Laser Beam Welding is a technique practiced in manufacturing, where two or more pieces of material are joined by using a laser beam. Laser stands for Light Amplification by Stimulated Emission of Radiation. The process is totally non-contact that requires access to the weld zone from the side of the parts that are being welded. Laser beam welding is generally used to join the components that need to be joined with high speed. The features like high-speed welding, excellent automatic operations and the expectation to control the quality online during the process make the laser beam welding mostly preferred technique and a very common joining method in the modern industrial production.
The laser beam is nothing but a coherent light of a single wavelength. It has a very low beam divergence along with high energy content which automatically produces heat when it strikes a surface. Mostly used lasers in the welding are of the following type:
- Gas Lasers: These lasers use the mixture of various gases like helium and nitrogen. There are also CO2 lasers or popularly known as carbon dioxide lasers. These lasers use the combination of low-current, high-voltage power source to ignite and excite the gas mixture by using a laser medium. These lasers operate in a continuous mode. Carbon dioxide lasers use a mixture of carbon dioxide of high purity along with helium and nitrogen as the medium for lasing. In the laser welding called dual beam, CO2 lasers are used where the laser beam is split into two equal power beams.
- Solid States Laser: These are ruby lasers kind of lasers that work within the wavelengths of 1 micrometer, and can be pulsed or operated constantly. The joints produced by pulse operations are similar to spot welds but with complete penetration. The energy of the pulse is 1 to 100 joules, and pulse time is 1 to 10 milliseconds.
- Diode Lasers
Lasers are mainly used for the materials that are difficult to join through other methods, for hard to access areas and for extremely small components. Intert gas shielding is needed for more reactive metals.
There is a big difference between the laser beam welding and arc welding processes. Many factors affect the laser-wielding and the energy absorption by the material the major factors are the type of laser, the incident power density, and the base metals surface conditions. The laser does not require an electrical current also its output is not electrical in nature. Lasers are capable of interacting with any material. Neither does it require a vacuum nor does it produce x-rays.
The metals that use Laser welding are:
- Carbon Steel
- High strength low alloy steels
- Stainless steel
Following are the advantages of the Laser Welding:
- Easily works with high-alloy metals
- Can be used in an open air
- Transmits over long distance without any loss of power.
- Narrow heat affected zone
- Total thermal input is low
- Welds different metals together
- No necessity of filler metals
- Secondary finishing is not necessary
- Exact accuracy
- Produces deep and narrow welds
- Distortion level is low in welds
- High-quality welds
- Compatible to produce thin and small components too
- Zero contact with materials
- Some metals might crack due to rapid cooling rate
- The capital cost of equipment is high
- Maintenance costs are high
- Optical services of the laser are easily damaged
Laser soldering and brazing are the other two processes. In this, the laser beam melts the filler, which wets the joint without melting the base material. The processes became more popular in 1980’s to join the leads of electric boards. These are majorly practiced in the electrical industry.