What is Laser Beam Welding? (And How Does It Work?)

What is Laser Beam Welding?
Definition: Laser welding (or laser beam welding) is a fusion welding process in which the joining of metals takes place due to heat produced by a laser beam.

In Laser beam welding, the laser acts as a concentrated heat source and it is focused on the weld region which melts the metal and welding takes place.

Deep, narrow welds with a high welding rate can be achieved by using a laser welding process.

By the way, if you don’t know the full form of LASER, then here it is;

LASER: Light Amplification by Stimulated Emissions of Radiation

Laser welding process (How does laser welding work?)

what is laser welding
Image credits: the welding master

The setup for the laser beam welding process is shown in the diagram above.

The laser welding diagram consists of following components;

  • Ruby crystal
  • Electrical power source
  • 100% reflecting mirror
  • Partially reflecting mirror
  • Flash lamps
  • Focusing lens

The laser beam used for laser welding can be generated by using either gas laser, liquid state laser or solid state laser.

Above diagram shows the solid state laser.

As shown in the schematic diagram, the ruby crystal is used to generate the light source.

The ruby crystal is surrounded by flash lamps. When the electric power is supplied, a high amount of light source is produced.

Now, the upper part of the ruby crystal is covered by the fully reflecting mirror. So all the light is reflected back.

The other mirror which is towards the down side is a partially reflecting mirror.

Because of the fully reflecting mirror (upper side) and partially reflecting mirror (downward side), the high density of the photon beam is generated (see the arrows in the image).

This high density photon beam (or laser beam) passes towards the focusing lens.

Because of the focusing lens, the laser beam is concentrated at the point on the weld surface.

laser beam welding process
Image credit: Research gate

This concentrated laser beam produces a very high amount of heat which can melt the metal surface easily.

The filler material (or filler wire) is used to fill the weld groove during the laser welding process.

In this way, the metal pieces are welded by using a laser beam welding process.

I hope you have understood how laser welding works. Now let’s see few more important things about laser welding.

Properties of laser beam in laser welding

The laser beam obtained in the laser welding process shows various properties as mentioned below.

  • The laser light is monochromatic in nature, that means it has a single wavelength.
  • Laser beam is intense and very powerful.
  • Laser light is highly collimated, that means it could travel a very long distance without any deviation.

Because of these properties of lasers, it is used in welding of various similar and dissimilar metals in industries.

How laser welding differs from electron beam welding?

Here is a difference between laser welding and electron beam welding.

Laser welding Electron beam welding
1). In laser welding, the photons are focused on the workpiece.1). In electron beam welding, the electrons are focused on the workpiece.
2). The laser beam have more tendency to diverge when it comes in contact with the workpiece surface.2). The tendency of electron beam to diverge during the contact with the workpiece surface is very less. So it gives deeper holes with less distortion.
3). In laser welding process, the inert gas is used as a shielding gas.3). Vacuum chamber is used in electron beam welding process to prevent the atmospheric contaminations.

Advantages of laser welding

Advantages of laser beam welding process are mentioned below.

  • By using laser welding, the similar and dissimilar metal can be welded.
  • High precision welding of parts which are difficult to reach can also be welded using a laser welding.
  • Heat affected zone is minimum. So the laser welding can be used for welding the locations which are surrounded by heat sensitive components.
  • The weld joints obtained by this process are clean.

Disadvantages of laser welding

Disadvantages of laser beam welding process are mentioned below.

  • Welding speed is slow.
  • Equipment cost is higher.
  • Rapid cooling of weld joints may develop cracks (especially in high carbon steels).

Applications of laser welding

Applications of laser beam welding process are mentioned below.

  • Laser welding is used in electronics industries to connect wires to electronic components.
  • It is also used to weld medical equipment (as medical equipment needs to be clean).
  • Used in automobile industries to weld transmission components.

External links:
Laser beam welding: Image credits Krorc, CC BY-SA 3.0, via Wikimedia Commons

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