Laser Welding Unveiled: Advantages, Applications, And Industry Insights

By John Oncea, Editor

Laser precision allows for better quality welds, faster throughput, reduced post-processing costs, and access to new domains of application. So, bring on, right? Well ...

Have you ever used a magnifying glass to focus sunlight on an object?

If so, what you were doing was using the curved (or “convex”) surface of the magnifying glass to redirect sunlight into a small dot. That light is made up of photons and, when concentrated on a tinder such as a newspaper for 20 seconds or so, creates heat which in turn creates fire.

In simple terms, that is what laser welding is. However, in reality, laser welding is more complex than just starting fires with a magnifying glass. It is a fusion process that utilizes a highly concentrated beam of light to melt and join materials – typically metals or certain thermoplastics. The focused laser energy quickly heats a very small area, creating a melt pool that fuses the parts as it cools. Because the energy is so localized, the process produces very narrow welds with minimal heat-affected zones, which helps reduce distortion and maintain material properties.

A Brief History Of Laser Welding

The history of laser welding, according to Laserax, traces its roots to 1960 when Ted Maiman successfully built and fired the first laser. Maiman’s laser was a solid-state pink ruby laser, a type also used for the first uses of laser welding. The ruby laser was followed by gas lasers like the carbon dioxide (CO2) laser, which offered greater power and efficiency.

Laser development continued during the 1960s and 1970s and it was during this time the lasers’ capability to melt and fuse metals – thereby offering an alternative to traditional welding methods such as MIG, TIG, and arc welding – was expanded upon. Some of the advances made during this time include:

• 1962: Researchers at the American Optical Company use an Nd:Glass laser to weld steel and titanium.
• 1963: Elias Snitzer demonstrates the first fiber laser, but it is limited in terms of output and efficiency compared to other lasers.
• 1964: Bell Laboratories researchers invent the Nd:YAG laser, which provides more power and efficiency than Nd:Glass lasers.
• 1967: Researchers demonstrate the practical applications and viability of laser welding at the Battelle Memorial Institute, paving the way for further development and widespread adoption.
• 1967: Peter Houldcroft of TWI (The Welding Institute) used an oxygen-assisted CO2 laser beam to cut through a sheet of steel 1 mm thick, marking the first commercial application of laser materials processing.

In 1970, at the Western Electric Company, CO2 lasers were used for laser welding for the first time, Laserax writes. They provided more power and lower costs than solid-state lasers like Nd:YAG lasers. Fiber lasers that provided higher beam quality and efficiency, lower maintenance, and easier integration were introduced at Southampton University in the U.K. in the 1980s, and during the 1990s laser systems began to be integrated with robotic arms for automated welding processes.

Continued advancements in fiber laser technology during the 2000s made laser welding affordable for a wider range of manufacturers and, during the same decade, advancements in scan heads paved the way for remote welding, making it possible to precisely direct laser beams from afar.

Finally, in the 2010s remote laser welding systems became increasingly feasible and commercially available, enabling the delivery of laser energy to the workpiece through fiber-optic cables over longer distances. Today, laser welding technology continues to evolve in a wide range of aspects, including in terms of laser power, optical components, beam quality, scanning heads, and computer control systems.

Recent advancements in laser welding technology have led to more efficient and versatile laser welders, Oxygen Service Company writes. Key developments include the creation of fiber lasers and disk lasers, which provide unmatched energy efficiency and beam quality.

Additionally, the use of CNC machining and automation has integrated laser welding into large-scale manufacturing systems. Today's laser welders feature advanced capabilities like real-time weld monitoring and automatic parameter adjustment, which improve weld quality and throughput.

How Laser Welding Works

“Laser welding is a process used to join together metals or thermoplastics using a laser beam to form a weld,” writes TWI. “Being such a concentrated heat source, in thin materials laser welding can be carried out at high welding speeds of meters per minute, and in thicker materials can produce narrow, deep welds between square-edged parts.”

Laser welding operates in two primary modes – conduction-limited welding and keyhole welding – depending on the power density across the beam impacting the workpiece. In conduction-limited welding, where the power density is typically less than 10⁵ W/cm², the laser energy is absorbed only at the material’s surface, preventing deeper penetration and resulting in a weld with a high width-to-depth ratio.

More commonly, laser welding uses higher power densities via a keyhole mechanism. When the laser beam is focused to a sufficiently small spot to generate power densities greater than 10⁶–10⁷ W/cm², the material in its path melts and vaporizes before significant heat can be conducted away. This creates a cavity – known as a keyhole – filled with metal vapor (which may even become ionized to form a plasma).

