⑴ penetrating type (small hole type) Plasma arc welding: Using the characteristics of small plasma arc diameter, high temperature, large energy density and strong penetrating force, under the appropriate technological parameters (larger welding current 100a~500a), the weldment will be fully penetrated, and under the action of the plasma flow, a small hole through which the welding parts are formed. and the plasma arc welding method of some plasma arc is sprayed from the back of the welding piece. Double sided welding can be used to weld $number mm stainless steel, 12 mm below titanium alloy, $number mm low carbon steel or low-alloy structural steel and copper, brass, nickel and nickel alloy butt welding. (The plate is too thick, by the plasma arc energy density limit, the formation of small holes difficult; the plate is too thin, small holes can not be completely closed by liquid metal, solid can not realize small hole welding method. ）

⑵ penetration type (dissolved type) plasma arc welding: The use of small welding current (30a~100a) and low plasma gas flow, the use of hybrid plasma arc welding method. does not form small hole effect. It is mainly used in welding of thin plate (0.5 ~ 2.5 mm) and welding of welding and fillet weld of each layer after multilayer welding.

⑶ Micro-beam plasma arc: welding current under 30A plasma arc welding. The nozzle diameter is very small (φ0.5~φ1.5 mm), and the needle-like tiny plasma arc is obtained. It is mainly used for welding the ultra-thin, ultra small and precise welding parts under 1 mm.