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Key considerations for laser welding of dissimilar materials

Several key factors need to be considered when welding dissimilar materials:

A. Material matching and compatibility
When selecting dissimilar materials for welding, compatibility must be considered, especially in terms of chemical composition, melting temperature and thermal expansion coefficient. These factors directly affect the stability and quality of the weld.

1. Chemical composition compatibility: Differences in the chemical composition of different materials may lead to the formation of unfavorable compounds or oxides during welding, thereby affecting the quality of the weld. Appropriate filler materials need to be selected to avoid these adverse reactions.

2. Melting temperature matching: Differences in the melting temperatures of dissimilar materials will lead to uneven heat distribution during welding, affecting the welding effect. Controlling the temperature of the welding heat source to ensure that both materials can melt smoothly is the key.

3. Thermal expansion coefficient difference: Different thermal expansion coefficients between materials will generate stress during welding and increase the risk of cracks. This problem can be alleviated by optimizing the welding design and appropriate heat treatment.

4. Alloy filler material: For materials that are difficult to be compatible, the use of alloy filler materials can help improve the welding effect and enhance the strength and durability of the weld.

5. Welding process selection: Selecting a suitable welding process, such as laser welding, TIG welding, etc., can effectively reduce the incompatibility between materials and ensure the stability of the welding process.

By reasonably selecting alloy filler materials, welding methods, and controlling heat input, the stability and quality of dissimilar material welding can be effectively improved.

B. Optimal laser parameters
In laser welding, selecting the correct laser parameters is the key to ensuring welding quality, especially when welding dissimilar materials. The following is a brief introduction to laser parameters:

1. Laser power: Laser power directly affects the depth and width of the weld. When the power is too low, it may not be able to achieve sufficient melting depth, resulting in incomplete welding; too high power may cause overheating, burn-through, or material deformation. Dissimilar materials have different thermal conductivity and melting temperatures, and the laser power needs to be precisely adjusted to ensure uniform temperature in the weld area and avoid defects.

2. Pulse frequency: The pulse frequency affects the heating and cooling speed of laser welding. Higher pulse frequencies are suitable for thinner materials, while lower frequencies are suitable for thicker materials. When welding dissimilar materials, the pulse frequency needs to balance the difference in thermal conductivity of the two materials to avoid cracks or weakened joints due to too fast or too slow cooling.

3. Scanning speed: The scanning speed affects the heat input and welding quality. If the scanning speed is too fast, the molten pool may not be fully fused, resulting in incomplete welding; if the scanning speed is too slow, it may cause overheating, resulting in cracks in the joint area, or the heat-affected zone is too large. Choosing the right scanning speed can ensure that the heat is evenly distributed in the welding area.

4. Focus position and spot size: The position of the laser focus determines the concentration of the heat source and affects the accuracy and quality of the welding. If the focus position is too high or too low, it will affect the welding result, resulting in overheating or incomplete melting. Correctly setting the focus and spot size helps to achieve ideal heat input, especially when welding different materials, it needs to be adjusted according to the light absorption rate and thermal conductivity of the material.

5. Heat input control: The heat input during welding determines the quality and performance of the welded joint. Excessive heat input may cause excessive melting of the material, resulting in thermal cracks or deformation; too little heat input may cause incomplete welding. By precisely controlling parameters such as laser power, scanning speed, and pulse frequency, heat input can be optimized and welding quality can be guaranteed.

6. Selection of welding method:
Precisely adjusting laser welding process parameters can ensure uniform temperature distribution in the welding area and avoid welding defects, especially when welding dissimilar materials. By adjusting factors such as laser power, pulse frequency, and scanning speed, the welding quality can be greatly improved and the strength and stability of the welded joint can be guaranteed.

C. Selection of filler materials
When welding dissimilar materials, filler materials are very important. Suitable filler materials can improve the strength, corrosion resistance, and wear resistance of welded joints. The selection should be based on factors such as the composition, melting temperature, and thermal expansion coefficient of the welding material.

1. Improve welding strength: Suitable filler materials can improve the strength of welded joints, especially when welding dissimilar materials, and can balance the strength differences between different materials and avoid welded joints being too fragile.

2. Improve corrosion resistance: Selecting corrosion-resistant filler materials (such as nickel-based alloys, chromium alloys, etc.) can enhance the corrosion resistance of the joint, especially for welding materials such as stainless steel and aluminum alloys.

