One of the most technologically sophisticated types of welding is laser (Light Amplification by Stimulated Emission of Radiation) welding. Its uses are widespread and include anything from aerospace to the creation of exquisite jewellery.
However, several welding techniques were in use before laser welding, so why do we need laser technology when there are other options?
After quickly reviewing the development of the technology, we will move into that. The fundamental tenet of a laser, stimulated emission, was predicted by Einstein.
However, it wasn’t until 1967 that we employed laser for the first time to do welding and cutting using a laser welding machine. The laser utilised in the 1967 tests combined a focused CO2 laser beam with oxygen-assisted gas.
Dr Peter Houldcroft served as the project’s main proponent. A B J Sullivan and P T Houldcroft’s publication, Gas-jet laser cutting, described the experiment in detail.
As laser cutting involves melting the metal without really cutting through it, it served as the inspiration for laser welding.
The laser welding procedure
For the region under the laser beam to absorb the light and become extremely energetic, laser welding employs a highly focused beam of light on a very small point.
The material melts as a result of the atoms’ breaking of their connections with one another as strong laser beams are employed to excite the electrons in the region.
Plastics may be joined using laser welding as well.
The two materials melt together at their seams, joining them together. It is amazing how strong light can be to melt metal within milliseconds. The laser welding equipment employs several elements that guide and amplify the laser to produce such strong laser beams.
The three types of lasers most frequently used in laser welding equipment are gas lasers, solid-state lasers, and fibre lasers.
Typically, optical fibres are used to provide the laser beam to the laser welding equipment. There are machines for welding single fibres and machinery for welding numerous fibres. Each fibre in the multiple fibre welding equipments is coupled to a laser, and as the strength of the laser grows, so does the fibre count.
A collimator lens and a focusing lens are frequently used together to focus the beam before it exits the machine.
Laser welds are capable of four primary weld joints:
- Butt Weld
- Filler Lap Weld
- Overlap Weld
- Edge Flange Weld
processing gas used in laser welding
If you have been researching laser welding, you may have observed that the process gas or cutting gas supply nozzle is always present alongside the laser nozzle.
To prevent contact between the weld surface and the environment, a flow of gas, most frequently CO2, is also directed towards the weld spot.
There are only two alternatives for welding an atmosphere without the use of cutting gas: either a normal atmosphere or a vacuum. Although laser welding in a vacuum is technically feasible, it is not practical due to the high cost and need for specialized equipment.
Without a processing gas, laser welding might have negative results in a typical environment. Due to the extremely high concentration of nitrogen in the air, mixing it with the molten metal might result in the creation of gaps or holes inside the weld.
Weld failures may result from such situations.
When welding, factors like air humidity might lead to hydrogen generation. Weak weld joints are another effect of hydrogen diffusing into the metal. Therefore, laser welding in a typical environment without shielding is not even considered.
The cutting gas attachment that is included with welding equipment ensures that no contaminants are combined with the weld by shooting gas onto the weld surface.
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