Nd:YAG lasers are available with optics that are two or three generations ahead of current machines, says Lee R. Gilbert, president and CEO of the Pawrucket, R.I.-based United States Microscopic Welding Association. For instance, an open model Class IV mobile unit comes with a microscope perched on the end of a long arm. Users can position the arm as required to weld workpieces of almost any size. In contrast, most laser welders only handle workpieces the size of a grapefruit or smaller. The mobile unit also melts wire from 0.005 to 0.040-in. diameter without the porosity typical of laser welding with large-diameter wire.

A small, enclosed, Class I model is used for repairing small to medium molds and dies, and the production welding of medical devices made from exotic metals such as beryllium, titanium, aluminum, and copper. Some applications require fusion welding. This melts the parts at the joint and does not require use of filler wire.