons and solutions:

1. Power system problem

reason:

Abnormal power output: power failure or insufficient output voltage.

Improper arc starting voltage setting: The voltage required for arc starting is not reached.

Control circuit problem: control module or trigger circuit fault.

Solution:

Check that the power supply is functioning properly, measure the output voltage and ensure it is within the specified range for the device.

Adjust the arc starting voltage to the recommended value (adjust according to the equipment specifications).

Check the control module circuit board, troubleshoot, and replace damaged components if necessary.

2. Gas system problems

reason:

Insufficient or interrupted shielding gas: low pressure in gas cylinder or blocked gas pipeline.

Plasma arc gas flow is too large or too small: a stable plasma arc cannot be formed.

Nozzle is clogged or damaged: causing uneven airflow or obstructed gas flow.

Solution:

Check the gas cylinder pressure to ensure that there is sufficient gas, and adjust the flow rate of the shielding gas and plasma gas (the flow rate value is adjusted according to the equipment manual, generally argon or argon-hydrogen mixture).

Clean or replace the nozzle to ensure that the air path is unobstructed.

Check that all pipe connections are tight and leak-free.

3. Powder delivery system problems

reason:

Poor powder delivery: The powder delivery pipe is blocked or the delivery is unstable.

Powder quality problems: Powder particles are too large, uneven, or contain moisture and impurities.

Powder nozzle wear: causes powder to be unable to be accurately delivered into the molten pool.

Solution:

Check the powder delivery pipeline, clear the blocked parts and ensure smooth flow of powder.

Make sure to use high-quality metal powder that meets process requirements. The powder particle size is usually 15-45 μm and it should be kept dry.

Regularly check and replace worn powder nozzles to ensure accurate spray direction and flow.

4. Electrode or nozzle problem

reason:

Tungsten electrode wear: The top of the electrode has an abnormal shape or is severely worn.

Incorrect spacing between electrode and nozzle: spacing that is too large or too small affects arc ignition.

Nozzle damage: The nozzle aperture is deformed or blocked, resulting in unstable arc.

Solution:

Check and grind the top of the tungsten electrode to ensure that the top is complete and meets the requirements.

Adjust the distance between the electrode and the nozzle, usually the distance is 1-3 mm.

Replace damaged nozzles, making sure the nozzle aperture matches the equipment.

5. Workpiece grounding problem

reason:

The grounding clamp has poor contact: the grounding clamp is loose or the surface is oxidized.

The workpiece surface is not clean: oil, oxide layer or other impurities affect conductivity.

Solution:

Check the ground clamp to make sure it is tight and making good contact.

Clean the workpiece surface to remove oil, oxide layer and impurities.

6. Parameter setting issues

reason:

Improper current or voltage settings: welding current, arc voltage and other parameters are not within the recommended range.

The gas delay setting is unreasonable: the gas pre-flow or post-flow time is insufficient.

Solution:

Adjust welding parameters according to the process manual to ensure that welding current and arc voltage are within the standard range.

Adjust the gas pre-flow and post-flow time, usually the pre-flow time is 1-5 seconds.

7. Environmental or equipment problems

reason:

Cooling system failure: insufficient flow or too high temperature in the water cooling system.

Ambient humidity is too high: The inside of the device is damp, affecting circuit operation.

Equipment aging or component damage: The internal components of the welding machine age after long-term use.

Solution:

Check the cooling water circulation system to ensure that the flow and temperature meet the requirements.

Use a dehumidifier in humid environments to keep the equipment dry.

Check equipment regularly and repair or replace aging components.

8. Operational issues

reason:

Improper arc striking operation: improper arc striking angle or distance.

Powder delivery is not synchronized with the arc: powder enters the weld pool too early or too late.

Solution:

Make sure the angle between the welding gun and the workpiece is appropriate when striking the arc, and the distance is generally kept at 2-5 mm.

Adjust the powder delivery time to synchronize with the arc ignition and welding process.

Summarize

Arc failure in powder plasma cladding is usually caused by problems with power supply, gas circuit, powder delivery, nozzle or parameter setting. When solving the problem, check in the following order:

Power system: Check circuit and output voltage.

Gas system: ensure that gas flow and purity meet the requirements.

Powder delivery: Check powder quality and delivery system.

Electrode and nozzle: Replace damaged electrode or nozzle.

Parameter setting: adjust welding current, arc voltage and gas delay.

Regularly maintaining equipment and operating in strict accordance with process requirements can effectively reduce the occurrence of similar problems.

Plasma cladding