Laser Welding

Welding is a method of joining two or more pieces of metal together using various techniques such as spot welding and arc-welding. Laser beam welding is another of these techniques and uses high powered lasers to join multiple pieces of metal together.

The use of a laser beam has many advantages such as narrow and deep welds due to its concentrated heat source. In the automotive industry laser beam welding is quite frequently used for it fast and high volume applications.

Laser beam welding allows high power density which results in localised heat affected zones and this then allows high heating and cooling rates. The size of the laser spot can be between 0.2mm and 13mm, however only the smaller sizes are used for welding applications.

The depth of penetration depends on the focal point of the laser and is proportional to the amount of power being supplied. If the focal point is just below the surface of the workpiece then penetration is maximised.

With laser welding a pulsed or continuous laser beam is used, and this will depend upon the application. To produce deep welds a continuous laser is used but on thinner materials such as very thin sheet metals a pulsed laser using pulses only milliseconds long are employed.

There are two types of lasers which are commonly in use and these are gas lasers and solid state lasers. The first type uses mixtures of gases such as nitrogen, helium and carbon dioxide as a medium, whilst solid state lasers use solid medias such as chromium in aluminium oxide, synthetic ruby, neodymium in glass, and the most common type used is crystal which is composed of yttrium aluminium garnet doped with neodymium. When the mediums of either type of laser is excited, they emit photons and form a laser beam.

With a gas laser the lasing medium is produced by using high voltage and low current power sources to excite the mixture, and these lasers can operate in both pulsed and continuous mode. The power requirements for gas lasers are generally much higher than solid state lasers, and can reach 25kW.

Solid state lasers have wavelengths much shorter than gas lasers, and operators need to protect their eyes with special goggles or specially designed screens to prevent damage to the retina within the eyes. To deliver the laser beam to the required weld area, fibre optics are usually employed.

Another type of laser is the fibre laser and the gain medium is the optical fibre itself. They are used for robotic industrial welding and are capable of up to 50kW.

Laser Welding can have many applications and is very widely used in the automotive industry.

If you are in need of this service check out our product pages, they contain many companies that specialise in this. John Cheesman writes about Laser Welding. Visit the Businessmagnet product page for details and suppliers of Laser Welding.

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