Laser Beam Welding: Definition, working, Application, Advantages and Disadvantages

Laser Beam Welding (LBW)

Definition of Laser Beam Welding:

The laser beam is a beam of light, coherent and strictly monochromatic. The intense power of the beam (with a small cross-sectional area) enables welding to be performed over small areas (Laser is abbreviated for light amplification by stimulated emission of Radiation)

Working principle: 

Laser has its different forms such as ruby laser, gas laser, liquid laser, semiconductor laser. These names are based on how the laser is obtained. Ruby for ruby laser, a mixture of helium and neon for gas laser, nitrobenzene for liquid laser and gallium arsenide for semi-conductor laser is the materials used.

 

Working principle of Laser beam welding

Fig shows ruby laser, its working principle is explained as it can be applicable to all laser welding. A pumping unit is providing the energy to the laser medium in this process, which energized its atoms so that they can enter into high potential zones. To acquire stability these atoms return back by emitting light. Their absorbed energy is converted into light and they return back into low energy zones. Such radiation is called stimulated emission.

These light waves strike with other excited atoms causing continuous amplification of light. The medium is so surrounded by reflective surfaces, hence a continuous increase in it is resulting. The total energy so produced is then passed a small hole of glass and in the form of a laser beam.

This narrow ray is focused by an optical focusing lens and allowed to fall on the job as a laser pointer. By doing so the optical energy gets transformed into heat energy so that the increased temperature becomes sufficient to melt the component. A cooling system is also required in this process as most of the energy is converted into heat energy. The pumping unit for ruby laser includes flash lamp & medium ruby (Solid-state)

Advantages and disadvantages of Laser Beam Welding:

Advantages:

1. Welding can be done in transparent glass and plastic housing.
2. Almost all metals can be welded.
3. The electrode is not used hence the effects of high current and defects caused by electrode are not observed.
4. The area which is not easily approachable can also be welded.
5. Welding can be done in micron by this process & small parts can also be welded.
6. The heat is produced for short duration & on small area gives good quality weld without much altering the structure of the metal. In other words, we can say that the heat-affected zone is small.
7. It is possible to weld in an open atmosphere.
8. The light is used for welding can be focused on microscopic dimension to obtain higher accuracy.

Disadvantages:

1. The process is slow.
2. It has limited use up to 1.5 mm thickness.
3. Vaporization and porosity are developed in weld metals like magnetism.
4. The maintenance cost of LBM is high.
5. To perform LBW high skilled labour is required.

Applications:

1.    To join metals having a high melting point and higher hardness.

2.    For micro-welding.

3.    For welding copper, nickel, aluminium, stainless steel, tungsten, zirconium, tantalum etc.

4.    To join parts of dissimilar metals.

5.    In space and aircraft industries.

6.    Laser beam equipment can also be used for metal cutting.

7.    To join tiny electronics parts and to produce integrated circuit (IC).

           

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