What is the function of plasma welding equipment?

Plasma welding equipment is a high-precision welding technology that uses a plasma arc as a heat source. By ionizing gas to form a high-temperature plasma (reaching 30,000°C), it achieves efficient metal welding. Its core function is to address difficult, high-precision welding requirements that are difficult to achieve with traditional welding methods. It is particularly indispensable in fields such as aerospace, nuclear power, and precision manufacturing.

1. The Core Function of Plasma Welding

High-energy welding, suitable for difficult-to-weld materials

It can weld metals with high melting points and high thermal conductivity, such as stainless steel, titanium alloys, and nickel-based alloys, as well as refractory metals such as tungsten and molybdenum.

It is suitable for welding thin plates (ultra-thin materials as thin as 0.1mm) to thick plates (with a single penetration depth of over 10mm).

Precise control reduces thermal deformation

The plasma arc features concentrated energy, a thin arc column (1-3mm diameter), and a small heat-affected zone, significantly reducing workpiece deformation. It is suitable for precision parts such as sensors and medical devices.

Automation compatibility improves efficiency

Can be integrated with robotic arms and CNC systems to achieve high-speed continuous welding (e.g., automated production lines for automotive exhaust pipes).

Versatile process coverage

Supports specialized processes such as micro-beam plasma welding (current as low as 0.1A), perforated plasma welding (single-sided welding and double-sided forming), and cladding (surface repair).

2. Common Problems with Plasma Welding Equipment

• Arc Unstable or Difficulty Ignition

Possible Causes

Gas Problems:

Shielding gas (argon/hydrogen) purity is insufficient or the flow rate is unstable.

Gas line leaks or is clogged.

Electrode Wear:

Tungsten electrode (or cerium tungsten electrode) is severely worn or improperly installed.

Power Supply Problems:

High-frequency arc starter failure or power supply voltage fluctuations.

Workpiece Contamination:

Oil, oxide layer, or moisture on the weld surface.

Solutions: Check the gas supply: Ensure gas purity is ≥99.99% and adjust the flow rate (usually 8-12 L/min for main gas and 2-5 L/min for shield gas).

Replace the electrode: Use a sharp tungsten electrode and ensure it is concentric with the nozzle.

Cleaning the workpiece: Remove surface contaminants with acetone or sandpaper.

Check the power supply: Test the high-frequency arc ignition function and ensure proper grounding.

• Porosity or Slag Inclusion in the Weld

Possible Causes

Inadequate Gas Shielding:

Shielding gas flow rate is too low or the nozzle is clogged.

Draught in the welding environment (impairing gas coverage).

Material Issues:

Impurities in the base metal or welding wire (such as sulfur or phosphorus).

Incorrect Process Parameters:

Welding speed is too fast or the current is unstable.

Solutions:

Optimize gas shielding: Increase shielding gas flow rate and use a drag hood or back shielding gas (especially important when welding titanium alloys).

Adjust parameters: Reduce welding speed and increase current appropriately (to ensure adequate weld pool flow).

Material Pretreatment: Select high-purity welding consumables and preheat the workpiece in a humid environment.

• Rapid Nozzle or Electrode Burnout

Possible Causes:

Inadequate Cooling:

Water cooling system malfunction or insufficient flow.

Incorrect Gas Ratio:

Excessive hydrogen content (although hydrogen enhances energy, it accelerates electrode oxidation).

Excessive Current:

Exceeding the rated load of the nozzle/electrode.

Solutions: Check the cooling system: Ensure the water pressure is normal (usually 0.3-0.5 MPa) and there are no blockages. Adjust the gas mixture ratio: The hydrogen content in the argon-hydrogen mixture should not exceed 5%-8%.

Reduce the current: Refer to the equipment manual for rated parameters to avoid prolonged overload operation.

• Poor weld formation (undercut, lack of fusion)

Possible Causes

Alignment deviation:

Incorrect welding torch angle to workpiece (ideal angle: 75°-90°).

Parameter mismatch:

Improper current, voltage, or wire feed speed settings.

Workpiece assembly issues:

Excessive groove gap or misalignment.

Solution: Calibrate the welding torch position: Use a laser positioning fixture to ensure alignment.

Optimize parameters: Use a low current (e.g., 30-50A) for thin plates; multiple passes are required for thick plates.

Strict assembly: Maintain gaps ≤ 0.1mm and add filler wire as necessary.

• Automatic equipment shutdown or alarm

Possible Causes

Overheating protection:

Cooling system failure or excessively high ambient temperature.

Power failure:

Overload, short circuit, or poor grounding. Insufficient gas pressure:

Low gas cylinder pressure or solenoid valve malfunction.

Solution:

Check the alarm code: Identify the specific cause according to the equipment manual.

Restart the cooling system: Clean the filter and refill the coolant.

Test the power supply circuit: Avoid sharing the circuit with other high-power equipment.

• Excessive welding spatter

Possible causes:

Improper current pulse setting:

The pulse frequency or base current is too low.

Material mismatch:

The melting point of the welding wire and the base material differ significantly (for example, welding aluminum to stainless steel).

Solution:

Adjust the pulse parameters: Increase the pulse frequency or reduce the peak current.

Replace the welding wire: Select a filler material that is compatible with the base material.

3. Key points for maintaining plasma welding equipment