Welding with light

Laser-transmission welding rapidly joins thermoplastic parts without vibration or excess heat. By Val A. Kagan Robert Bray Welded assemblies made from fiberglass-filled and unfilled nylon 6 thermoplastic serve in a variety of automotive under-the-hood applications including intake manifolds, air inlets, and fluid reservoirs. Other potential applications include taillights, fuel line components, cell phone housings, and medical devices. The new Laser IRAM (Infrared Assembly Method) system from Branson Ultrasonics Corp., Danbury, Conn., illuminates the entire welding surface simultaneously compared to conventional systems that move the laser beam across the welding zone. The system welds plastics such as polycarbonate, acrylics, polystyrene, ABS, and elastomers. It can join like or dissimilar materials. Laser welders from Bielomatik Inc., Plymouth, Mich., steer beams from either CO2 or Nd:YAG lasers to the workpiece by moving the workpiece itself, moving the laser head with a robotic arm, or by redirecting the beam with two scanner mirrors, focusing optics, or wave guides. Welding-seam width is adjustable from about /10 mm to several millimeters. Automotive parts made from thermoplastics often weigh and cost less than equivalent metal castings and stampings. Typically, these assemblies are welded together by heat from friction, hot plates, or radiant heaters. Although these methods produce welds of