3. Improve wear resistance: For welding joints that need to withstand friction, the use of wear-resistant filler materials (such as hardened alloys) can extend the service life of the joints.

4. Match welding material composition and temperature: The filler material should match the composition and melting temperature of the parent material to ensure stability during the welding process and avoid defects caused by mismatch.

In summary, the selection of suitable filler materials can significantly improve the welding quality and ensure the mechanical, corrosion and wear resistance of the joint.

When laser welding dissimilar materials, material pairing and compatibility, laser parameter optimization, and the selection of filler materials are key factors to ensure welding quality and effect. Reasonable selection of compatible material combinations can improve the stability of the welding process and avoid welding defects; precise adjustment of laser parameters to ensure uniform heat distribution and avoid overheating and poor welding; suitable filler materials can improve the mechanical properties and durability of welded joints. Taking these factors into consideration, high-quality welding of dissimilar materials can be achieved to meet the high standards of modern manufacturing. 

How can laser cleaning machines benefit the food industry?

Laser cleaning technology ensures that most of the dirt evaporates and the remaining residues fall loose. Not only does the laser cleaning machine clean more thoroughly than traditional methods, but the heat generated by the laser beam also has antibacterial properties, which can effectively remove bacteria and microorganisms from the surface of the substrate. In addition, laser cleaning machines reduce harm to the environment and human health, making them an indispensable innovative technology in the development of the food industry.

Today, we will explore some basic knowledge about laser cleaning machines. In addition, we will also discuss the application of laser cleaning machines in the food industry. We hope that this article will help you choose a laser cleaning machine that suits your needs.

What is laser cleaning technology?

Laser cleaning technology uses high-intensity laser beams to remove oil, rust, oxides and other residues from the surface of metals and other materials.

Thermal decomposition: When the laser beam is irradiated to the surface of the target material, the temperature rises rapidly due to the energy of the beam, accelerating the heating and evaporation of the contaminants. This process is similar to breaking down dirt with high temperatures and is particularly suitable for removing stubborn grease and coatings.

Photolysis: High-energy laser photons interact with contaminant molecules and break molecular bonds. This photolysis effectively removes complex chemical contaminants such as paint and oxide layers.
What are the benefits of laser deep cleaning?

1. Extend equipment life

One of the main advantages of laser cleaning machines is the contactless cleaning process. Contactless means that when dealing with grease and other contaminants, no mechanical tools are required to remove them, and no chemical cleaners or abrasive grinding is required, because the cleaning medium is a high-energy laser beam. The laser beam only acts on surface contaminants without applying friction or pressure to the substrate. Therefore, using a laser cleaning machine will not cause wear and tear on your production equipment.

2. Achieve precise cleaning

The laser beam in the laser cleaning machine can be focused into an extremely small spot with a diameter as small as a few microns. This concentrated energy enables the laser cleaning machine to work in very small areas, such as grooves and narrow spaces that are difficult to clean. In addition, the laser cleaning machine can adjust the pulse width and frequency of the laser according to your cleaning needs. For example, short pulse widths are suitable for removing thin layers of contaminants, while high frequencies can be used for large-scale cleaning. Finally, the laser power can be precisely adjusted according to the complexity of the cleaning task. Lower power is suitable for removing light dirt, while higher power can be used to remove stubborn oxide layers or rust.

3. More hygienic and safer

In the food industry, keeping workbenches and equipment clean is essential for food safety control. Generally, the temperature generated by lasers can reach hundreds or even thousands of degrees Celsius, which is enough to denature bacterial proteins, damage DNA, cause cell death, and effectively clean biofilms. Therefore, the use of laser cleaning machines can not only avoid chemical cleaning agent residues, but also eliminate microorganisms and bacteria, ensure the hygienic safety of food production, and greatly reduce food safety risks.

At the same time, laser cleaning machines effectively prevent workers from contacting corrosive chemical solvents or inhaling fine particles generated during abrasive grinding, ensuring the health and safety of workers.

4. Save time and labor

When cleaning various equipment such as mixers and ovens, laser cleaning machines do not need to use chemical cleaning agents for pretreatment, cleaning, drying, etc., which saves cleaning time, and when the equipment is large or the number is large, it greatly reduces the labor intensity of workers.

