Laser welding has been in use for more than 30 years, but until recently, it was used selectively. Thanks to modern CNC methods, however, it is now being used much more
widely to produce parts and products for a variety of manufacturing industries.
Like all welding processes, heat is exerted at specific points to create a lasting bond, but with laser welding, less heat is generated. Compared to conventional processes, the result is less distortion, greater precision and higher quality results.
Unlike the laser welding machines of the past, computers manage and operate today’s machines, feeding them instructions, which alleviates the need for manual procedures. With such a highly automated process – from the design of parts in CAD programs to the completion of making the parts – laser welding machines provide users with a host of advantages. To better understand these machines and why they are advantageous to modern manufacturers, a refresher course on the technology can be helpful for those considering it.
Process basics
In the context of laser welding sheet metal parts, the basic process is fairly straightforward: Two sheets of metal that have been precisely cut are held together when a laser beam is directed at the joint of the parts’ metal edges. The melt flows into each piece until the joint is complete.
A temperature just above melting point is required to be able to weld materials together, which means the melting temperatures of specific materials can be limited in traditional welding processes. This, however, is not the case for laser welding as it provides the greatest flexibility in terms of welding temperatures. Although higher temperatures can be achieved during laser welding, the following melting points are listed for materials that can be processed by laser welding:
- Steel: 1,400 degrees C
- Copper: 1,085 degrees C
- Glass: 600 to 800 degrees C
- Aluminum: 600 degrees C
- Plastics: 150 to 350 degrees C
Because of the concentration of heat produced by the laser’s small beam size, both thick and thin materials can be joined without significant heat distortion, if any at all. This means that most post-processing requirements are eliminated. For those accustomed to the heat-affected zones created during traditional welding processes, such as TIG and MIG, grinding and finishing operations are commonplace. This is not the case with laser welding.
Modern laser welding machines also make it possible to weld shapes that are complex in nature, including welding in multiple axes. Because the tool head moves along the required path practically contact-free and the transfer to the workpiece occurs through the air, the guide and bearing of the robot arm are barely exposed to any significant wear.
Finally, as is the case with fiber laser cutting machines compared to CO2 laser cutting machines, maintenance and consumable costs are minimal. It is possible, however, to add gases and wire feed if and when the process requires it. No matter the application, laser welding machines are built to last as long as users do not purchase second-rate machinery.
Laser welding advantages
Precision and low heat input are two of the most outstanding properties of laser welding machines, but another benefit is the working speed of the machines. Under ideal conditions, users can weld a long and straight endless seam at a speed of 60 m/min. That means even thick sheets of metal can be accurately joined within seconds. So, it is no wonder that more and more manufacturers are using laser welding.
The combination of high speeds and low-temperature inputs also provide users with minimal invasiveness. Complete heating of the base material is not required, so selective
thermal expansion does not occur. That means users avoid distortion of the part after cooling, again reducing the need to perform finishing operations on the welded component.
Laser welding’s uniform pulsed beam is also in play in terms of achieving a particularly clean seam. With conventional welding processes, welding beads or burrs can occur, but that is avoided with laser welding.
As mentioned, one of the biggest benefits of laser welding is the various types of materials that can be welded using laser welding machinery. The ability to weld dissimilar materials is also an attractive benefit. Unlike conventional welding processes, laser welding can be applied to sheets of greater thickness. Because of laser welding’s variable temperatures, the welding process is relatively insensitive to individual types of metals. So, whether welding copper, stainless steel or structural steel, laser welding is masterful at completing welding tasks with consistent accuracy.
When it comes to welding aluminum, only an aluminum-manganese alloy is able to be welded without requiring filler material. Every other alloy can be laser welded with the assistance of additives. That particularly applies to aluminum-silicon compounds.
Overall, the main advantages of laser welding include:
- High joining speed
- High precision
- Consistent quality
- Wide material tolerance
- No burr formations or heat distortion, leading to a reduction or elimination of post-processing requirements
The only prerequisites are having a sufficiently narrow welding gap and precisely set welding frequency and temperature. Even if the joining gap is too large, users can still achieve a satisfactory result by using deposition or fill welding.
Target industries
Today, laser welding machines are being used more and more widely in a variety of industries. Some of the industries that use laser welding the most are automotive, medical, aerospace and electronics.
In the automobile industry, laser welding has become popular due to its tool-free mode of operation as well as the ability to easily automate the process for mass production. Due to the strength of laser welded parts, they are ideal for various uses in the automotive industry, such as parts used in powertrain systems. Recently, laser welding has seen even greater adoption among automotive manufacturers due to the need to weld dissimilar materials in electronic vehicle battery production.
Additional industries are also finding favor in laser welding due to the fast processing of thick sheets with high tolerances. That, in fact, is one of the reasons laser welding is now being widely used in the shipbuilding industry to make parts like rudders and drive screws.
With its fast production times and high-quality results, laser welding is becoming a popular choice for a wide variety of applications. As machine costs become more affordable, it will undoubtedly continue its march toward widespread use.
