Laser Welding: Importance, Types, Applications

Welding is the technique of joining two materials with flame at a high temperature. This method of linking two materials is commonly employed in thermoplastics, metals, and even wood. These materials can be welded using several methods. We’ll take a look at one of the most modern methods of welding: laser welding.

Laser welding is a technique that uses a lens to focus light with high proximity and convergent forces, producing higher-energy-density beams that act as a source of heat.

What is Laser Welding?

Laser (Light Amplification by Stimulated Emission of Radiation) welding is a process of connecting metals or thermoplastics using a laser beam to form the joint. It is a way of joining metal or thermoplastic substances using a laser to form a joint called a weld. It is a high-power-density fusion welding technique that produces high-aspect ratio welds with lesser heat inputs compared to traditional arc welding techniques. It is an extremely sophisticated technique for welding, featuring uses that range from aviation and medical devices to fine jewelry fabrication.

The independent laser light source generates the laser beam, which is aimed at the component being worked on by a collimator, or “torch” that can be handled by a person or mounted on a piece of machinery. The focused beam then heats and melts the target pieces and the ensuing hot melt pool joins the intended targets together to make a well-integrated weld. There are different types of laser welding which are discussed below.

Types of Laser Welding

There are different types of laser welding based on the materials they work, cost, efficiency, and availability. Here we are going to look at some of the major types of laser welding techniques.

Fiber Laser Welding

• In fiber laser welding, laser light is produced in an active fiber and directed to the workpiece through a flexible delivery fiber that serves as a “light guide”.
• This approach employs a concentrated laser beam to melt the material. It provides a localized heat source for welding the metals together.
• During this procedure, diode lasers emit light. Following amplification, the emitted light is sent through a fiber optic connection.
• The process involves adjusting the laser beam’s wavelength to fit the application. It works by gathering pumping light generated by the laser.
• The ability to distribute this laser beam in a wide range of methods is vital for various types of material processing, including laser cutting, welding, marking, and engraving.
• As this technique involves rapid cooling and heating, the duration of welding is reduced compared to standard welding methods.
• Fiber laser welding has applications in a variety of businesses, including automobiles, aviation, electronics, healthcare, defense, and construction.

Deep Penetration Laser Welding

• Deep penetration laser welding is a form of welding that uses an extremely powerful laser beam to penetrate the workpiece to a substantial depth.
• It is designed exclusively for welding thick materials especially producing strong weld connections with high depth-to-width ratios.
• A high-power density laser beam is directed to the workpiece’s joint, creating deeper welds; the laser’s intensity contributes in achieving the intended outcome.
• The laser beam heats the material, which subsequently vaporizes and creates a cavity in the workpiece.
• This removes the need for complicated joint preparation or multiple welding rounds by allowing for the welding of thick materials in a single pass.
• The procedure provides fast welding rates, great weld quality, and low heat input, resulting in minimum deformation and a tiny heat-affected zone.
• Deep penetration laser welding is additionally known for its ability to combine materials with high melting points and different compositions.

Laser Spot Welding

• Laser spot welding is a welding method that applies the heat of a laser beam to form a weld between two separate metal surfaces at a single spot.
• The laser beam concentrates its energy on a narrow area, melting and fusing metal surfaces.
• This process is quick, precise, and capable of welding a variety of metals, dissimilar metals.
• Laser spot welding concentrates the laser beam into a small area, approximately 0.1 to 2 millimeters in diameter.
• The narrowed heat-affected zone minimizes the possibility of deformation or damage to the adjacent material.
• Furthermore, the non-contact nature of laser spot welding reduces the risk of impurities or external stains on the workpiece.
• This approach is commonly used for coil welding, notably in electronics and electrical engineering, where sub-100-micron spot welding techniques are necessary.
• It is also used in the medical industry to create medical equipment and implants.

CO₂ Laser Welding

• CO₂ laser welding is a method utilizing a carbon dioxide-based laser beam for welding metals.
• It is widely utilized in an array of industries as it is a convenient and adjustable welding technology.
• With the aid of lenses and mirrors, a laser beam including nitrogen, carbon dioxide, and helium is combined with other gases to create CO₂ laser welding.
• The intense radiation produced by the laser beam accelerates the melting of the metal’s surface and enables both workpieces to fuse together.
• Numerous industries, including the transportation, aviation, gadgets, and manufacturing industries, utilize CO₂ laser welding.
• Body panels, chassis sections, exhaust systems, and electrical enclosures are among the components that are commonly welded using this technique.
• Due to its versatility, CO₂ laser welding can be used to weld a variety of metals, such as stainless steel, aluminum, and steel.

