By Stéphane Melançon on May 05, 2023
Laser Welding
Fiber laser welding is a welding process that uses a laser beam as the heat source. As non-contact tools, fiber lasers are low maintenance and offer fast welding speeds. The laser beam is highly precise and has a low heat input, which minimizes damage to the material.
One of the emerging applications is to make cell-to-busbar connections for cylindrical and prismatic cells and modules. You can see an example in the following video:
To get a good understanding of the different possibilities, continue reading to discover all the essential information.
- Benefits & Challenges
- Fiber Laser Welding Systems
- Types of Fiber Laser Welding Systems
- Fiber Laser Welding vs. Other Welding Methods
- Laser Welding Applications
Benefits and Challenges
Fiber laser welding is becoming increasingly popular in manufacturing to scale up production and improve quality. But it also comes with its own set of challenges presented below.
| Benefits | Challenges |
|---|---|
| The welding speed is fast and can be scaled to each application by adjusting the laser power | Weld quality is affected by external factors (such as joint gap, material defects, etc.) |
| The process is precise and easy to control, making it highly repeatable | Laser safety measures are needed to protect workers and the work environment |
| Fiber lasers can weld a wide range of metals like copper, aluminum, stainless steel, and dissimilar metals | Variations in part positioning can affect the focus of the laser beam |
| Fiber laser technology is compact, minimizing floor space usage | The laser beam path must be unobstructed, including by dust and fumes (which can distort the beam) |
| The welding process is non-contact and requires little maintenance | The reflectivity of the material has a strong effect on the efficiency of the laser process |
| Lasers are operated by a controller, making them easy to automate with robots | Optical components require protection, so consumables like a cover glass are needed |
| Efficient use of the energy results in low heat input and causes minimal heat distortion | The laser process must be optimized for each application as each metal has different fusion temperature (this is especially challenging when welding dissimilar metals) |
Our laser experts know how to address these challenges and can help you.
Fiber Laser Welding Systems
A fiber laser welding system with the laser source, laser controller, and laser welding head. Image property of Laserax.
Optical & Electrical Components
Fiber laser welding uses a highly focused laser beam to join metals. The laser beam is generated through a system of electrical and optical components. Below is a list of the most important ones and their definitions.
- Power supply – The power supply converts electrical current into direct current (DC) to be used by the pump source.
- Laser source – The laser source includes the pump source, the gain medium, and the laser cavity. The pump source is an electrical device (typically an array of laser diodes) that converts electrical energy into laser light. The gain medium is a fiber doped with a rare-earth element (like ytterbium). When pump light goes through the doped fiber, excited molecules generate light of a specific wavelength. That light is amplified in the laser cavity.
- Fiber optics cable – The fiber optics cable is used to guide laser light and deliver it to the right location on the processed surface.
- Fiber collimator – The collimator is a lens that transforms the light coming out of the fiber optics cable, converging it into a single direction to better focus its energy.
- Beam expender – The beam expender increases the size of the collimated laser beam. While the beam is less concentrated this way, the laser process tolerates surface and positioning variations better.
- Scanning head – The scanning head contains rotating galvo mirrors that control the direction of the laser beam.
- Focusing lens – The focusing lens is used to focus the laser beam on the processed surface. For example, a 200 mm focusing lens provides a good focus to weld at a distance of 200 mm.
- Focus shifter – Also called 3D head, the focus shifter is an optical assembly that can adjust the focal distance on the fly to account for large surface or positioning variations.
Other Components
Fiber laser welding machines include other components besides optical and electrical ones. Here’s a few that are common.
Wire feeder
A wire feeder can be used to add filler material during welding. This is a hybrid technology between MIG welding and laser welding. Wire feeding can help achieve high weld quality in certain cases, but it slows down the welding process, as the laser’s energy is used to melt more metal. Wire feeding is useful when the joint fit-up is not perfect and causes gaps; when solidification is too fast and causes cracks; and when you need to modify the mechanical properties of the weld.
Shield gas
To prevent oxidation of the welds, some manufacturers use a shield gas (like argon) in combination with laser welding. While using a shield gas is not always needed to achieve the required weld quality, it is always beneficial, as it helps reduce the number of defects in the welds. A good practice we use at Laserax is to develop the laser welding process without a shield gas and aim to achieve a good welding quality this way. If shield gas is added afterwards, it will only benefit the process.
Laser controller
The controller is an electronic device that controls the laser process by adjusting parameters like the laser power, pulse repetition rate, and pulse duration. It is also used to control safety features.
Fume extraction unit
Laser welding generates toxic fumes and contaminants that need to be extracted and filtered from the work environment. We have tips on how to perform fume extraction to maximize its efficiency and ensure safety.
Laser weld monitor
Different LWM methods exist to provide a real time analysis of the welding process. Laser weld monitoring (LWM) is essential to ensure a good weld quality and detect any deviations from good weld characteristics. It is used to define when welds need to be reworked (pass/fail).
Chiller
High-power lasers used for industrial welding generate heat that needs to be managed to maintain an optimal operating temperature and prevent safety issues. Depending on the laser power, different cooling systems can be used, such as an air chiller or a water chiller.
Continuous vs. Pulsed
Continuous and pulsed fiber lasers can both be used for laser welding. Their characteristics make them better suited for different applications. Here’s how they differ:
- Price: Continuous-wave lasers are less expensive
- Weld size: Continuous-wave lasers can produce larger welds more easily
- Heat-affected zone: Pulsed lasers have a lower heat affected zone
- Welding depth: Pulsed lasers can generate shallower, less intrusive welds
Single mode vs. Multimode
Single mode lasers are better for micro welding applications that demand increased precision like battery tab welding, while multimode lasers are ideal for larger workpieces that need to be processed faster. Here are their key differences.
