Ultimate Guide to Laser Welding: What It Is, How It Works, and More

Laser welding is not a new technology. It was first introduced in the mid-20th century, with early experiments successfully using various types of lasers to weld metals. However, at that time, the technology was neither accessible nor affordable. It wasn’t until the early 21st century that laser welding became cost-effective and commercially available. Since then, it has gained widespread attention for its exceptional precision and high-quality welds.

In this article, we’ll explore the fundamentals of laser welding, how the process works, and examine its advantages, challenges, and everything else you need to know.

What is Laser Welding?

Laser welding is a highly precise and efficient process that uses a focused laser beam to join metals and thermoplastics. The process begins when a laser source emits a concentrated beam, which is directed at the material or joint. As the beam hits the surface, it transfers heat, rapidly increasing the temperature. This heat causes the materials to melt and fuse, creating a strong, precise weld.

Various types of lasers—such as fiber lasers, CO2 lasers, and Nd:YAG lasers—are used for different welding applications. Each laser type has unique characteristics, advantages, and limitations, which should be carefully considered based on the specific welding requirements.

Laser welding is commonly used for welding metals like steel, aluminum, and titanium, as well as thermoplastics. One of its key benefits is precision: the laser beam is incredibly fine, affecting only a small area to form the weld, resulting in exceptional weld quality with minimal distortion. Additionally, the high energy density of the laser allows for faster welding speeds, making laser welding one of the fastest welding methods available.

How Does Laser Welding Work?

The core principle behind any welding process is generating enough heat to melt and fuse the materials. In traditional welding, this heat is produced through methods like an electric arc or a flame. For laser welding, a highly concentrated laser beam generates the necessary heat, but with much greater precision and efficiency.

When the laser beam is directed at the material, it rapidly heats a small, concentrated area, causing the temperature to rise above the melting point. As the material melts, a molten pool forms, where the materials fuse together. Once the molten pool cools, it solidifies, creating a strong, metallurgical bond between the pieces.

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What sets laser welding apart is its ability to focus a high-energy beam onto a tiny area, resulting in exceptionally high energy density. This rapid energy concentration allows the materials to fuse quickly, reducing the overall welding time compared to other methods. The precision of the laser also minimizes heat distortion and reduces the risk of damage to surrounding areas.

Power Adjustment and Laser Types

The laser's power can be precisely controlled, which is crucial because different materials require different levels of heat. The laser power is adjusted according to the material being welded, ensuring optimal results. Each laser type, such as fiber lasers or CO2 lasers, has a maximum power limit depending on the source and intended application.

Shielding Gas and Its Role

During the laser welding process, a shielding gas is used to protect the molten weld pool from contaminants in the air, such as oxygen and nitrogen. Common shielding gases include inert gases like argon, helium, nitrogen, and sometimes CO2. These gases create a protective atmosphere around the weld, ensuring that the weld pool maintains its integrity and the final joint is of high quality.

Filler Materials in Laser Welding

Unlike traditional welding, laser welding typically doesn’t require filler materials. The process can weld materials directly without the need for additional substances. However, in some cases where there are gaps to be filled or to improve strength, filler materials may be added to complete the weld.

Types of Laser Welding

Laser welding can be classified into two main types based on the welding process: Conduction Welding and Keyhole Welding. Each method has its unique advantages and is suited to different applications depending on the material and desired result.

Conduction Welding

As the name suggests, Conduction Welding relies on heat conduction to melt the material. When the laser beam hits the surface, it evenly distributes heat across the material, causing it to melt without penetrating deeply into the workpiece. This makes it ideal for materials with low melting points.

In this process, the laser heat affects only the surface, causing minimal penetration and no vaporization. The result is a clean, aesthetically pleasing weld with a minimal Heat-Affected Zone (HAZ). The reduced HAZ ensures that the material surrounding the weld remains unaffected, preserving its strength and properties.

Because the process uses low power and is carried out slowly with precise control, Conduction Welding is ideal for high-precision applications. It is commonly used in industries like jewelry, electronics, and medical devices, where fine details and a smooth finish are required. Additionally, because of the lower power requirements, the equipment for conduction welding is often compact and cost-effective.

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However, this method is not suitable for thick materials or those with high melting points, as it results in a shallow penetration and a less durable weld compared to Keyhole Welding.

Keyhole Welding

In Keyhole Welding, a high-energy laser is used to create deep penetration in the material. As the laser heats the material, the temperature exceeds the fusion point, causing not only melting but also vaporization. This vaporization leaves behind a narrow cavity known as the Keyhole.

The molten pool forms between the keyhole's walls, flowing as the laser moves forward and filling the gaps. If the gaps are too deep, filler material may be introduced to ensure a solid bond and eliminate imperfections. This deep penetration process requires a powerful laser source capable of generating intense energy.