5. Environmental protection

Laser cleaning machines avoid the use of chemical cleaning agents, reduce wastewater discharge, protect the environment, and promote worker health. In addition, if the chemical cleaning agent is not rinsed thoroughly, the solvent residue can easily contaminate the food and affect food safety.

Application of laser cleaning machine in food industry

In all links of the food industry, pollutants such as oil, carbide, gel, oxide, rust, etc. will accumulate during daily production. Laser cleaning machine can efficiently and thoroughly clean the equipment and tools used in food processing, ensuring a non-contact cleaning process, without chemical solvents, and no pollution to the food production environment.

1. Degreasing

Laser cleaning machine can effectively remove grease and oil stains on food processing equipment. In the food industry, most departments will produce oil stains during the production process. Regular cleaning and thorough degreasing are related to the taste and safety of food, and will affect the operation of equipment and safety hazards.

What can laser cleaning machine clean?

Frying equipment: used in fried food industry, catering industry, such as fryers, ventilation ducts, walls, floors, etc.

Dairy equipment: mixers, filling equipment and conveyors required for the production of cream and cheese in the dairy industry.

Baking equipment: ovens, baking trays, pans, molds, etc. commonly used in the baking industry.

2. Remove carbides

During high-temperature cooking and baking of food, organic matter is easily decomposed into black or dark brown residues. These residues
Attach to the surface of the equipment. If they are not thoroughly removed for a long time, they will affect the efficiency and life of the machine and endanger food safety and hygiene. Where do common carbides appear?
Baking industry: Residues of flour, sugar, butter, etc. may carbonize, leaving black carbides on the furnace walls, trays and molds.

Fast food industry: Frequent frying and high-temperature cooking will leave carbides on stoves, grills, ovens and exhaust pipes.

3. Makeup remover gel

During the food production and processing process, if the raw materials contain viscous substances such as sugars, proteins, lipids, thickeners, etc.,
it is easy to accumulate a large amount of viscous substances on the surface of the production equipment or the inner wall of the filling machine. For example, in the beverage and dairy processing industry, the continuous use of filling equipment will form a thick layer of colloid in the pipe.

Laser cleaning machine can completely remove these gel deposits to ensure safe food production and the smooth operation of the entire production line.

4. Remove oxides and rust

In the food industry, liquids and metal equipment are used in almost all links during the production and processing, which can easily lead to the formation of oxides and rust, which not only affect the normal operation and service life of the equipment, but also endanger the quality and safety of food.

For example, factories producing alcohol often use large metal fermentation tanks and storage containers. Due to frequent contact with large amounts of liquids and high humidity during the production process, the metal surface is prone to oxidation and rust.

Laser cleaning technology effectively solves these problems, improves the efficiency of the production line, and ensures the quality and safety of the product.

Summary

As an advanced cleaning technology, laser cleaning equipment adheres to the concept of "machines make work easier" to reduce the labor intensity and safety risks of the food industry. If you are looking for a cleaning solution that can meet thorough, precise and efficient requirements while ensuring environmental responsibility and personnel safety during operation, laser cleaning machine is your ideal choice! 

Understand the forms and applications of laser welding processes：

As a modern high-end welding technology, laser welding has been widely used in many industries due to its advantages of high power density, precise control and non-contact operation. Compared with traditional welding methods, laser welding not only has the characteristics of deep penetration, fast welding speed, small heat-affected zone and less deformation, but also performs particularly well in handling high-precision and high-complexity welding tasks. It is widely used in high-end manufacturing fields such as automobiles, ships, aerospace, electronics, and energy, and has become one of the indispensable technologies in modern manufacturing.

With the rapid development of the global manufacturing industry, the application scenarios of welding technology are becoming increasingly rich, and the welding requirements are becoming higher and higher. Laser welding technology has gradually replaced traditional welding methods in many fields due to its high precision, high efficiency, low pollution and applicability to a variety of materials. Below, we will take a deep look at several common laser welding process forms and their applications.

1. Laser spot welding
Laser spot welding is a welding method that uses a high-energy laser beam to quickly heat the contact points of two workpieces to form a weld. Laser spot welding is mainly divided into two forms: pulsed laser spot welding and continuous laser spot welding.

(1) Pulse laser spot welding: In pulse laser spot welding, the peak energy of the laser beam is high, but the action time is extremely short, which is suitable for welding light metals such as magnesium alloys and aluminum alloys. Its advantage is that it can quickly heat and form a local molten pool, prevent excessive heat input, reduce deformation, and is suitable for precision welding.