Conduction Mode Laser Welding

• A conduction mode laser welding requires less power and has an inferior energy density. The end result of the weld is shallow and broad, nearly bowl-shaped.
• This method of welding simply warms the components until they melt, flow together, and solidify.
• Conduction laser welding is ideal for welding thin materials or those with low heat conductivity.
• The overall width of a conduction weld remains greater than its depth, which makes it ideal for merging thin-walled materials for spot welding.
• It provides fine control over the welding operation. This reduces faults in the final weld.
• This welding procedure is commonly used in the healthcare equipment, electronic devices, and jewelry fabrication sectors.

Keyhole Laser Welding

• A deep and small hole is welded into the workpiece using a sophisticated technique called keyhole laser welding. The term “keyhole” describes an actual hole created by the material vaporizing, enabling the energy beam to pierce deeper.
• A high-power laser beam is used in the keyhole welding process to deliver a strong focus which forms a keyhole.
• A deep, thin profile with an aspect ratio more than 1.5 characterizes a keyhole mode weld.
• As the beam passes through the material, molten metal flows around the keyhole, filling the space and sealing the weld.
• Keyhole laser welding also creates weld connections with low distortion and high weld quality.
• This welding process is widely utilized in industries like automobiles, aviation, and metallurgy.
• This method is also used to weld the turbine blades, spaceship valves, tank bearings and many more.

YAG Laser Welding

• YAG laser welding is distinguished by its unique ability to concentrate strong heat on a tiny region, resulting in deep penetration and great precision.
• The procedure involves melting the materials to be bonded and allowing them to solidify, resulting in a strong and long-lasting bond.
• There are three different types of YAG laser welding: (i) Nd:YAG laser welding, (ii) Diode-Pumped laser welding, and (iii) Fiber-Delivered laser welding.
• Nd:YAG laser welding is a form of welding technology that uses a solid-state laser called a neodymium-doped yttrium aluminum garnet (Nd:YAG) beam to connect metal parts together.
• YAG lasers provide precise control of the welding procedure, allowing for top-notch welds. The laser beam enables deeply penetrated welding. This method is ideal for thicker materials.
• It reduces the heat affected zone (HAZ), lowering the risk of material distortion while maintaining the mechanical qualities of the welded components.
• It produces a wavelength of 1064 nanometers and is ideal for welding materials such as aluminum, copper, and other alloys.
• It is important in the automobile industry since it allows for the creation of lightweight, fuel-efficient vehicles. It’s used to weld body panels, exhaust systems, and suspension parts.
• In the aerospace industry, this method is used to combine complicated and heat-sensitive materials, assuring structural integrity of aircraft components while reducing weight.
• It also has uses in the medical industry, particularly in the manufacture of medical equipment and implants. Its precision and low heat impacts make it perfect for producing small, delicate welds.

Remote Laser Welding

• Remote or scanner laser welding is a distinct form of laser welding technology. Remote laser welding systems feature extended focal lengths, and a laser beam mounted above rapid deflecting mirrors. These types of systems are typically connected with industrial robots.
• It is a specially developed method used in laser welding in which the laser beam is transmitted onto the workpiece through optical fiber cables or similar beam delivery devices.
• Enhanced accessibility to challenging-to-reach places or intricate geometries is one of the many benefits of this remote operation.
• 3D components with many shorter joints, such as automotive doors, front seats, and other structural parts, are ideally suited for the use of this method.

Hybrid-Laser Welding

• Hybrid laser welding is the process of welding materials utilizing both laser welding and classical welding (arc welding). The approach employs a strong laser ray and traditional arc procedures to improve welding speed and quality.
• MIG, TIG, MAG, and plasma represent some of the compatible classical welding processes that can be combined with a laser heat source to accomplish hybrid laser welding.
• The laser beam is the primary heat source in laser-hybrid welding, delivering a focused and strong energy stream to the joint. The laser beam quickly heats the metal, melting it and leaving a pool of molten weld. At the same time, the filler material is supplied, and the weld pool is heated using an arc welding method.
• Because of its great productivity and low distortion, hybrid laser welding is employed in the production of construction materials and structures. The new welding technology contributes to higher levels of endurance, structural efficiency, and cost effectiveness.

