LASER BEAM WELDING
What is laser beam welding?
Laser beam welding (LBW) refers to a welding technique that is used for joining metal pieces or thermoplastics with the help of a laser. The laser beam generates a concentrated source of heat that helps in forming deep, narrow welds with high welding rates.
Laser beam welding is commonly used in the automotive industry for several high volume applications using automation. It is primarily based on penetration or keyhole mode welding.
How does a laser beam welding machine operate?
Laser beam welding machine comes with a high power density having the order of 1 MW/cm2. As a result of this, LBW forms small heat-affected zones with very high cooling and heating rates. The laser spot size usually ranges from 0.2 mm to 13 mm. For welding purposes, generally smaller sizes are preferred. The penetration-depth during welding is directly proportional to the power supplied. The location of the focal point also plays a role in determining the depth of penetration: penetration is maximum when the focal point lies beneath the sample surface.
The laser beam used may be continuous or pulsed depending upon the application of the welding system. For welding thin materials like razor blades the use of millisecond-long pulses are preferred. For deep surface welding continuous laser systems are generally used. LBW is a multipurpose technique that is able to weld materials like carbon steels, stainless steel, titanium, HSLA steels, and aluminium.
What are the advantages of laser beam welding (LBW) over electron beam welding (EBW)?
- Electron beam welding (EBW) requires a complete vacuum for operating. Creating a total vacuum might be difficult so using laser beam welding (LBW) is preferred (which works in the air also).
- The laser beam welding (LBW) process can be easily automated with the help of robotic machinery.
- X-Rays cannot be generated in the laser beam welding (LBW) process.
- Laser beam welding (LBW) provides better quality welding compared to electron beam welding (EBW).
What are the equipments required for laser beam welding?
Lasers (light amplification by stimulated emission of radiation):
Generally, for laser beam welding (LBW) solid-state lasers like ruby lasers and Nd:YAG lasers and gas lasers are used.
Solid-state lasers produce laser beams having wavelengths in the range of 1 micrometer. Nd: YAG lasers can be made to work in two different modes: pulsed and continuous. Nd:YAG lasers play an important role in a number of manufacturing purposes like etching, engraving, metal surface enhancement, marking metals and plastics, and welding and cutting steel or alloys or semiconductors. Nd:YAG lasers are crucial for conducting several processes such as etching, metal surface enhancement, engraving, marking metals and plastics, and cutting/welding steel or semiconductors.
Gas lasers incorporate the use of low-current and high-voltage power sources for supplying the required energy to excite the gas mixture (helium or neon or carbon dioxide) as a lasing medium. Carbon dioxide or CO2 lasers are capable of providing high-power continual laser beams. This is why it is used for welding and cutting materials like alloys, metal, or glass. Carbon dioxide or CO2 laser’s output wavelength depends on the type of isotope present in the CO2 molecule. For The heavier isotopes, the output wavelength is longer.
Nowadays, Optical fiber-based lasers that provide high power continual laser beams are considered to be effective for several industrial applications like welding (especially robotic industrial welding) and cutting materials like polymer or metal or glass. Optical fiber-based lasers are comparatively more compact than solid-state or gas lasers (of the same power output) and generate a diffraction-limited, high-quality laser beam.
Automation and Computer aided manufacturing (CAM):
Initially, laser beam welding was carried out by hand without computer intervention. But nowadays, with several developed technologies laser beam welding is aided by computers. Computer aided manufacturing (CAM) involves a programmed set-up of lasers that works automatically. This has improved the manufacturing quality and has allowed mass application in lower costs.
What is remote laser beam welding?
Traditionally, in the laser beam welding machines the laser outputs followed the seam with the help of robots usually. However in recent times, remote beam welding has become more popular. In this technique the laser beam moves along the seam with the assistance of a laser scanner. This method does not require a robotic arm following the seam. Remote laser welding provides a more precise welding at a greater speed.