(2) Continuous laser spot welding: Unlike pulse laser spot welding, continuous laser spot welding has a higher average power and a longer laser action time, and is usually used for welding steel and other metals. Because it can provide continuous heat input, it is suitable for welding tasks that require greater joint strength.

In the automotive industry, laser spot welding is widely used in car body welding, especially in the connection between aluminum alloys and steel that requires high-quality welding. Due to its non-contact characteristics, laser spot welding can avoid the electrode wear problem caused by traditional resistance spot welding, and the welding trajectory can be flexibly designed according to needs to meet the high-quality welding requirements of automobile body materials under different overlap gaps.

2. Laser vertical welding
Laser vertical welding is a process for placing two parallel workpieces vertically and welding them along the contact line using a laser beam. During the welding process, the laser beam forms a vertical seam by irradiating the workpiece perpendicularly. Vertical laser welding is particularly suitable for butt or overlap connection of thicker plates or pipes.

Common applications include steel structures, bridges, ships and other fields. In these fields, the thickness and strength of the welded joints are required to be high. Traditional welding methods may cause large heat-affected zones and welding deformation, while the high-energy beam of vertical laser welding can achieve more precise heat input, reduce deformation, and improve welding efficiency.

3. Laser welding
Laser welding refers to the butt jointing of multiple workpieces in a certain arrangement, usually edge butt jointing or edge overlap, and then scanning or spot welding along the edge with a laser beam to form a seam parallel to the surface of the workpiece.

This process is suitable for connecting thin plates or films of the same or different materials, and is widely used in electronic products, circuit boards, solar cells, display screens and other fields.

For example, in the manufacturing process of solar cells, laser welding can accurately connect multiple cells to avoid material damage or poor contact problems that may occur in traditional welding. At the same time, welding can also ensure high welding speed and joint strength to meet the needs of large-scale production.

4. Laser stitch welding
Laser stitch welding refers to stacking multiple workpieces on the same plane in a certain order, and welding along the overlapping area with a laser beam to form a seam parallel to the surface of the workpiece. Stitch welding is usually used to connect thicker materials, such as automotive parts, aircraft structural parts, chemical equipment, etc.

The advantage of laser stitch welding is that its efficient and precise welding method can tightly connect different materials or materials of different thicknesses to form high-strength joints. Due to the high power density of the laser, it can effectively reduce heat input, control the heat-affected zone, and avoid excessive deformation and cracks in the traditional welding process. For high-demand parts and structural parts, laser stitch welding provides a more precise and reliable welding solution.

Application prospects of laser welding
With the continuous development and progress of laser technology, the application prospects of laser welding are broader, especially in the fields of lithium battery manufacturing, rail transportation, automobile manufacturing, shipbuilding, etc. Laser welding has become one of the indispensable core technologies in these industries.

1.In lithium battery manufacturing, laser welding can accurately connect battery modules to ensure high efficiency and high safety.

2.In the rail transit industry, laser welding is widely used in the connection of rails and the welding of car body structures, which can effectively improve production efficiency and ensure the quality of connection.

3.In automobile manufacturing, laser welding not only improves production speed, but also realizes the precise connection of different materials, effectively reducing the quality of vehicles.

4. In shipbuilding, laser welding technology can ensure the welding quality of hull structures and reduce deformation and residual stress generated during welding.

In short, laser welding technology is gaining more and more widespread applications in all walks of life due to its advantages in precision, speed, energy saving and environmental protection, and with the continuous innovation and development of technology, laser welding will continue to contribute to the intelligent and precise development of the manufacturing industry. 

Learn about the forms and applications of laser welding processes:

As a modern welding technology, laser welding has the advantages of deep melting, fast speed, small deformation, high power density, and no influence of magnetic field. It is widely used in high-end precision manufacturing fields such as automobiles, ships, and aerospace.

With the rapid development of the manufacturing industry, welding technology is more and more widely used, and the level of welding technology is also getting higher and higher. Let's learn about different welding forms and their applications.

1. Laser spot welding

There are two main forms of laser spot welding: pulse laser spot welding and continuous laser spot welding. The laser beam peak energy in pulse laser spot welding is high, but the action time is short. It is generally used for welding light metals such as magnesium alloys and aluminum alloys; the laser beam in continuous laser spot welding has high average power and long laser action time, and is mostly used for welding steel.

