Laser Welding Defined

Laser technology and therefore laser welding has improved a lot during the past years. It has its extensive use in almost all the type of applications ranging from medical technology to welding technology. Laser has many advantages than conventional MIG or TIG welding. It has now become the preferred standard adopted by welding industry.

Laser is categorized by its type, peak power, beam size, beam quality, average power, characteristics, and pulse rate and output wavelength. Effect of a laser beam for laser welding different metals produces different result which makes it important to choose the correct laser quality for processes like cutting, marking, welding, scribing and engraving on metals.

The process of welding, scribing, engraving and cutting would require a category of laser known as CO2, whose power level ranges in between 10-watts and 25-kilowatts. A good reaction takes place with the CO2 laser with plastic, glass, fabrics, paper, wood and organic material. The wavelength of the CO2 laser is 10,600 nanometers. This high wavelength of CO2 laser makes it unfit for marking on metals for which only low power level is required. The power level of the latest CO2 lasers range from 10 watts to 500 watts and large percentage of this power is converted to heat which forces the use of a cooling mechanism. A laser make-up gas is the suitable coolant in laser welding to carryout the instant heat from the welding area.

Another type of laser used widely in industrial application is the Vanadate laser. The wavelength of this laser is 1,060 nanometers. Scribing and marking makes the best use of this kind of laser on materials like ceramics, soft metals and plastics. The output power of this laser ranges in between 5 watts and 100 watts. The "Q" switch is the distinctive unit of the vanadate laser.

In the diode pumped Nd: YAG lasers diodes and laser rods are used as their main laser building components. A good amount of heat generates from this kind of laser that needs better cooling attracts the use of water-cooling system. Water-cooling system works well and supports extended lifetime by regular changing of water filter, anti algae compound used in this system.

For laser welding microelectronic devices, the laser with short wavelength is best suited because of its small spot size; it can be focused to a small area to enable welding at very limited space constraint. For this purpose the "Q" switched vanadate lasers with frequencies 532nm, 355nm and 266nm are preferred option.

For laser welding applications like complex metal welding, drilling and cutting, the pulsed Nd: YAG laser is used. The wavelength of the laser for such process is 1,060 nm. If the power level of this laser is up to 50 watts then the pulse generated in 1 second is in between 1 and 25. For the highest power lasers the pulse rate in one-second ranges from 1 to 1000 pulses. A cooling system is needed at the higher power levels of these lasers. The maintenance cost of these lasers is very high compared to others.

Fiber laser is another kind of powerful laser having wavelength 1,060 nm. It supports two stage of power levels out of which the lower power levels are used for scribing and marking applications, whereas the high power levels are best suited for more complex jobs likes welding and metal cutting. The beam quality and efficiency of this laser is higher than any other type of laser having equivalent wavelength. It consumes less electrical energy than others, which make it a suitable option to be used in mobile welding units. It supports both air and water-cooling system. Except the maintenance of the cooling system used in this type of laser, other maintenance requirement of this type of laser and its related equipment are much lesser than its rivals.

The laser welding image above courtesy of Omega Thermo Products.