Laser welding, occurs when the laser is used as an intense energy surce to selectively heat materials to a point between their melting and vaporizing temperatures. Once molten, the materials are allowed to alloy and then resolidify in a controlled atmosphere. The result is reliable, oxide-free weldment. The overall size and depth-to-width ratio of the weld can be custom tuned depending on materials and laser source selected. By adjusting various parameters such as the laser energy and focal point position, one can create weld ratio ranging from wide and shallow to narrow and deep. In most cases the welded part geometry dictates this ratio.

Laser welding offers a variety of benefits over other types of welding: deep penetration of precise narrow welds, small heat affected zone, low heat input, fast weld times, minimum part distortion, no secondary processing and high repeatability. Many metals can be welded including stainless steel, carbon steel, titanium, aluminum and dissimilar metals.

When defining a weld joint we refer to both the joint type and the weld type. There are two joint types: butt and lap. A butt joint is where two materials are to be welded at the seam that forms where the two materials are joined together. A lap joint is where two materials are to be joined by welding through one into the other. There are also two weld types: seam and spot. Seam welding is continuous while spot welding is intermittent. Glass sealing and glass-to-metal sealing is also accomplished with Nd:YAG lasers. Plastic welding with Nd:YAG lasers has been in development for some time and is now commercially viable with certain plastics.