Laser Transmission Welding

• Other names for transmission welding or laser transmission welding include laser plastic welding, through-transmission welding (TTLW), and laser polymer welding.
• Unlike normal welding, which applies energy to the surface of the materials. Transmission welding tries to transfer energy between two plastic components at their interfaces.
• Transmission laser welding of polymers is a welding method that uses laser light sent using a transparent upper section to unite two or more polymers sections.
• It involves the bottom part absorbing laser energy, that is typically made of an opaque substance, generating heat and melting the contact between the pieces.
• The laser beam passes through the translucent upper component with little absorption or melting, resulting in highly accurate and concentrated heating at the joint interface.
• After the laser energy is removed, the molten material hardens, producing a strong and dependable weld.
• It is widely used in a variety of industries where the effective and superior joining of polymer components is required, such as the manufacturing of household products, electronics, cars, and medical equipment.

Science of Laser Welding

• A concentrated, collimated, high-intensity beam of light is used in laser welding to melt and fuse metal components, occasionally with an inclusion of additional material as a filler rod.
• The method involves producing laser light and directing it toward an optical head or collimator. The heat is thus concentrated at the metal-to-metal interface, resulting in a limited melt pool and intensely concentrated accumulation of heat.
• Generally, a solid-state, fiber, or CO₂ laser produces the laser welding beam; each has pros and cons of its own.
• At the beam’s focal point, the metallic substance melts and creates a confined pool into which the filler rod can be melted as desired.
• The emitted laser beam is then directed towards the joint’s surface. This melts a leading edge then allows the pool’s molten, welded edge behind it to cool and solidify.
• When a weld is successful, the cooled metal fuses to both pieces almost identically and doesn’t oxidize.

Procedure of Laser Welding

When you perform the laser welding you need to take care of some important things. We are going to look at the procedure to follow during the laser welding.

Cleaning

• Align and clean the weldable components precisely. A closed, gapless contact line improves weld quality.

Stability

• Manual clamps or automated fixtures is necessary to hold the work pieces in position and stabilize them throughout the welding process.

Adjusting Focal Point

• Set the beam’s center of focus to the welding zone. The optical gear of a welding torch generally facilitates effortless focus adjustment.

Maintain Beam Energy

• Test the beam’s intensity on sample pieces and scrap material after adjusting it. Verify that it is emitting a sufficient amount of heat to cause melting of the substrate while not releasing excessive energy that enables to overheat the parts before going on to the workpiece.

Controlled Motion

• Begin putting on the beam of light where the welding process will take place. Once a suitable melting pool is formed, it needs to be moved steadily down the weld.

Apply Traditional Welding Methods

• Hot point rotation is a traditional welding process that promotes good fusing and improves weld quality.

Cooling

• When the welding process is complete, let the component cool normally. In addition, you can utilize further cooling measures or soak it in water.

Factors Impacting Laser Welding

There are several factors that can influence the outcome of the weld. Some of these variables must be considered in order to select the appropriate type of laser welding for the specific application.

Compatibility of Materials

• While fabricating parts, multiple materials are welded together; each material has distinct thickness and features. As it turns out, while selecting a laser form, an examination of the substrate is critical.
• For thicker materials, deep penetration or keyhole welding may be required, but fiber lasers perform effectively on almost any material.
• Certain materials, which include exceptionally reflective metals, remain challenging to weld with lasers given that light normally reflects off their surfaces.
• Similarly, some polymers and composites are difficult to weld due to their low heat conductivity.

Preparation of Joints

• The type of connection or weld affects the choice of laser welding techniques as well.
• Effective joint preparation is essential for a laser welding operation to succeed smoothly.
• Certain lasers may not be suitable for all weld types, whilst others may.
• The joint surfaces need to be correctly aligned and free of contaminants.
• Any misalignments or gaps in the joint can result in incomplete welds or weak joins.

Controlling Welding Speed

• The type of laser welding technique must be used is determined by the manufacturing need and volume.
• Some of them aid in high-volume, high-speed production, and are required for certain applications.
• The disk lasers provide a high laser beam quality, as well as a high laser power, which aids in the production of high-speed welds.
• Achieving the appropriate weld qualities requires careful management of the laser’s power, speed, and focus.

Heat Impact

• The effect of heat on the material by the laser weld must also be taken into account. 
• Certain methods create less heat, reducing the extent of the heat-affected zone.
• Pulsed laser welding is suitable since it reduces the influence of heat on the environment.

