In-depth understanding of laser welding: working principle and application
In-depth understanding of laser welding: working principle and application.Laser welding is a process that uses a laser beam to join metals or thermoplastics together to form a weld. As such a concentrated heat source, laser welding can be performed at high welding speeds in meters per minute in thin materials.while in thicker materials narrow and deep welds can be produced between square-edged parts.
2 Modes of Laser Welding
The principle of laser welding can be divided into two fundamentally different modes of operation.They are heat conduction welding and laser deep penetration welding. The mode of interaction of the laser beam with the material it is welding will depend on the power density at which the beam hits the workpiece. When the power density is less than 104-105 W/cm2, it is heat conduction welding. At this time, the penetration depth is shallow and the welding speed is slow; aspect ratio.
Laser welding is usually done with a keyhole mechanism using higher power densities. When a laser beam is focused on a spot small enough, to produce a power density of typically >106-107 W/cm2, the material in the beam path not only melts but evaporates.A large amount of heat is then carried away by conduction. Focused laser beam It then penetrates the workpiece, creating a cavity known as the “keyhole”.It is filled with metal vapor. (which in some cases can even be ionized, forming a plasma).
The high-power-density laser is focused on the surface of the workpiece and evaporated to form a small hole. This hole absorbs all the incident light energy.The heat is transferred from the outer wall of the high-temperature cavity to melt the metal surrounding the cavity. The continuous evaporation of the material under the laser beam irradiation produces high-temperature steam.The surface tension of the wall layer formed by the liquid flow outside the hole wall is in balance with the continuously generated steam pressure in the hole cavity and maintains a dynamic balance.
The beam continuously enters the small hole, and the molten metal surrounding the hole wall moves forward with the leading beam.The molten metal fills the gap left by the small hole and condenses, thus forming a weld.
Applications of Laser Welding
Laser welding is mainly used in shipbuilding, automobile, aerospace, machinery manufacturing, and many other fields. For example, in the automobile industry, plate tailor welding can connect steel plates of different materials and thicknesses.Such way could reducing the weight of the car body and reducing material waste. In the aviation manufacturing industry, the fuselage of the aircraft is composed of many parts. Laser welding replaces the traditional rivet connection technology, which reduces the weight of the fuselage by 15%. In the shipbuilding industry, laser welding technology has the characteristics of high efficiency and large penetration depth.Such way could reduces the workload of dock welding and improves manufacturing accuracy.