In terms of automobile body welding, compared with resistance spot welding, laser spot welding has the advantages of non-contact and self-designed spot welding trajectory, which can meet the high-quality welding requirements of automobile body materials under different overlap gaps.

2. Laser vertical welding

Vertical welding refers to placing two parallel workpieces vertically with their end faces facing each other, and then welding along the contact line of the end faces with a laser beam to form a vertical seam perpendicular to the surface of the workpiece. Vertical welding is suitable for butt or overlap connection of thicker plates or pipes, such as steel structures, bridges, ships, etc.

3. Laser welding

Welding refers to arranging two or more workpieces on the same plane according to a certain pattern, so that their edges are adjacent or overlapping, and then scanning or spot welding along the edges with a laser beam to form a seam parallel to the surface of the workpiece.
Welding can achieve connections in various patterns and forms, such as grids, stripes, waves, etc., and is suitable for connecting thin plates or films of the same or different materials, such as circuit boards, solar cells, display screens, etc.

4. Laser stack welding

Stack welding refers to stacking two or more workpieces on the same plane in a certain order, so that they partially overlap or completely overlap, and then scanning or spot welding along the overlapping area with a laser beam to form a seam parallel to the surface of the workpiece.

Stack welding is suitable for connecting thick plates or pipes of the same or different materials, such as automotive parts, aircraft structural parts, chemical equipment, etc.

With the increasing popularity of laser welding in many industries, especially in lithium battery manufacturing, automobile manufacturing, rail transportation, ship manufacturing and other industries, laser welding, as an important link in the manufacturing process, has ushered in a new development opportunity. 

Innovative Application of Laser Cleaning in Emerging Industries:

As an efficient and environmentally friendly surface treatment technology, laser cleaning technology is showing its unique advantages and application potential in more and more emerging industries. In recent years, it has been innovatively applied in emerging industries such as new energy vehicles, 3D printing, aerospace, and cultural relics protection.

New Energy Vehicle Industry

In the field of new energy vehicles, laser cleaning technology is becoming one of the key technologies for battery manufacturing and electric vehicle maintenance. The core component of new energy vehicles, power batteries, requires strict control of the presence of impurities and pollutants during its manufacturing process to ensure the performance and safety of the battery. Laser cleaning technology can efficiently remove oil stains, metal debris and other pollutants on the surface of battery poles, shells and other components, improve the cleanliness and consistency of the battery, and thus improve the energy density and cycle life of the battery. In addition, during the repair and maintenance of electric vehicles, laser cleaning technology can also be used to remove dirt and carbon deposits on the surface of components such as motors and controllers, and improve heat dissipation performance and operating efficiency.

3D Printing Industry

As a revolutionary breakthrough in the manufacturing industry, 3D printing technology is being applied in more and more fields. However, the removal of powder residues and support structures generated during 3D printing has always been one of the bottlenecks restricting its development. Laser cleaning technology can accurately remove powder residues and support structures on the surface of 3D printed parts without causing damage to the printed parts themselves, thus improving the accuracy and surface quality of the printed parts. In addition, laser cleaning can also be used for the pretreatment of 3D printed materials, removing oxides and contaminants on the surface of materials, and improving the bonding strength and performance of printed parts.

Aerospace industry

The aerospace field has extremely high requirements for the high performance and cleanliness of materials. Laser cleaning technology can efficiently remove oil, rust, coating and other contaminants on the surfaces and parts of aircraft, rockets and other aerospace vehicles, improve the cleanliness and accuracy of the surface, and ensure the safety and stability of flight. In addition, laser cleaning can also be used for the repair and maintenance of aerospace vehicles, remove surface damage and corrosion, and extend the service life. In the manufacturing process of aerospace vehicles, laser cleaning technology can also be used to remove spatter and burrs generated by welding, cutting and other processes, and improve manufacturing quality and efficiency.

Cultural relics protection industry

Cultural relics protection is an important task in inheriting historical culture. Traditional cultural relics protection methods often have problems such as complex operation, low efficiency, and easy damage to cultural relics. Laser cleaning technology, with its non-contact, high precision and environmental protection characteristics, has shown great application potential in the field of cultural relics protection. Laser cleaning can accurately remove pollutants such as dirt, rust and coating on the surface of cultural relics without damaging the cultural relics themselves, preserving the original appearance and historical information of the cultural relics. In addition, laser cleaning can also be used for the repair and reinforcement of cultural relics to improve the stability and durability of cultural relics.

