Laser Beam Welding:
Laser beam welding is a welding process that uses a laser beam to melt and vaporizes a material. LASER (Light Amplification by Stimulated Emission of Radiation) beams are very high energy density electromagnetic beams which are highly coherent, monochromic and unidirectional.
Power of LASER:
For example, a LASER can give a power output of nearly 100 W/mm2 of beam cross section in short bursts. By focussing this beam on a spot (1 / 100) mm2 in size, the beam will be concentrated to a power density of 10 KW / mm2. This concentrated energy is so intense that it easily ionizes the atmospheric air to create sparks. With the beam focused from a high power laser, even the hardest material like “diamond can be melted in a fraction of a second. Temperatures of the order of 8000 deg Celsius have been produced in less than 0.5 milliseconds with lasers. This high energy can be used to melt and vaporize work piece material in a very short time and permit its fusion with another metal.
In addition to welding, LASER’s can be used for cutting, drilling, micromachining, surface heat treating and selective cladding of materials.
1. Automotive industry
a. Gear parts such as Cog wheels, planet gears
b. Body making such as bottom plates, skins etc.
c. Engine components such as tapper housings, diesel engine pre-combustion chambers
2. Aerospace industry
a. Engine components
b. Instrument cases
3. Steel industry
a. Pipe production
b. Vehicle superstructures
c. Continuous metal strips
4. Electronics industry
b. Accumulator cases
c. Transformer plates
d. Cathode ray tubes
5. Plant and Apparatus engineering
a. Seal welds at housings
b. Measurement probes
6. Medical industry
a. Heart pacemaker cases
b. Artificial hip joints
Advantages of laser beam welding:
1. The laser beam can melt and vaporize any known material. Even non-metallic and refractory materials can be easily worked with.
2. It can easily weld or join dissimilar metals or metals which are difficult to weld by conventional methods
3. No flux are filler metals is needed
4. The ability to focus the beam at very narrow spots makes welding of extremely small components and deep welding possible
5. Heat affected zone is small. This is helpful in welding close to heat sensitive areas
6. Production rates are fairly high
7. The process can be easily automated
8. Welds can be made inside transparent glass or plastic housings
9. Areas not readily accessible can also be welded
10. Can cut holes as small as .005 mm with depth/diameter ratios of 50:1
Disadvantages of laser beam welding:
1. Cost of equipment is high
2. High reflectivity materials are difficult to work with.
3. Laser welding is limited to depths of approximately 1.5 mm and additional energy only tends to create gas voids and undercuts in the work
4. Materials such as magnesium tend to vaporize and produce severe surface voids.
5. Deep cut produce taper