Welding is a process by which two materials are joined together by being heated to their melting points allowed to coalesce forming a solid joint. Whereas other types of welding use flame or electrical arcs to produce the necessary heat, laser welding, also known as laser beam welding (LBW), produces this heat by the application of a highly concentrated beam of light. This is achieved through optical manipulation of the light by way of mirrors, lenses, and sometimes fiber optics.
The optically amplified and concentrated light focused on a particular area is converted to heat as it is absorbed by the surfaces to be welded. A highly concentrated light beam creates much more heat than the diffuse rays of the sun or ambient light and causes the material on which it is focused to heat up sufficiently to melt. Those surfaces that are to be bonded are then joined together in their molten states forming a solid bond between them as they cool and return to a solid state.
There are two types of lasers that are most common. They are gas lasers, such as carbon dioxide or helium-neon lasers, and solid state lasers, such as yttrium aluminum garnet (YAG) lasers. Each of these types of lasers produces a beam of specific wavelength that is not visible to the human eye but is easily absorbed by conductive materials.
Laser welding can be used to produce a number of different types of joints including tee and corner joints, butt joints, edge joints, and lap joints. Both gas and solid-state lasers can be used to weld continuously or in pulses. In addition to bonding things together, some laser welding systems may be used for other purposes such as cutting or drilling.
Laser welding may be applied to a wide range of material and component sizes. Due to the extremely focused nature of the beam, the welding area of the materials is minimal and therefore reduces the chance of damaging nearby components. Laser welding makes possible deep and narrow welds which sometimes cannot be achieved by any other welding technique. The speed of laser welding is relatively rapid compared to other types of welding, which can increase productivity and decrease costs in high-rate manufacturing facilities. Laser welding also allows for remote, automated operation such as computer-controlled laser welding in automobile assembly lines.
Some disadvantages that may need to be taken into account include the high capital cost of the equipment and the necessity of an extremely clean operating area in order to protect the optical components. Additionally, metals that are very reflective such as silver and gold are harder to weld using lasers because they deflect some of the light rather than absorb and convert it to heat. For applications that are well suited to laser welding, however, the savings generated by its use in large-scale production or its ability to uniquely achieve certain types of welds may outweigh the disadvantages.