- Precision: With their smaller spot size, single mode lasers offer increased precision for micro welding applications. Multimode lasers are less precise, as the laser beam is less focused.
- Energy density: Single mode lasers generate laser beams with a higher energy density due to the smaller beam size and better beam quality. While multimode lasers have a lower energy density, they can process larger surfaces faster.
- Heat-affected zone: Single mode lasers have a lower heat affected zone since heat is used more efficiently. Multimode lasers tend to generate lower quality welds with higher porosity.
Types of Fiber Laser Welding Systems
Handheld Laser Welding Machines
Handheld fiber laser welding machines are more accessible than ever. Similar to MIG and TIG welding systems, operators hold a “gun” to trigger and direct the laser beam. Even new, inexperienced welders can become productive quickly and create high-quality welds, as the learning curve is much lower.
Laser Welding Workstations
Workstations are semi-automated solutions that typically require an operator to load workpieces and launch the laser welding process. They are ideal to run small production batches, support product development, and develop a process optimized for a specific application. You can see an example of this with our laser welding workstation for battery manufacturers.
Robot Laser Welding Machines
Robot arms are frequently used in laser welding due to their precision and repeatability. Robot arms can be programmed to move the laser welding head to specific points on the workpiece, allowing it to weld large workpieces like car body parts, airplane wings and pipes.
Robot-Assisted Laser Welding Machines
In production lines, robot arms can be used to move and position clamping tools during laser welding, minimizing the amount of wait time for clamping. This also makes it possible to adapt the clamping positioning and pressure for each individual weld.
Our battery laser welding machine is a robot-assisted solution designed to help manufacturers scale up production and improve quality. Its automation and vision features allow it to weld at high speed. For 21700 cylindrical cells, our machine averages 100 ms/cell.
Fiber Laser Welding vs. Other Welding Methods
Fiber laser welding is increasingly used in today's production lines because of its many benefits over traditional welding methods. It offers higher precision and speed, better weld quality, and the ability to weld a wider range of materials.
The process is also environmentally friendly, reduces waste, and requires less maintenance than other welding methods. This makes it a cost-effective and sustainable solution for modern manufacturing.
Laser vs. Ultrasonic Bonding
Ultrasonic bonding is a method that uses ultrasonic vibrations to join surfaces together. You can find more information on how the method works here. Here are key differences between ultrasonic bonding and laser welding:
- Lasers are much faster. In EV battery production lines, they are at least 10 times faster than ultrasonic bonding, allowing manufacturers to scale up production and reduce the number of machines on the shop floor.
- Lasers produce stronger and more durable bonds.
- Lasers provide greater precision and control over the welding process, resulting in a higher quality weld.
- Ultrasonic bonding cannot be used to weld thick parts (usually limited to a few millimeters)
- Ultrasonic bonding can be used to weld plastics and malleable metals. Lasers can be used for a wider range of metals as well as to join dissimilar metals.
- Ultrasonic bonding requires a lower initial investment.
Laser vs. MIG Welding
MIG welding, or Gas Metal Arc Welding (GMAW), involves the use of a wire electrode that is consumed during the welding process to produce an electric arc and heat the metal being joined.
Fiber laser welding produces higher-quality welds than MIG welding, especially for applications that demand high precision and control. It is also a better solution for manufacturers looking to scale up production.
However, laser welding is more expensive and complex to set up.
Laser vs. TIG Welding
TIG welding, also known as Gas Tungsten Arc Welding (GTAW), uses a non-consumable tungsten electrode to create an electric arc and melt the metal being welded. A separate filler rod is used to add material to the weld joint as needed.
Unlike fiber laser welding, TIG welding requires a highly skilled welder to control the heat input and filler metal. The process is also slower and more labor-intensive.
Laser welding produces a smaller heat-affected zone, causing less damage to the material. However, TIG welding may be preferred for applications where appearance is important, as it produces more aesthetically pleasing welds.
Laser vs. Resistance Welding
Resistance welding passes an electric current through the metal parts being welded. As current goes through the metal, electrical resistance at the point of contact generates heat and causes the two metals in contact to melt. Electrodes can be used to create a spot weld, or rotating wheels can be used to create a seam weld.
Fiber laser welding generates better welding results than resistance welding. As a non-contact process, it produces very small and precise welds with minimal heat input, resulting in minimal distortion and a smaller heat-affected zone.
Resistance welding is harder to control due to the electrodes wearing off. It is more suitable, however, for small manual operations, since lasers come at a high initial cost.
Laser Welding Applications
With almost limitless laser configurations, laser welding technology is versatile and adaptable. This makes it effective in a range of industries, allowing for high-quality welds of both small and large workpieces.
| Industry | Examples of Applications |
|---|---|
| Automotive | Battery cells & modules, body in white, suspension system, transmission system |
| Aircraft | Turbine blades, frames, fuselage sections |
| Electronics | Printed circuit boards, battery cells & modules, housings, electrical contacts |
| Medical | Medical devices and implants |
| Construction | Window frames, plates, pipes |
| Defense | Frames, armor plates |
The Growing Role of Fiber Laser Welding
As the demand for faster, more efficient, and more precise manufacturing processes continues to grow, fiber laser welding is likely to play an increasingly important role in many industries.
If you have a welding project that can benefit from a laser, contact our laser experts today.