The expanding vapor or plasma helps prevent the molten walls from collapsing into the keyhole, dramatically improving the laser’s coupling to the workpiece. Deep penetration welding is then achieved by traversing the keyhole along the joint, producing welds with a high depth-to-width ratio. As the weld progresses, surface tension drives some molten material from the leading edge around the cavity to the back, where it cools and solidifies, leaving a weld cap with a chevron pattern that points back toward the start.

Why Choose Laser Welding?

Laser welding has emerged as the preferred technology for metal fabricators and manufacturers, finding applications in automotive, medical device production, aerospace, and precision electronics, writes Gentec EO. The reason for this is the many advantages it offers, including minimal thermal impact on surrounding surfaces.

“Welding, both traditional and laser-based, implies heat delivery at the junction between two surfaces. The melted metals mix and, after they’ve cooled, form a strong bond, effectively joining the two components together,” Gentec EO writes.

The problem with the traditional methods is that they do not deliver this heat only at the weld seam, but also to the surrounding material. The result is bending, stress, and other negative impacts on the material near the welds. Lasers, on the other hand, have enormous power density. In other words, they can deliver their heat extremely locally at the seam, leaving the surrounding materials in better condition.

Laser welds are usually so clean they do not require subsequent grinding, decreasing post-weld processing costs. Having such cosmetic welds also helps give the product a more premium look, giving a great first impression with products that are destined for end users.

Another benefit, due to a laser’s ability to weld as much as 10 times faster than traditional methods, is an increase in weld speed. Even without considering the decrease in post-processing, it’s easy to understand that faster weld speeds mean a quicker turnaround time and increased productivity.

Finally, laser welding is extremely versatile. Different laser setups can weld just about anything and everything: thick steel plates for the shipping industry, precious metals for jewelry, dissimilar metals like aluminum and steel, or copper contacts on electric car batteries.

There have even been some successful, experimental attempts to weld ceramics, a notoriously hard-to-weld class of materials.

Like any technology, laser welding does come with some disadvantages, starting with high up-front costs. “All of these advantages come at a cost, literally,” Gentec EO writes. “The initial acquisition cost of laser setups can easily be double or triple the cost of traditional systems. However, the per-unit cost is lowered. If you have sufficiently high volumes, the investment pays dividends.”

Laser welding’s precision comes with a bit of a drawback because that precision means that bad workpiece fit-up will harm the quality of the welding. This decrease in gap tolerance means you need to make sure your upstream processes/suppliers can reliably meet strict tolerance levels.

What Your Peers Think About Laser Welding

Laser welding is a precise and efficient welding technique known for its high speed, accuracy, and ability to weld thin materials with minimal distortion. Here are some insights from people who have used laser welding:

General Overview

• Precision and Speed: Laser welding is highly precise and can be very fast. It is particularly useful for thin materials and detailed work. “Laser welding is quite fast itself. Most advantages of laser welding are speed and ease of use.”
• Ease of Use: Many users find laser welding easier to learn and use compared to traditional welding methods. “Legit the ‘hardest’ part is learning what settings to use for a given situation.”

Applications and Limitations

• Thin Materials: Laser welding excels in welding thin materials like sheet metal. “It's great for really thin aluminum and stainless for example but sucks for cast, anodized, galvanized, etc.”
• Penetration Concerns: There are mixed opinions on the penetration capabilities of laser welds. Some users report strong penetration, while others find it lacking. “People that say it has no penetration have no idea what they’re talking about — if I hold it in one spot it’ll burn through my part, the table and into the concrete.” vs. “Looks cool but those welds are weak compared to normal ones.”

Practical Considerations

• Cost and Equipment: Laser welding equipment can be expensive, but some users find it worth the investment for specific applications. “I have a laser welder made in China — $12k new. Totally worth it.”
• Safety: Safety is a significant concern with laser welding due to the high energy of the laser beam. “Fiber lasers are NOT toys. They are incredibly dangerous and should be handled as such.”

Specific Use Cases

• Watch Repair: Laser welding is used in high-precision fields like watch repair to restore damaged parts. “Before and after laser welding and polish, don’t be afraid of wearing your watches.”
• Industrial Applications: It is also used in industrial settings for tasks requiring high precision and minimal material distortion. “We even smacked some t-joints with a hammer and the top plate bent 90 without breaking.”