Laser welding is a process that uses the radiant energy of a laser to achieve effective welding. Its working principle is to excite a laser active medium (such as a mixed gas of CO2 and other gases, YAG yttrium aluminum garnet crystal, etc.) by a specific method. The reciprocating oscillation in the cavity forms a stimulated radiation beam. When the beam is in contact with the workpiece, its energy is absorbed by the workpiece, and welding can be performed when the temperature reaches the melting point of the material.
Laser welding can be divided into thermal conduction and deep penetration welding, the heat diffusion to the interior of the former workpiece by heat transfer, melting phenomenon is generated only at the weld surface, the interior of the workpiece without full penetration, substantially no vaporization, are used for low-speed thin-walled The welding of the material; the latter not only completely penetrates the material, but also vaporizes the material to form a large amount of plasma。 Due to the large heat, a keyhole phenomenon occurs at the front end of the molten pool。 Deep-fusion welding can thoroughly penetrate the workpiece, and has high input energy and fast welding speed。 It is the most widely used laser welding mode。
Advantages of laser welding
1 Laser welding can achieve high quality joint strength and large aspect ratio, and the welding speed is faster.
2 Because laser welding does not require a vacuum environment, remote control and automated production can be achieved through lenses and optical fibers.
3 Laser has a large power density, good welding effect on difficult-to-weld materials such as titanium, quartz, etc。, and can weld different performance materials。
4 Micro soldering is possible. The laser beam is focused to obtain a small spot, and can be accurately positioned, and can be applied to the mass welding of small and small workpieces that are automatically produced in large quantities.
Disadvantages of laser welding
1 Laser and welding system parts are more expensive, so the initial investment and maintenance costs are higher than traditional welding processes, and the economic benefits are poor。
2 Due to the low absorption rate of the laser by solid materials, especially after the plasma appears (the plasma has an absorption effect on the laser), the conversion efficiency of laser welding is generally low (usually 5% to 30%).
3 Due to the small focus spot of laser welding, the precision of the equipment for the workpiece joint is high, and the small equipment deviation will cause large machining error。
Is laser welding harmful to people?
The invisibility and energy of the laser emitted by the welding machine is too high, and non-professionals should not touch the laser source, otherwise it is dangerous. In addition, the laser is also an electromagnetic wave, but the laser used in the welding machine has a large wavelength, so there is no radiation hazard of short-wavelength light waves such as ultraviolet rays.
Many gases are produced during the welding process, but most of them are inert gases。 They are not toxic, but they should also be treated differently depending on the welding materials。 It is best to take protective measures to reduce gas inhalation。
The laser emitted by the welding machine has almost no radiation hazard, but there will be ionizing radiation and stimulated radiation during the welding process, preferably away from the welding site during the welding process. This kind of induced radiation is not short-lived, and it has a great influence on the eyes and the body. It is better to stay away from the solder joints. For close-up work, try to take protective measures such as wearing respiratory protective gear, wearing radiation protective clothing, and eye mask.
(This article was originally written by Chenxi Laser. Reprinted must indicate the source: www.levihersh.com, cherish the labor results of others, is to respect yourself)