Power density is one of the most critical parameters in laser processing. With a higher power density, the surface layer can be heated to the boiling point within a microsecond time range, resulting in a large amount of vaporization. Therefore, high power density is beneficial for material removal processing, such as drilling, cutting, and engraving. For lower power densities, it takes several milliseconds for the surface temperature to reach the boiling point. Before the surface layer vaporizes, the bottom layer reaches the melting point, and it is easy to form a good fusion weld. Therefore, in conductive laser welding, the power density ranges from 10 ^ 4 to 10 ^ 6W / CM ^ 2.
Laser pulse waveform is an important issue in laser welding sheet metal, especially for sheet welding. When the high-intensity laser beam hits the surface of the material, 60 ~ 98% of the laser energy will be reflected and lost on the metal surface, and the reflectivity changes with the surface temperature. During a laser pulse, the reflectivity of the metal varies greatly.
Pulse width is one of the important parameters of pulse laser welding sheet metal. It is not only an important parameter different from material removal and material melting, but also a key parameter that determines the cost and volume of processing equipment.