With the continuous advancement of technology and the reduction of costs, the innovative application of laser cleaning technology in emerging industries has not only improved production efficiency and quality, but also promoted the sustainable development of related industries. 

Application of pulse laser cleaning technology in lithium battery cleaning

Currently, in the new energy battery industry, laser cleaning technology has seen extensive applications in lithium battery cleaning. It not only improves cleaning efficiency and quality but also reduces production costs and environmental pollution. With ongoing technological advancements and decreasing costs, laser cleaning technology is expected to be more widely applied in lithium batteries and other industrial sectors, contributing to the promotion of green manufacturing and sustainable development.

1.Laser Cleaning Before Electrode Coating

The positive and negative electrode sheets of lithium batteries are coated with lithium battery materials on metal foils, typically aluminum or copper. Before applying the electrode materials, the metal foils need to be cleaned to ensure the adhesion of the coating and the battery's performance. Traditional wet ethanol cleaning methods can easily damage other components of the lithium battery, while laser cleaning technology effectively addresses this issue. By using pulsed lasers to directly irradiate and remove contaminants, the surface temperature of the metal foils increases, causing the pollutants to vibrate due to thermal expansion, ultimately overcoming the surface adhesion and detaching from the substrate. This achieves a damage-free cleaning process.

2.Laser Cleaning Before Battery Welding

Welding is a critical step in the production of lithium batteries. A clean and uniform surface is essential for achieving durable and successful welding and bonding. Therefore, prior to welding, surface treatment is required to remove contaminants at the weld joints. Laser cleaning technology can efficiently and precisely remove dirt and dust from areas such as the sealing pins, connection plates of the cell segments, as well as the busbars, single cell blue membranes, silicone, and coatings, preparing for the welding process and reducing the occurrence of defective welds.

3.Laser Cleaning During Battery Assembly

During the battery assembly process, to prevent safety incidents with lithium batteries, external adhesive treatment is typically required for the cell to provide insulation, prevent short circuits, and protect the circuitry from scratches. Laser cleaning of the insulation boards and end plates can clean the surfaces of the cells, roughen the surfaces, and enhance the adhesion of adhesives or coatings. Laser cleaning generates no harmful pollutants, making it an environmentally friendly cleaning method that meets current societal demands for environmental protection. 

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Characteristics of wire feeding in laser wire welding：

Laser welding concentrates energy in a small range, instantly melts the welding wire and the base material to form a weld. Therefore, the welding depth after welding is large, the weld is narrow, and the speed is fast. It is suitable for self-melting welding, and usually no welding wire is needed. Of course, laser welding machines can also perform wire welding. Generally, welding wire needs to be added when the weld is larger than 1mm.

The filling of welding wire makes the laser welding process more complicated. Mastering the wire feeding characteristics of laser wire welding under different welding conditions is a prerequisite for obtaining high-quality welds.

Wire feeding speed is an important process parameter for laser wire welding. Reasonable selection of wire feeding speed can make full use of laser energy and improve production efficiency. The wire speed should be determined according to the gap amount of the joint. During laser welding, the welding wire is almost 100% transferred to the welding pool. Therefore, the wire feeding speed can be calculated based on the material balance of the welding process. The excess height of the weld section and the gap of the joint are both filled with welding wire.

According to different welding processes, the welding wire can be fed from the front of the laser or from the back, and at a certain angle to the optical axis. In laser wire welding, the welding wire is generally required to be coplanar with the weld on the vertical plane, so that when there is a slight fluctuation in the wire feeding process, the stable transition of the molten droplet can be guaranteed. The straightness of the welding wire is very important for the stability of welding, affecting the absorption of the beam energy by the welding wire and the stability of the welding process. In order to ensure that the welding wire is delivered to the intersection of the optical axis and the base material, a copper tube is generally used to guide the welding wire at the end of the wire feeding hose, as shown in the figure. A gas pipe is installed above the workpiece to blow helium or argon gas on the side to protect the molten pool and suppress plasma. For some metals that are easily oxidized (such as titanium alloys), a special protective cover is also required to protect the molten pool and the high temperature area of ​​the weld.

