Advances in manufacturing technology and the trends for more precise part geometry have opened the door for new metal-joining applications where traditional TIG and resistance welding methods no longer meet precision, quality, or productivity requirements. Pulsed laser spot welding technology is now being used to replace these processes, often with increased productivity and lower overall cost.

Moreover, the demand for greater precision in high-performance assemblies has favored the use of these lasers as a more cost-effective alternative to the resistance welding that has been used for decades. Fiber laser spot welding eliminates problems associated with resistance welding, including electrode sticking, and cleaning or replacement. Also, since laser welding is a non-contact process, there is no metal deformation of the component parts.

Spot welding is the simplest form of laser welding. There are two types of spot-welding modes: conduction and penetration. The conduction welding mode is employed for micro-joining purposes. Penetration welding permits aspect ratios (ratio of depth to width) much higher than unity.

Lasers are capable of delivering ac ontinue or a pulse of laserlight with accurate, repeatable energy and duration. When the beam is focused into one place - a small spot - (adjustable anywhere from approximately 0.1 to 50.0 mm in diameter) on the part, the energy density becomes quite large. The light is absorbed by the material causing a "keyhole effect" as the focused beam drills into, vaporizes, and melts some of the metal. As the pulse ends, the liquefied metal around the keyhole flows back in, solidifying and creating a small spot weld. This entire process just a few milliseconds.

Lasers can fire many pulses per second, and, by moving either the work piece or optics, allow either separate "spot" welds or a series of overlapping spot welds to create a laser seam weld that can be structurally sound and/or hermetic.