Laser welding is a technique for joining thermoplastic sheets, films or molded parts using the heating power of laser beams to melt plastic at the interfaces. First demonstrated in the 1970s, laser welding was for many years too expensive to compete with older plastics joining techniques such as vibration and hot-plate welding. Since the mid-1990s, however, laser welding has grown in popularity as the costs of the required equipment have declined.
Laser welding systems are most useful when the parts being joined are delicate (electronic components), or require sterile conditions (medical devices and food packaging). The relatively high speed of laser welding makes it valuable on assembly lines for plastic automotive parts. Laser welding can also join parts with complex geometries that would be hard to link with other welding methods.
The most common form of laser welding is called transmission laser welding. In this process, two plastic parts are clamped together and a laser beam, in the short-wavelength infrared (IR) region, is directed at the section to be joined.