LASER BEAM WELDING
In this process, fusion is achieved by directing a highly concentrated beam to a fine spot. The word LASER is an abbreviation of Light Amplification by Stimulated Emission of Radiation. High energy output is available from CO2 Laser and Nd-YAG Lasers. In CO2 Lasers, CO2 is the lasing medium. A high voltage of the order of 20 to 30 KV is applied through a pair of electrodes. This high voltage excites the gas particles. When a fundamental particle of light such as
photon hits the excited gas CO2 gas atom, the excited CO2 gas atom returns to normalcy. But, in the process it emits another photon with same direction, amplitude and frequency. This achieves the light amplification by stimulated emission of radiation.
The emitted photons travelling in the same direction, hits the mirror in one direction, reflected back & hits the mirror in the opposite direction. Within a short time, a narrow, coherent beam of laser light is formed, a part of which comes out through the partially transparent output mirror. This beam is further focused to achieve the welding or cutting, etc. Depending on the lasing medium, we have solid, liquid, gas and semiconductor lasers. CO2 Laser is the most popular gas laser and Nd-YAG is the most popular solid laser used for industrial applications. Laser beam can be used to weld otherwise difficult to weld metals such as nickel, tungsten steel, titanium and columbium. This can also be used for cutting hula rubber, plastic, paper, cloth, etc. Lasers are used in medical, electronic, automobile, sheet metal
works, aerospace, defence, communication and fabrication industries.