Laser welding sheet metal is an efficient and precise welding method that uses a high-energy density laser beam as a heat source. Laser welding is one of the important aspects in application of laser material processing technology. In 1970s, it was mainly used for welding thin-wall materials and low-speed welding. The welding process belongs to the heat conduction type, that is, the laser radiation heats the surface of the workpiece, and the surface heat diffuses to the inside through thermal conduction. By controlling the laser pulse width, energy, peak power and repetition frequency and other parameters, the workpiece is melted to form a specific molten pool. Due to its unique advantages, it has been successfully applied to the precision welding of micro and small parts.
Laser welding sheet metal can be achieved using continuous or pulsed laser beams. The principle of laser welding can be divided into heat conduction welding and laser deep welding. Power density less than 104 ~ 105W /c㎡ is heat conduction welding. At this time, the penetration is shallow and the welding speed is slow. When the power density is greater than 105 ~ 107W / c㎡, the metal surface is recessed into "holes" under the action of heat, forming deep penetration welding, which has the characteristics of fast welding speed and large aspect ratio.