Generally, the wire feeding angle is more suitable between 30° and 75°. The wire feeding position should be aligned with the center line of the weld as much as possible. When the wire feeding position deviates from the center line of the weld by 0.25mm, the melting efficiency of the 2mm welding wire will be reduced by 30%, and the melting efficiency of the 1.0mm and 1.2mm welding wires will be reduced by about 36%. Therefore, in the case of high welding requirements, the best method is to equip an optical weld tracking system for real-time monitoring and control of the welding wire position.

If the wire feeding speed is too fast or too slow, it will cause the accumulation or lack of wire droplets in the transition to the molten pool, and will also affect the interaction between the laser and the welding wire and the base material, thereby affecting the formation of the weld. The commonly used wire feeding mechanism needs to have a feedback system that can keep the set wire feeding speed unchanged during the welding process. The figure shows the composition of the laser wire welding system. In the high-precision welding process, the metal filling amount is required to be adjusted in real time according to the changes in the weld groove to ensure a stable and accurate filling amount to obtain good weld formation. 

The best solution is to equip a set of wire feeding control systems that can dynamically follow the changes in the weld groove.

Most laser wire welding uses cold wire. When the welding wire is not heated, a large part of the energy of the laser beam acts on the welding wire, which will undoubtedly reduce the welding speed. In order to make full use of the laser energy, the hot wire welding process can be introduced. Hot wire welding reduces the energy consumed by the laser on the welding wire and effectively increases the welding speed. The laser hot wire welding process requires an additional set of preheating equipment, generally using resistance heating. The electrode can be directly connected to the wire feeding roller, and the welding wire is instantly heated to a temperature close to the melting point through a large current. When the welding wire is sent to the edge of the welding pool, due to the high surface temperature of the welding wire, only a small amount of laser energy is needed to melt it. The molten welding wire can absorb a large amount of laser energy and conduct it to the parent material. Compared with self-melting welding, hot wire welding is more conducive to the absorption of laser energy. Therefore, the welding speed of laser hot wire welding can be higher than that of self-melting welding. In order to avoid oxidation of the welding wire metal, the heated welding wire part is only 3~5mm away from the intersection of the laser beam and the welding wire, which can avoid excessive temperature reduction of the heated welding wire. When using laser hot wire welding, there should be enough distance between the focusing lens and the workpiece to be welded for installing the heating device, and it is advisable to use a lens with a larger focal length. Although the focal spot diameter increases with the increase of focal length, which reduces the power density and is not conducive to energy absorption, increasing the focal length can increase the focal depth, which is more beneficial for thick plate welding. 

Common problems and solutions of laser welding of aluminum alloys:

Before discussing the technical details of laser welding of aluminum and aluminum alloys, we need to understand the basic working principle of laser welding machines. Laser welding machines use high-intensity laser beams to locally heat the welding area to a molten state to achieve precise metal connections. Its main components include lasers, optical systems, and welding heads. The laser generates high-energy lasers, the optical system focuses the laser beam to the welding site, and the welding head ensures the accurate positioning of the laser beam. Laser welding machines can provide a concentrated and high-power heat source, reduce the heat-affected zone and deformation, and thus improve welding quality and efficiency. Especially when welding aluminum, the precise control function of these devices can effectively deal with common problems in aluminum welding, such as pores and cracking. Modern laser welding machines are also equipped with intelligent control systems that can adjust process parameters in real time to ensure the stability and consistency of the welding process.

Aluminum and aluminum alloys are widely used in construction, transportation, automobiles, electronics, packaging, and aerospace due to their light weight, high strength, and corrosion resistance. With the development of technology, the aluminum alloy welding process has been improved. Laser welding is a welding technology commonly used in the market. It has the advantages of high-power heat source concentration, small heat-affected zone, less deformation, energy saving and consumption reduction.

In the daily welding process, due to the special properties of aluminum, it is difficult to control the laser focus and molten pool when laser welding aluminum and aluminum alloys; when the welder sets the process parameters improperly or lacks rich experience, problems such as pores, cracking and deformation, blackening of welds and non-fusion of undercuts may occur, which seriously affect the welding quality and performance. Next, we will introduce the difficulties and solutions encountered in welding aluminum.

