Laser welding is a technology that has applications in a wide variety of industries. It is chosen for its ability to generate high-quality welds at high speed. It is also chosen for precision welds that do no cause damage to delicate components.
In this article, I will share with you how manufacturers use laser welding to reach their goals through six applications. I will also compare laser welding to traditional methods like TIG, MIG, and arc welding to demonstrate how it is different.
Table of Contents
- Laser Welding Applications
- Can Laser Welding Join Dissimilar Metals?
- What is the Penetration Depth of Laser Welding?
- What is the Heat Affected Zone of Laser Welding?
- Does Laser Welding Cause Porosity?
- What Type of Laser to Use for Welding?
Laser Welding Applications
1. Hairpin Welding (Electric Motors)
In the manufacturing of electric motor stators, hairpin windings made of copper are joined by laser welding. Precise control of the heat input provides uniform low resistance in the welds, ensuring good and consistent electrical conductivity.
Laser welding is ideal for this application, as hairpins are relatively small and require a precise process that does not affect surrounding components. Prior to welding, methods like laser cleaning and mechanical stripping are used to precisely strip the protective coating from the connection points, ensuring clean welds with no contaminants.
2. Battery Welding (EVs & ESSs)
With the strong shift towards electrification, batteries used in electric vehicles (EV) and energy storage systems (ESS) increasingly rely on laser welding to keep up with fast-paced and high-quality production requirements. These connections were traditionally made with slower technologies like ultrasonic bonding or resistance welding. You can learn about the difference between laser and ultrasonic welding here.
Laserax offers turnkey laser welding solutions for battery production as well as welding services for manufacturers developing their products. We also provide laser welding speeds we can achieve for battery applications.
3. Structural Welding (Body-in-White & Fuselage)
Laser welding is used for a wide range of structural welds, including body-in-white components in the automotive industry and fuselage sections in the aerospace industry. Combined with the dexterity of robot automation, laser welding offers the flexibility required to join complex shapes.
4. Turbine Repair
Laser welding is used to repair turbine blades that have suffered from harsh operating conditions that have led to cracks, erosion, and other forms of damage. The process restores the turbines to their original structural integrity and functionality.
The laser beam melts and fuses material in the damaged areas to repair them. This is done using either a filler material or by re-melting the base material.
5. Welding Medical Devices
In the medical industry, laser welding is used for complex applications that require high precision and the ability to adapt to complex geometries. Examples of applications include the hermetical sealing of titanium shells enclosing medical implants, or the sealing of components in pumps, cylinders, and containers. Inert gases like argon are typically used to prevent oxidation and the contamination of the weld area.
6. Welding Jewelry
Portable and handheld laser welding devices are used in the jewelry industry to create custom designs, incorporate stones, and perform repair work. Laser welding offers the precision needed to accomplish precision work, and its low heat input minimizes the risk of thermal damage.
Can Laser Welding Join Dissimilar Metals?
Laser welding can join dissimilar metals (without the need for filler material), but there are important limitations that need to be discussed.
First of all, regardless of the welding method, you cannot fuse different metals into a homogeneous melting pool. When the molten metals mix, they create a heterogeneous mixture where the molten metals remain separate.
With laser welding however, the different metals melt and resolidify in a few milliseconds. This rapid solidification prevents the metals from separating into different layers, a common issue in other welding methods with slower cooling.
You can see the result of the quick solidification in the picture below, where two different metals are mixed but still visibly separate.
Such joints are not as strong as those of similar metals, but they are strong enough for many applications where electrical conductivity is more important than strength, as is the case with EV batteries and electronic connectors for example.
What is the Penetration Depth of Laser Welding?
The penetration depth depends on the laser welding method. Conduction welding is a softer type of laser welding that only joins materials at the surface. Keyhole welding is a more aggressive type of welding that penetrates deep into the material.
In production lines, keyhole welding is typically used because it’s much faster and can keep up with short cycle times. At Laserax, we use it to make battery connections. We control the welding process to achieve a specific depth (typically between 100 µm and 500 µm) depending on the thickness of the cells and busbars.
Compared to traditional welding methods, laser welding provides a much better depth of penetration. This is because the heat input is better controlled and focused. For this reason, laser welding can quickly dig into the material (within a few milliseconds).
What is the Heat Affected Zone of Laser Welding?
The heat affected zone (HAZ) is lower with laser welding because of the high control over the heat input. This helps maintain better mechanical properties as well as minimize heat distortion and part warping. There are also minimal heat effects on surrounding components and materials.
Laser welding has a minimal HAZ because everything is in place to make sure there is no excess heat:
- The laser beam is controlled with just the right energy amount for welding.
- The laser beam is programmed to move at a precise speed to ensure optimized energy deposition in the weld seam.
- The laser beam is focused on a small spot size, making it possible to weld small areas with minimal heating of surrounding ones.
Does Laser Welding Cause Porosity?
Due to how it works, laser welding causes less porosity than traditional welding methods. But before I explain why, it’s important to understand why porosity happens.
All welding methods have the potential to create porosity in the welded joints, where air penetrates the part to form tiny holes or voids. Porosity happens because as the metal melts during welding, gases such as oxygen, nitrogen, and hydrogen can become trapped in the molten metal.
When the molten metal solidifies, these gases are unable to escape, resulting in the formation of tiny pockets or voids within the weld.
Porosity is a serious issue that can lead to the internal oxidation of the metal and compromise its structural integrity.
During laser welding, the metal melts and resolidifies within a few milliseconds. This leaves almost no time for gases to penetrate the welds and cause porosity. Other methods have a lower control over the heat input and create a molten pool that lasts much longer, increasing the likelihood of gas entrapment and porosity.
What Type of Laser to Use for Welding?
A wide range of lasers can be used for welding and will prove successful. These include fiber lasers, CO2 lasers, Nd:YAG lasers, blue lasers, green lasers, and diode lasers. You can learn more about the different types of lasers here.
In industrial settings, we recommend fiber lasers for several reasons:
- They are within the most robust lasers on the market, with a proven record of operating 24/7 for +10 years with minimal maintenance and consistent quality.
- They have low operating costs due to their high energy efficiency.
- They are easier to automate due to their optical fiber beam delivery, making them easy to integrate with robots or CNCs.
- They can have high laser powers without compromising quality or precision.
Need Laser Welding for Batteries?
I hope this article helped you see the potential of laser welding and discover its wide range of applications. With its many benefits over other technologies, manufacturers and researchers are exploring new applications all the time.
If you need to laser weld batteries, we have laser welding solutions for you. Don’t hesitate and contact our team at Laserax to discuss your application and requirements.