Nowadays, the laser welding technique is quickly applied to production lines in all walks of life, with laser marking, engraving, cutting, and welding as the main application processes. In addition, laser repair and laser cleaning are also used in a small number of specific scenarios.
For a long time, experts have recognized the excellent market potential of laser welding techniques. However, the market application has not developed well due to insufficient laser power, inadequate workpiece fixtures, and a high barrier to research and development in automatic control.
In the past, most laser welding techniques used traditional YAG and CO2 lasers. With traditional laser welding stand-alone equipment, the technical threshold is not high. This low-power welding machine is limited to simple welding tasks for specific industries, such as molds, glasses, jewelry, and advertising channel letter making. As a result, it has a narrow application range.
Development of laser welding technique
Fiber laser welding expands the range of materials and applications that can be welded. Innovations in laser technology and beam delivery devices address the challenges that laser welding has faced. This includes improving the ability to weld copper, dissimilar materials, thin metal foils, and poorly assembled parts.
Fiber lasers offer an increasing choice of beam characteristics, wavelengths, output powers, and pulse durations. Combined with advanced oscillation welding technology, fiber lasers have significantly reduced past application challenges. These advancements include improved coupling to highly reflective materials and enhanced solidification behavior of the melt pool. They also involve eliminating defects, better control of penetration depth, and compensation for poorly assembled parts.
Additionally, integrated full-process monitoring technologies, such as coherent imaging, enable real-time information collection during the welding process. This helps manufacturers maintain tight control over weld quality and improves productivity. Together, these driving technologies facilitate the rapid adoption of defect-free laser welding technology in advanced applications across various industries.
Standard welding heads are designed to focus a collimated laser beam to the desired spot size and keep the beam path static during beam delivery, presenting a static spot in the focal plane. This standard configuration results in each setup being limited to being geared toward a specific application. In contrast, the oscillating weld head incorporates scanning oscillator technology within the standard weld head. Moving the beam with an internal mirror makes the focal spot no longer static. You can dynamically adjust it by changing the shape, amplitude, and frequency of the various patterns. Additionally, the beam speed \( V_c \) can be controlled using the oscillation frequency \( f \) and the oscillation diameter \( D \), following the equation \( V_c = \pi D f \).
The benefits of this oscillation welding method are more apparent when more minor spots are used. When using near-infrared (NIR) wavelengths, the smaller spot size achieves a high power density. This effectively overcomes the high reflectivity of materials such as copper and aluminum. This results in stable keyholes with a wide processing window and avoids porosity and cracking when using optimal oscillation parameters. This development opens up new applications for 1µm fiber lasers in electric vehicle and battery manufacturing. It eliminates the need for frequency-doubled green lasers.
In the past two years, handheld laser welders have achieved good shipments because the price of a set of laser welding equipment has dropped significantly to at least about 10,000 US dollars, while a set of traditional low-power argon arc welding is cheap at 500 US dollars and expensive up to $2000.
In addition, laser welding is fast and produces high-quality welding surfaces with excellent sealing performance. These advantages have made it the preferred choice for many hardware processing applications. However, hand-held laser welding still relies on manual labor, and no automation exists.
In the future, apart from a few extra-large parts, structural parts with high added value, such as rail locomotives and aerospace parts, will require customized welding. Most other mass-produced industries, such as batteries, communication devices, watches, consumer electronics components, etc., need automated laser welding production lines.
Power batteries promote the development
About eight years ago, the world began vigorously promoting the development of new energy vehicles, mainly electric vehicles. These vehicles can reduce automobile exhaust pollution caused by oil use, promote automobile replacement, and promote the consumption economy.
Sales of new energy vehicles have grown significantly over the past five or six years, and many automakers have joined the ranks to launch electric cars. The country’s long-term goal is to make new energy vehicles account for nearly one-third of annual sales. The core technology of electric vehicles is, of course, batteries. The significant demand for power batteries has led to the rise of several lithium battery companies.
Power batteries bring a lot of demand for laser processing. The manufacturing process needs laser cutting, and more laser welding is used. Connecting sheets, cells, copper materials, aluminum alloys, battery packaging, etc., are all laser welding. The laser equipment for power batteries is a highly automated production line workstation with certain thresholds. Power batteries have brought breakthroughs to the demand for laser welding, driving more than 2.5 billion in demand for welding equipment in 2020.
Electric vehicles, in particular, are the primary driver of this trend. The automotive industry and suppliers are looking for robust, efficient welding processes for the high-volume production of copper and aluminum joints, which are in wide demand in electric vehicle (EV) batteries and power storage products.
Another problem in copper welding is instability, as the molten metal’s low viscosity and surface tension can lead to spatter and porosity when welding at low speeds. Increasing the speed to over 10m/min minimizes these instabilities and creates a stable welding process. However, this means that the best welding parameters are within the limits of conventional motion systems, such as robots. In addition, the depth of melt decreases with increasing speed, and the weld seam becomes very narrow. Increasing the laser power has to compensate for this, which requires a higher capital investment in the system.
New process studies show that the above phenomena can be avoided and that the welding process can be stabilized by increasing the welding speed and dynamic positioning of the laser technology, e.g., with an oscillating welding head, to achieve a stable weld. This oscillation technique allows stable welding at low linear welding speeds with minimal effect on the melt depth. For example, high-quality copper welds up to 1.5 mm deep can be achieved with only one 1 kW single-mode fiber laser.
The same technology is available for high-brightness multimode lasers and has been used extensively to improve weld quality and weld consistency in aluminum housings. The gradient of temperature and cooling rate change is slower than conventional laser welding, which helps to eliminate defects and suppress spatter generation.
A comparison of welding 5000 series aluminum housings with standard welding technology and oscillating welding technology, using the same 3.0kW power, shows that oscillating welding results in a more consistent, porosity-free weld. With a weld depth of 5mm, it is clear that the oscillating welding technique is superior in terms of overall weld quality.
In Conclusion: the laser welding technique
Power batteries are only one area of laser welding applications. In the future, we predict that more industrial processes will use laser welding techniques, and the process will be batched when it matures. Laser welding often requires reliable parts and stability of welding quality. Varibend has been committed to making products that customers can trust for more than ten years. Contact our Gold Service team to learn more.
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FAQs
1. What industries benefit most from laser welding?
Laser welding is widely used in automotive, aerospace, electronics, and telecommunications industries due to its precision, speed, and adaptability to different materials.
2. Can laser welding handle dissimilar materials?
Yes, modern laser welding technologies, such as fiber lasers, are capable of welding dissimilar materials, including metals with different melting points.
3. How does oscillation welding improve weld quality?
Oscillation welding improves weld quality by distributing heat more evenly, reducing defects like porosity, cracking, and spatter.
4. Is laser welding faster than traditional methods?
Yes, laser welding is generally faster than traditional methods and provides higher precision with less post-processing required.
5. Are handheld laser welders practical for small businesses?
Absolutely! Handheld laser welders are cost-effective and easy to use, making them ideal for small-scale operations or specialized tasks.
