A laser is a light source which emits light of a specific wavelength (single color) and all the waves are in 'phase'. Therefore, the light of a laser can be focussed to a much higher intensity then the light of a light bulb.
The best known example is the red laser pointer with a power of ≤ 1 mW (0.001 watts) that is often used as a pointer when making presentations. The red colour appears in the light spectrum visible to the human eye (approx 380 – 730 nanometres) at a frequency of 635 nm. It is possible to process material when lasers are used with higher power. Laser welding is one of the fastest rising applications of laser technology. Laser welding uses lasers with a power of about 6 kW (6000 watts). The lasers for laser cutting and laser welding processes usually work with the infra-red area of the colour spectrum which is invisible to the human eye. (1050 – 10600 nm).
How does it work?
Laser light is generated in a so-called ‘Resonator’ which contains a laser active medium. This medium can be solid material (crystalline material) or a gas.
- laser active medium
- Pump Energy
- Reflecting mirror
- Partial permeable mirror
- Laser beam
By introducing energy to the laser active medium (introducing so-called pump energy), the laser active molecule electrons rotate in a higher energy path. A photon is released when the electron falls back to its original, lower energy path. When the photon touches another electron, the process repeats itself and so we talk about a stimulated emission and a monochromatic beam is formed – the laser beam. Using different types of optics (lens sets), this laser beam can be focused onto a work piece for welding.
Gas - laser
Gas lasers were often used in laser welding in the past. CO2 (carbon dioxide) was activated by the addition of a number of other components. By adding energy by way of high frequency radio wave energy, a laser beam was created with a wavelength of 10600 nm (infra-red C long wave). This wavelength is absorbed by vitreous materials and therefore cannot be transported by glass fibre cables. The laser is transported by fixed carbon tubes through which highly conditioned air is blasted. This results in making connections to robots for 3D processing very difficult. These lasers were mainly used in so-called fixed scanner boxes above the product where welding occurs in the 2.5 D range.
CO2 lasers cause plasma (ionized air) when welding, which interferes with the laser beam or even completely absorbsall power resulting in bad welds or even no welding at all. This plasma must be blown off and lead away with a proper air treatment system in the welding cell.
Solid state - laser
Solid state lasers use a solid substance for generating the laser beam. A commonly used laser is based on a YAG (Yttrium Aluminium Garnet)crystal, which has a different shape depending on the actual type of laser (rod shaped, disk shaped, glass fibre).
By supplying the YAG crystal with laser active ions, a laser beam can be generated from the crystal. Much used laser active substances include Neodymium (Nd) which gives us the Nd: YAG laser, or Ytterbium (Yb) in the latest disk and fibre lasers. This gives us the Yb:YAG laser.
YAG lasers work in the infra-red A area (short wave) which is invisible to the human eye. Common wavelengths are 1050, 1064 and 1070 nm.
In comparison with CO2 lasers, the YAG crystal is pumped by way of Xenon flash lamps (old) or with laser diodes in the latest disk and fibre lasers (same as very powerful laser pointers). YAG laser light can be transported through glass fibres which allows laser welding to be combined with a robot. This makes 3D laser welding possible. Also with this type of laser there is air contamination formation that comes from the metal vapour / weld smoke around the welding position. Just as with the CO2 welding, the air surrounding the weld must be kept clean in order to obtain a good quality weld.
The latest generation of YAG lasers offer good quality laser beams (beam quality) so that laser welding can be done from a greater distance (600 mm+). Welding with a greater distance between the optics and the work piece is also called remote laser welding. In other words: laser welding from a (longer) distance.
The Laser cell FFO 2 is based on a double index table. The laser welding takes place at one position, while the welding parts are inserted and removed at the oth...
The Laser cell FFO 4 is constructed around a quadruple index table. The laser welding process takes place at one position. The other three positions are used for ...
The Laser cell FFO slide table is based on two slide units. These slides transport the welding jigs linearly in and out of the laser welding cells. Therefore, one jig i...
The Laser cell RSO 4 is based on a quadruple index table. The laser welding process takes place at the first position. The other three positions of the Laser cell ...
The compact Laser cell is the ideal solution combining high operator efficiency and low floor space. The Compact laser cell can be used for laser-weld...