From home hobbyist to large manufacturing operations, the art of welding has been in use since 3000 B.C. Yet over these many centuries, how we weld two pieces of metal together has changed. With an increase in knowledge and access to technology, there are now over 30 different welding types used today. One such technique available is laser welding.
What is Laser Welding?
As the name implies, laser welding employs a machine that focuses a beam of light along two metal pieces to join them together. Depending on the size of the workstation, the machine can be freestanding with the laser source mounted or can be a handheld collimator. The beam of light is concentrated at a single point where it generates heat to melt the two metals so that they will fuse together when cooling. In other instances, a filler may be used but is not typically a requirement.
Types of Lasers and Welding Methods
Laser welding is a broad category that is narrowed down to the types of methods, techniques, and machines used to form the welded joint. There are about 13 different laser machines and welding methods. Here are the most common ones that are used today.
Laser Types
- Solid-State Laser Welding: Solid-state laser welding uses glass or gems, called gain medium, and a laser diode to emit light in a specific wavelength to produce the laser beam. Yttrium aluminum garnet (YAG), disk lasers, and newer fiber lasers are types of solid-state lasers.
- CO2 Welding: Carbon dioxide (CO2) laser welding uses nitrogen, carbon dioxide, and helium as the machine excites the gas molecules. The molecules then emit radiation that becomes focused to form a laser beam.
Laser Welding Methods
- Heat Conduction Welding: Heat conduction welding is used when melting thin materials and fitted edges as it uses a lower power to melt the materials.
- Laser Spot Welding: Laser spot welding is a technique where located spots are welded or when one material is melted all the way through to connect to another material. It is used for small parts.
- Laser Seam Welding: Laser seam welding creates a long continuous weld. It is often used with a filler rod.
- Deep Penetration Welding: Deep penetration welding cuts a deep and wide keyhole through a thick piece of material that becomes filled with molten filler.
There are several factors used when deciding on which type of laser and method to use on materials. The types of materials, thickness of the materials, the weld length, the amount of power available, and the application are several important considerations. You also must consider between automated and handheld methods as well as production output requirements when selecting the appropriate laser equipment.
Materials Used in Laser Welding
An important factor when selecting materials to weld together is the material’s reflectivity. The laser beam can become deflected by highly reflective materials, causing the beam to be diverted from the surface. Tungsten and die-cast zinc cannot be welded using lasers. Materials that also have low thermal conductivity are also difficult to laser weld.
Materials Used in Laser Welding
- copper
- aluminum
- titanium
- steel
- nickel
- nylon plastic
- polycarbonate plastic
- carbon-reinforced plastics
- ceramics
Difference Between Laser Welding and Other Welding Modalities
When talking about traditional welding modalities, the three that come to mind are resistance spot welding, metal inert gas (MIG), and tungsten inert gas (TIG). The popularity with these traditional methods remains strong, as laser welding is still trying to gain a solid foothold. There are some key differences when comparing these methods.
Traditional methods work by using arcs (plasma or gas) or a flame with continuously fed wire. The feed wire helps to reinforce the welds. However, while laser welding can use filler rod, it often forms intricate welds without filler. The quality of laser welds is equivalent to traditional welding methods while speeding up the process. The laser beam’s concentrated point melts the materials extremely quickly as the heat pool doesn’t spread very far.
Laser welding also has the ability to weld dissimilar materials. This factor increases the number of materials that can be used. You can obtain high quality welds quickly.
Traditional welding methods are cheaper than laser welding. These initial costs may dissuade many companies from making the switch. However, operational costs between the two are the same, making laser welding a good option for companies that are looking for automated welding options or precision welding methods.
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