Laser welding is the process of using the energy of a laser beam to melt the surface of materials, thereby achieving material welding. The laser beam is focused into a tiny point through lenses or reflectors, allowing the laser beam to concentrate energy in a very short time, raising the temperature of the workpiece at the welding area above the melting point, producing a molten state, and then cooling and solidifying to form a weld seam.

Important Parameters of Laser Welding Machines

1. Power Density

Power density is one of the most critical parameters in laser processing. With higher power density, the surface can be heated to the boiling point within microseconds, producing a large amount of vaporization. Therefore, high power density is beneficial for material removal processes such as drilling, cutting, and engraving. For lower power density, it takes milliseconds for the surface temperature to reach the boiling point, and before surface vaporization, the bottom reaches the melting point, which is conducive to the formation of a good fusion weld.

2. Laser Pulse Waveform

When a high-intensity laser beam is irradiated onto the material surface, 60-98% of the laser energy will be reflected and lost, especially for materials such as gold, silver, copper, aluminum, and titanium, which have strong reflectivity and fast heat transfer. During a laser pulse signal process, the reflectivity of the metal changes over time. When the surface temperature rises to the melting point, the reflectivity drops rapidly, and when the surface is in a molten state, the reflectivity stabilizes at a certain value.

3. Laser Pulse Width

Pulse width is an important parameter of pulsed laser welding. The pulse width is determined by the depth of fusion and the thermal influence zone. The longer the pulse width, the larger the thermal influence zone, and the depth of fusion increases with the square root of the pulse width. However, increasing the pulse width will reduce the peak power, so increasing the pulse width is generally used for conduction welding methods, forming wide and shallow welds, especially suitable for lap welding of thin and thick plates.

However, lower peak power can result in excessive heat input, and each material has an optimal pulse width that maximizes penetration depth.

4. Focus offset

Laser welding usually requires a certain amount of focus offset because the power density at the center of the laser focus is too high and is prone to evaporate into holes. On planes away from the laser focus, the power density distribution is relatively uniform.

5. Welding Speed

Welding speed has a significant impact on penetration depth. Increasing the speed will make the penetration depth shallower, but too low a speed will cause excessive melting of the material and workpiece penetration. Therefore, for a certain laser power and a certain thickness of a specific material, there is an appropriate range of welding speeds, and the maximum penetration depth can be obtained at the corresponding speed value.

6. Protective Gas

In the laser welding process, inert gas is commonly used to protect the weld pool. Helium, argon, nitrogen, and other gases are commonly used for protection in most applications. The second function of the protective gas is to protect the focusing lens from metal vapor contamination and liquid droplet spattering. In high-power laser welding, spatter is very powerful, so protecting the lens is more necessary at this time. The third function of the protective gas is to effectively disperse the plasma shielding generated by high-power laser welding. Metal vapor absorbs laser beams and ionizes into plasma. If there is too much plasma, the laser beam will be consumed to some extent.

Advantages of Laser Welding Machines

Using the extremely high energy density of the laser beam to fuse materials is currently the most advanced welding method in the processing field. Compared with traditional welding technology, laser welding technology is a non-contact welding method, and the operation process does not require pressure. It has the advantages of fast welding speed, high strength, large depth, small deformation, narrow weld seam, small heat-affected zone, small workpiece deformation, less post-welding processing work, reduced manual output, high flexibility, and more safety.

Laser welding technology can weld difficult-to-melt materials such as high-melting-point metals, and can even be used for welding non-metallic materials such as ceramics and organic glass. It has good welding effects on irregular materials and has great flexibility. For welding parts that are difficult to access, flexible transmission non-contact welding is performed. The laser beam can achieve spectral separation in time and energy and can process multiple beams simultaneously, providing conditions for more precise welding.

Applications of Laser Welding Machines

1. Sanitary Ware and Kitchenware Industry

Laser welding has a precise and attractive appearance, so it is widely used in high-end stainless steel products such as handles, faucets, stainless steel cutlery knives, and high-end electric kettles for laser marking and laser welding. The sealing of kitchenware and utensils, welding, mold making, and repair and modification during the mold production and use process.

2. Digital Products, Mobile Phones, and Computer Industry

Due to its precise processing technology, laser welding is more popular in the digital, mobile phone, and computer fields, such as laser welding of mobile phone, MP4, and MP3 casings, spot welding of interface cables, welding of notebook computers, and connectors for fiber optic equipment.

3. Engineering Machinery Industry

Welding of purification equipment, electromechanical accessories, and bearing repairs.

4. Electronics and Electrical Industry

Since laser processing is a non-contact processing method, it does not produce mechanical squeezing or mechanical stress, so it is particularly suitable for the processing requirements of the electronics industry. Welding of transformers, inductors, connectors, terminals, fiber optic connectors, sensors, transformers, switches, mobile phone batteries, microelectronic components, and integrated circuit leads.

5. Jewelry Industry

Due to the high precision of laser processing, it is very suitable for precious and small products in the jewelry industry. Since the laser focus beam is very fine, the fine parts of jewelry can be magnified through a microscope for precise welding. Welding of jewelry chain connections and setting of gemstones require the use of laser spot welding machines, which are essential equipment.

6. Hardware, Tools, and Instrumentation Industry

Welding of instruments, sensors, kitchenware, and utensils, mold making and repair during the mold production and use process. Seamless welding of stainless steel cutlery, welding of instrument core connections.

7. Automotive and Electric Vehicle Industry

Laser processing is non-contact processing, pollution-free to products, high speed, and more suitable for the production process of high-end automotive consumer goods, such as welding of car dashboard, car doors, piston rings, car cylinder gaskets, exhaust pipes, filters, and automotive safety airbag generators. Laser cutting of automotive trial production and small batch production stage parts, battery welding of electric vehicles.

8. Energy, Lighting, and Building Materials Industry

Laser processing is widely used in the manufacture of laser solar cells: such as laser cutting of solar silicon wafers and laser welding of thermal plates for solar water heaters. Laser processing, as an environmentally friendly and efficient processing method, will receive even broader applications in the future.