Plasma welding of metal

Plasma welding  Plasma welding is a high-tech metal joining process that uses a plasma stream as the energy source. This welding method is successfully used for welding hard metals and alloys of tungsten, molybdenum, nickel, and stainless steel. Its application plasma welding  Found in instrument making and the aviation industry, it is characterized by deep metal penetration up to 9 mm thick in any space and position.

Plasma welding of metal: basic principles and differences

Plasma welding of metal, Depending on the magnitude of the plasma current, it can be:

• Microplasma, current value 0.1-25 A;
• At medium currents, the current strength is 50-150 A;
• High current, with a current value of more than 150 A.

Microplasma welding prevents burn-through of the metal. Therefore, it is used for joining thin metal up to 1.5 mm thick. The welding arc diameter is approximately 2 mm. This prevents heat from spreading across the entire metal surface, concentrating it at the desired point. It is ideal for producing thin-walled pipes and containers, welding traps and membranes to large parts, and joining foil.

Medium-current welding moderately penetrates the metal surface and fuses the parts together. The combustion principle is similar to argon-arc welding with a tungsten electrode. The weld width is narrow. Welding is performed with or without filler wire.

At high currents, welding completely penetrates the metal. The part is then cut and welded. This method is used to weld low-carbon and low-alloy steels. Non-ferrous metals such as copper, titanium, aluminum alloys, and titanium are also joined.

Also, depending on the selected current, different welds with different process qualities are produced. Therefore, the current supplied to the plasma torch is adjusted not only based on the metal thickness and type (non-ferrous metal, steel, cast iron, etc.), but also taking into account the process requirements established by GOST standards for the production of a specific part or structure. In everyday situations, current is selected based on the thickness of the metal parts or sheets, while process requirements are often determined "by eye," which may not always be the best solution. It's worth noting that even with relatively little experience using this equipment, a welder will already be able to determine the appropriate current for a given part, assembly, or metal.

Plasma welding of metal has its own types of flame combustion:

• Welding with a plasma arc, which burns between the product and a non-consumable electrode;
• A plasma jet burning between the plasma torch nozzle and a non-consumable electrode.

It's impossible to say definitively which type is better or worse, as each option has its advantages and disadvantages, although plasma jet welding is considered a more advanced solution. Plasma-forming gases can include oxygen, nitrogen, or compressed air. It's important to remember that the plasma temperature in any device (even a simple, inexpensive one) reaches 5,000–7,000 degrees Celsius, which is sufficient to cause significant harm to yourself or others with even minimal contact. Therefore, for safety, it's important to adhere to these basic, simple rules:

• Work only in special clothing (the fabric must be strong and dense enough, especially the front part);
• Do not start the installation if the work area is not yet prepared and the plasma torch is not in the hands of the welder or is not secured in the installation (may be relevant in production);
• Monitor the condition and quality of connecting hoses/cables;
• Not only the welder, but also the person assisting him must use protective equipment.

We hope this article was useful for you.