By Stéphane Melançon on February 14, 2023
Laser Welding
Laser spot welding is a welding process that uses the power of a laser beam to join two metal surfaces at a single spot. The laser beam targets a small spot and transfers enough energy to melt and fuse metal surfaces together. It is fast, precise, and can weld various metals, including dissimilar metals.
Laser seam welding is when surfaces are welded over a long, continuous surface. But when spots are welded close to one another, laser spot welding starts to look like laser seam welding.
In this article, you’ll find out what you can do with laser spot and seam welding, how different methods work, what are the best laser welding systems, and how laser welding is making its way in EV battery production lines.
What is Laser Spot Welding?
Laser welding can be used to create spot welds. These welds look similar to the ones generated by resistance welding (also known as resistance spot welding).
Resistance Welding vs. Laser Spot Welding
Like laser spot welding, resistance spot welding joins surfaces at a single point. The difference is that resistance welding uses electrodes to apply pressure on the surfaces to be joined. An electrical current is also passed through the electrodes to weld the surfaces. With laser spot welding, no electrodes are needed; welding is done using a laser beam.
Laser Spot Welding Methods
Different laser spot welding methods exist. Keyhole spot welding creates small but deep welds. Deeper welds are preferred to provide more strength to structural welds. Conduction spot welding creates larger but shallower welds. Shallower welds are preferred if heat-sensitive materials must not be damaged during welding.
What is Laser Seam Welding?
Laser welding can be used to create seam welds, which is when surfaces are joined over a long, continuous seam. Seam welds are stronger, can produce leak-proof seals, and tend to increase the strength and durability of products.
It’s natural to think that continuous seams are done using continuous beams, which is when the laser beam is continuously released during welding. But contrary to expectations, laser seam welding can be done using both pulsed lasers and continuous lasers.
Pulsed Lasers vs. Continuous Lasers for Laser Seam Welding
Pulsed lasers can release laser pulses and generate a series of spots that overlap. The small overlap between each spot can be so small—just a few microns—that the weld looks like a seam.
Pulsed lasers minimize heat affected zones, avoid thermal damage to the workpiece, control the heat input, prevent warping, allow for higher welding speeds, and improve weld quality and repeatability.
Continuous lasers generate a seam weld without spots. They provide consistent heat input for a uniform welding process, reduce the need for multiple passes (or multiple seams), allow for high power welding of thicker materials, and are generally cheaper than pulsed lasers.
Laser Spot & Seam Welding: Are They Non-Contact Processes?
Laser welding systems are sometimes presented as non-contact tools, but this is misleading. While it’s true that the laser performs welding from a distance without physically touching the part, the components that are joined must be held together during the welding process. This is mandatory to obtain good, consistent welds with zero gap.
But the tools used to hold parts together and close the gap add mechanical movements, which may slow down the welding process.
Laserax has developed a laser welding machine that makes use of robot arms to apply pressure on the areas to be welded. The robot arms minimize the downtime caused by mechanical movements and, as a result, maximize the laser’s uptime. You can watch the following video for a demonstration of the process applied for busbar laser welding in battery manufacturing.
Moving Away from Resistance Welding
While resistance welding is used for small projects, laser welding is better adapted to high-volume, industrial applications. Resistance welding may be cheaper, but its high temperature input can damage components, especially the ones that are heat sensitive.
Nowadays, this is especially important in EV battery production lines, where battery cells must be treated with precision and minimal heat input.
The electrodes used during resistance welding can apply an inadequate welding force. If the welding force is too low, you get weak connections and low-quality welds. If too much welding force applied, the electrodes cause the deformation of the workpiece and create a weld with a contact surface that’s way too large.
These problems are easier to manage with laser welding, which offers advanced control of the process parameters. At Laserax, we use highly precise robots to apply pressure on the welds, making sure that the right welding force is applied.
Advantages of Fiber Laser Welding
Laser welding is a fast, industrial process. This is especially true when using fiber laser welding systems. Fiber lasers offer a range of advantages over other laser technologies like Nd:YAG lasers and CO2 lasers, such as:
- Increased precision for high quality results
- Smaller footprint
- Better electrical efficiency
- Lower maintenance
- Lower operating costs
- High speed processing
Laser Welding Application in EV Battery Manufacturing
With the rapid rise of the EV industry, automotive manufacturers and their suppliers are increasingly using laser welding in their production lines. Our lasers are currently used in high-volume battery production lines. For laser welding, we offer several options, including continuous-wave fiber lasers with up to 2000W of laser power.
If you want more information on how you can use laser welding for battery manufacturing, contact one of our laser experts.