Keyhole Welding is typically used for thicker materials and those with higher melting points, making it suitable for heavy-duty applications such as aerospace and automotive manufacturing. The result is a strong, durable weld, making it the preferred choice for applications where strength and longevity are critical.

However, Keyhole Welding also has a larger Heat-Affected Zone (HAZ), which can put stress on the material and cause damage to lighter or more delicate materials.

Advantages and Disadvantages

Laser welding has become a popular choice in industries where precision, speed, and quality are paramount. While it offers several advantages over traditional welding methods, it also comes with its own set of challenges. In this section, we will explore the key benefits that make laser welding a preferred choice in many applications, as well as the potential limitations that need to be considered when choosing the right welding method for a specific project.

Advantages:

• Incredible Precision
  Laser welding offers unparalleled precision. The power, frequency, and other factors can be carefully controlled, allowing for exact welding of small and delicate items, such as electronics and jewelry. This high precision ensures clean and accurate welds with minimal distortion.
• Exceptional Speed
  Thanks to the high power density of the laser, welding joints can be made in a fraction of the time compared to traditional methods. The laser heats the material to the melting point almost instantly. The process is also highly automatable, using robotic systems to enhance speed and efficiency.
• Minimal Heat-Affected Zone (HAZ)
  Laser welding is known for its ability to focus the laser beam on a very small area. This concentration of heat results in minimal heat stress on surrounding material, reducing the risk of damage to adjacent components and minimizing the Heat-Affected Zone (HAZ).
• Clean, Smooth Welds
  Laser welding produces extremely clean and smooth welds with minimal spatter or distortion. Since the process affects such a small area, post-weld cleanup is often unnecessary, reducing overall labor and time spent on finishing.
• Versatility
  One of the key benefits of laser welding is its ability to work with a wide range of materials, including metals, plastics, and even dissimilar materials. This versatility makes it a preferred choice for many industries, from aerospace to medical devices.
• Low Operational Costs
  Laser welding is a cost-effective solution for many applications. It does not require filler materials, and its energy consumption is relatively low due to the focused laser beam. Additionally, the speed of the process increases overall productivity, and minimal post-processing is needed, further reducing costs.

Disadvantages

• High Upfront Cost
  The initial investment for laser welding machines can be significant. These machines are more expensive than traditional welding equipment, and the cost increases with higher power laser systems and advanced features. This can be a barrier for smaller businesses.
• Safety Concerns
  The intense energy of the laser beam requires careful handling. Improper operation can lead to serious injuries. Adequate safety measures and protective gear are necessary to ensure operator safety during the process.
• Limited Penetration Depth
  Laser welding generally doesn’t penetrate as deeply as traditional welding methods. This limitation can be problematic for certain applications, especially when working with thick materials or requiring deep welds. Factors like the focused laser spot and material properties contribute to this challenge.
• Material Limitations
  Some materials are not well-suited for laser welding, particularly those with high reflectivity or high thermal conductivity. Materials like aluminum and copper may pose challenges without specialized equipment, making them less compatible with standard laser welding processes.
• Requires Specialized Skills
  Operating a laser welding machine is not as straightforward as traditional welding. Operators must be knowledgeable about various factors, such as power levels, laser wavelength, and material compatibility, to achieve optimal results. Proper training and expertise are essential for successful operation.

Fields of Application

Aerospace

The aerospace industry requires quality welds. It needs high precision and accuracy to weld some expensive materials. The weld should be smooth and clean, and at the same time, it should be strong enough to withstand the conditions in space. That’s why laser welding is an ideal option.

The materials used in the industry are pretty expensive, so there should be minimal chances of errors and damage. And post-processing of materials like in traditional welding could affect the material. 

Laser welding can meticulously weld materials used for aerospace projects. It’s able to focus even on tiny parts without disturbing the surrounding area. The surrounding area is not under heat stress or damage. Therefore, it is suitable for welding lightweight and thin materials and creates reliable and strong welds.

Automotive

In the automotive industry, a strong and clean weld is needed. High strength is required to bear extreme road conditions, while exceptional smoothness is necessary to keep the aesthetics of the vehicle. 

Laser welding is a great option because it’s flawless and fast, and almost no post-processing is needed. And most importantly, during the welding process, it does not deform the material and affect other areas. It’s extremely precise and under control.

Another great feature of laser welding is incredible speed. The automotive industry requires fast processing due to massive demands. Laser welding can save time and increase productivity.

On the macro level, laser welding is used in the automotive industry to create joints in the chassis, body panels, and other parts. The joints are smooth and seamless and require minimal post-processing. They are neither visible nor feelable after paint, so they do not affect the aesthetics in any way.

On the micro level, they can also be used to create some small joints, such as electronic components. They are capable of targeting small areas that are not possible with other types of welding.

