Classification of plasma arc welding:

1. Small hole plasma arc welding

Small hole welding, also known as perforation, keyhole, or penetration welding. By utilizing the high energy density and strong plasma flow force of plasma arc, the workpiece is completely melted and a small hole is formed that runs through the workpiece. The molten metal interacts with arc suction, liquid metal gravity, and surface tension! Use it to maintain balance. When the welding gun advances, the small hole is locked behind the arc, forming a fully penetrated weld seam.

The perforation effect can only be formed under sufficient energy density conditions. Increase in plate thickness: The required energy density also increases. Due to certain limitations in the improvement of plasma arc energy density, small hole plasma arc welding can only be carried out within a limited plate thickness.

2. Penetration plasma arc welding
When the ion gas flow rate is small and the arc resistance to compression is weak, this type of plasma arc only melts the workpiece during the welding process without producing a small hole effect. The principle of weld formation is similar to tungsten hydrogen arc welding, which is also known as fusion or erosion plasma arc welding. Mainly used for single sided welding of thin plates, double sided forming, and multi-layer welding of thick plates.

3. Micro beam plasma arc welding
Fusion type plasma arc welding below 15-30A is commonly referred to as micro beam plasma arc welding. Due to the confinement effect of the nozzle and the simultaneous presence of arc current, low current plasma arc can be very stable and has become an effective method for welding thin metal foils. To ensure welding quality, precise welding fixtures should be used to ensure assembly quality and prevent welding deformation. The cleanliness of the workpiece surface should be given special attention. For easy observation, an optical amplification observation system can be used.
Microbeam ion
Microbeam ions are commonly used for welding thin plates (with a thickness of 0.1mm), welding wires, and mesh parts. A straight needle shaped arc can minimize the deviation and deformation of the arc. Although the equivalent TIG arc is more diffuse, the updated transistorized (TIG) power supply can generate very stable arcs at low currents.
Medium current
This method can be selected for traditional TIG welding in the melting mode. Its advantage is that it can generate deeper penetration (due to the high temperature plasma airflow) and allow for significant surface contamination, including the coating (electrode in the welding torch). The main drawback is that the welding torch is bulky, making manual welding more difficult. In mechanized welding, more attention should be paid to the maintenance of the welding torch to ensure stable performance.
Small pore type
The available advantages are: deep penetration and fast welding speed. Compared with TIG arc, it can weld through plates with a thickness of up to 10mm, but when using single pass welding technology, the plate thickness is usually limited to 6mm. The usual method is to use small holes with fillers to ensure a smooth (toothless) cross-section of the weld bead. Due to the thickness reaching 15mm, a 6mm thick blunt edge is required for V-joint preparation. Double pass welding technology can also be used to automatically generate the first and second weld passes by adding filler wire in the melting mode.
It is necessary to accurately balance welding parameters, plasma airflow speed, and the amount of filler wire added (filling small holes) to maintain the stability of the holes and welding pool. This technology is only applicable to mechanized welding. Although this technology can be used for positional welding by using pulse current, it is usually used for high-speed flat welding of thicker sheet materials (over 3mm). When welding pipelines, it is necessary to accurately control the overflow current and plasma airflow speed to ensure that the small holes are closed.