Safety of The Operator

• These types of laser welding can pose a safety threat to the operator.
• The laser’s powerful light and heat can injure the eyes and skin.
• Therefore safety masks, suits, and eye goggles should be used by the operator and the people in the vicinity of the machines.

Cost of Laser Welding

• It’s important to evaluate the expenses of laser welding equipment and select the right laser based on your financial limitations.
• Smaller businesses or groups may struggle to cover the initial expenditures of laser welding equipment.
• Maintenance and repair costs can also be high, increasing the overall cost of laser welding.
• Diode laser welding is among the least expensive techniques for welding.

Materials Welded Using Laser Welding

Laser welding can be used in number of material. We are going to look at some of the materials that uses laser welding method.

Metals

• This method’s applicability to a larger range of activities than conventional thermal or electrical welding processes are increased by its ability to join components of significantly varying thicknesses.
• Metals with different thickness be it thin or thick this method can weld it.
• Copper, Aluminum, Gold, Nickel are some of the many metals that can be welded using laser welding.

Plastics

• We have already mentioned about the laser polymer welding method being able to weld the thermoplastics.
• It is widely used in a variety of industries where the effective and superior joining of polymer components is necessary.
• The two polymers’ comparable melting and softening ranges are the most crucial component. As a result, both polymers will melt at around the same moment.
• Certain thermoplastics can be welded with lasers, such as ABS, nylon, and polycarbonate.

Composites

• Carbon fiber-reinforced polymers (CFRPs) can be processed using this method.
• Additionally, there has been cutting-edge research and early success with metal components lasers welded to carbon fiber composites.

Ceramics

• Ceramics are able to be welded together through laser welding.
• Alumina and zirconia are welded using laser welding techniques.
• These along with other ceramics can be melted and fused using lasers in ways that are far more difficult to do with traditional thermal methods.

Advantages of Laser Welding

Compared to conventional welding techniques, laser welding offers a number of special benefits, including:

Higher Accuracy and Precision

• Laser welding provides great levels of precision as well as accuracy.
• Laser welding is a precise welding process that produces microscopic, complicated welds with excellent accuracy
• These properties allow us to weld even the smallest parts together without causing damage or significant thermal deformation.

Better Quality

• Laser welding technique is a contact-free welding approach that makes use of minimal amounts of heat, reducing the possibility of thermal and mechanical distortion.
• Laser welding produces welds that are consistently mechanically sound and of excellent quality.
• Welds are typically free of flaws like permeability, inclusions, and cracks.

Versatility

• Laser welding can be used to combine many different materials, including metals, polymers, and even some ceramics.
• The laser welding process may support a variety of weld joint configurations.
• It is able to handle different welding materials, galvanized metals, and even magnetized materials.
• The procedure can also be used to join dissimilar materials, which is typically unachievable with other welding techniques.

Operation Speed

• Laser welding is a considerably faster technique, allowing for increased manufacturing output.
• A melt pool warms up quickly due to the high concentration of energy. Heat spreads quicker compared to traditional methods of welding.

Automation

• Until laser welding became widely automated, the only way to achieve high-volume output and consistent quality was through spot welding.
• This is especially critical in the automobile, aerospace, and electronics industries, where accuracy and repeatability are essential.

Applications of Laser Welding

Laser welding offers a variety of applications due to its high precision, short processing time, wide material tolerance, and consistent quality. Some of the major applications are discussed here.

Electronic Industry

• In the electronics industry, laser welding is used to combine small and sensitive components such microelectronic devices, sensors, and connectors.

Tool Construction

• The laser welding system’s high precision makes it ideal for tool manufacture. The technology enables the production of precision pressing, punching, and casting tools.

Steel Industry

• Because of its great productivity and output, laser technology is used in the steel construction industry.
• Thick metal sheets can be processed quickly and with great precision using laser welding.

Automobile Industry

• With its tool-free method of operation and no need for head replacement, laser welding is a great fit for the automobile sector.

Airspace Industry

• The aerospace industry employs laser welding to join critical components such as turbine blades, fuel nozzles, and aircraft structural sections.

Energy Sectors

• Power generation systems, including fuel cells, batteries, and solar panels, are assembled using laser welding in the energy sector.

Medical Equipment’s

• Laser welding is frequently utilized in the manufacture of medical devices, including surgical instruments, implants, and dental appliances.

Jewelry Industry

• The watch and jewelry industries employ laser welding to precisely attach delicate components and expensive metals.

Video Reference

References

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