Medical

Extreme precision and accuracy are needed in the medical industry. For instance, surgical instruments are very complex and have tiny components. They require meticulous welding without affecting the neighboring area of the instrument. That’s why laser welding is a feasible option. It can do the job without damaging delicate components and affect the quality of the instrument.

Similarly, medical implants, such as pacemakers and orthopedic devices, require clean and precise welds. There is no option for post-processing. Therefore, laser welding is used in the fabrication of such implants to make them flawless.

Laser welding is also a great option for the medical industry because it’s a no-contact process. It does not contaminate the working piece. It ensures sterility and hygiene.

Electronics

The electronics industry deals with tiny components that cannot be handled with bare hands. Welding them on the PCB or chips is not an easy task. It requires incredible precision and control. The heat should not affect the delicate components around. Therefore, the perfect option is laser welding. It helps in connecting tiny components with extreme accuracy.

Similarly, the connections of sensors, actuators, and other delicate devices are also done through laser machines. It creates a meticulous weld that is not only clean but also reliable. You might have seen laser welds on lithium-ion battery terminals. These welds are just like dots and do not harm the battery itself or occupy any space.

Jewelry

Laser welding is the best option for jewelry making because of its focused beam, incredible precision, high control, and no effect on the surrounding area. It is compatible with precious metals, such as Gold and Silver.

With laser welding, it’s quite easy to weld intricate and delicate jewelry pieces and items. Within a blink of an eye, it welds with exceptional quality. 

Laser welding is to make custom designs for customers in minimal time. It’s also capable of joining dissimilar metals. Apart from that, it is used for repairing jewelry pieces and resizing.

Suitable Materials for Laser Welding

Unlike traditional welding methods, which primarily focus on metals, laser welding is highly versatile and can be used on a wide range of materials, including thermoplastics. The process is effective on any material that can be melted and solidified again, making it suitable for a variety of metals and plastics.

Laser welding is commonly used to join different types of metals, including steel, aluminum, and copper. One of its key advantages is the ability to weld dissimilar metals, such as steel to aluminum or stainless steel to carbon steel. However, joining different metals requires careful consideration of the materials involved and may require additional techniques like Laser Brazing, which involves using filler materials to create a strong bond.

Metals:

• Steel
• Aluminum
• Copper
• Nickel
• Titanium
• Magnesium
• Gold
• Silver

Plastics:

• Acrylic
• Polycarbonate (PC)
• Polyethylene
• Thermoplastic Polyrethane (TPU)
• Nylon

The compatibility of laser welding with such a wide variety of materials makes it a versatile and efficient solution for many industries, from automotive to electronics.

Safety Considerations in Laser Welding

Laser welding is a powerful and precise process, but it comes with significant safety risks due to the high energy density of the laser beam. If the beam is reflected from the surface, it can cause serious harm to the operator’s eyes or skin. Additionally, the concentrated energy can damage nearby objects and, in some cases, even ignite fires.

Enclosed Laser Machines

Laser welding machines should be fully enclosed to prevent the escape of laser beams. This ensures that the operator and others in the area are protected from accidental exposure.

Safety Gear

Operators must wear proper laser safety eyewear and protective clothing designed to meet safety standards. This gear is essential to prevent eye and skin injuries caused by the laser’s intense energy.

Fire Safety

It’s crucial to keep flammable materials away from the welding area, as they can easily ignite. The facility should be equipped with the necessary fire safety equipment to quickly address any potential fire hazards.

Fume Extraction

Laser welding generates fumes that can be harmful to the operator’s health. A well-maintained exhaust system and proper ventilation are required to safely dispose of these fumes. Operators should also have adequate respiratory protection to minimize exposure.

Training and Emergency Procedures

Operators should undergo thorough training, and safety procedures (Standard Operating Procedures or SOPs) should be followed. Clear warning signs and emergency protocols must be in place to handle any accidents that may occur.

Other Facts about Laser Welding

How does laser welding compare to other welding methods?

Laser welding is a no-contact process that uses a concentrated laser beam to rapidly increase the material’s temperature and melt it. It is more precise than traditional welding, resulting in a small heat-affected zone and faster welding speeds. It can also weld a wider variety of materials.

How much does a laser welder make a year?

The average salary for a laser welder ranges from $40,000 to 50,000 annually, depending on expertise, experience, and the industry in which they work.

How much does a laser welder make a year?

Laser welding is typically used for thin to medium-thick materials, usually up to 5mm. However, with higher power lasers, it can weld thicker materials, though this requires significantly more energy.

Conlusion

Laser welding has gained popularity across industries due to its many benefits, including high precision, speed, clean welds, and low operational costs. As technology continues to advance, laser welding machines are becoming more affordable, with handheld and portable options now available. The technology has evolved significantly since its introduction and is now becoming increasingly common in various applications.