The main problem encountered when using laser welding aluminum is pores. During the welding process, the laser beam causes the molten pool metal to fluctuate. When the gas trapped in the metal expands and overflows, pores will appear; in addition, the aluminum oxide film will hinder the bonding between metals, absorb moisture and easily produce impurities, which will promote the formation of pores.

The generation of pores will lead to weaker weld strength, reduced corrosion resistance, and unsightly welds. In general, the following measures are recommended:

Adjust the appropriate laser power to ensure uniform heat input.

When welding thin plates, it is recommended to increase the speed to reduce the time for gas to expand in the metal; when welding thick plates, the welding speed can be reduced to ensure performance when the material is preheated.

Chemically or mechanically clean the weld surface to reduce the impact of impurities on the welding quality.

Control the use of shielding gas or flux to reduce oxidation and reduce the amount of gas formed.

Due to the high temperature generated during welding, aluminum will expand and contract rapidly and produce stress points. If the weld solidification interval is too short and the stress points are not released, they will cause aluminum to crack and thermal cracks to appear; in addition, oxidation and thermal cracks will easily occur when the weld protection effect is not good.

To avoid this situation, we need to control the heat during welding, fully preheat the weldment before welding, and adjust the shielding gas.

The blackening of aluminum in laser welding is mainly caused by insufficient laser power, the focal length is not adjusted to the appropriate value, or the laser lens is damaged. In this case, the energy of the laser fails to reach the melting threshold of the oxide layer on the surface of the aluminum material, causing the aluminum to mix with air and impurities, resulting in blackening of the welded part.

In order to better obtain the quality and aesthetics of welding, during the aluminum welding process, PES LASER recommends first selecting the appropriate power and adjusting the correct focal length; secondly, you can also check whether the protective lens is damaged.

When laser welding aluminum, discontinuous, rough and uneven welds are a typical phenomenon. The main reasons are too large assembly gap of welds, laser spot offset, insufficient laser power and excessive defocus.

First, we can reduce the root gap of the welded workpiece: second, adjust the focus of the laser beam to determine the correct spot position; in addition, we can also ensure the welding quality after aluminum melting by increasing the laser power and adjusting the correct focal length.

Due to the particularity of aluminum, other problems will also be encountered during laser welding. Before welding aluminum and aluminum alloys, we must not only consider the stability of welding quality, but also the appearance of welding. With the improvement of laser technology and aluminum manufacturing technology, the process of laser welding aluminum has also been greatly improved, providing a solid foundation for creating lightweight metal structural components in the fields of automobiles, aerospace, etc. 

Laser high temperature use reminder:

With the arrival of high temperature and high humidity weather, lasers have encountered severe challenges in daily operation. This article will analyze in detail the impact of environmental control on lasers, the principle of condensation, and how to effectively prevent and deal with these challenges.

How does condensation occur on lasers?

Condensation is the phenomenon that when water vapor in the air encounters a cold surface, the temperature drops below the dew point and the water vapor condenses into liquid water. In lasers, lasers are usually equipped with a cooling system to maintain their internal temperature stability. The cooling system takes away the heat generated by the laser by circulating coolant.

However, when the ambient temperature and humidity are too high, the cooling system may cause the surface temperature of the laser to be lower than the dew point temperature of the surrounding air. The surface will condense the moisture in the air and attach it to the laser, and condensation will occur.

What are the effects of condensation on lasers in a hot and humid environment?

1. Aging of internal components of the laser

High temperature will accelerate the aging process of internal components of the laser, especially electronic components. The performance degradation of aging components may cause the laser to work unstably or even fail.

2. Condensation can cause a short circuit in the laser circuit
Once condensation occurs on the surface of the circuit board and electrical module inside the laser, condensed water may cause a short circuit in the circuit board device, damage sensitive electronic components, and even cause the entire laser to fail and be scrapped.

3. Optical performance degradation, power, and spot problems
After condensation occurs on the optical device, the water droplets formed on the surface will affect the reflection and refraction of light, causing changes in the output power and spot pattern of the laser. In addition, water droplets may also corrode the optical lens, further reducing the performance of the laser.

How to prevent laser condensation?

1. Ambient temperature and humidity control
By controlling the temperature and humidity of the environment where the laser is located, condensation can be effectively prevented. This includes using an air conditioning system to lower the ambient temperature and using a dehumidifier to control the ambient humidity.

2. Cooling system setting
According to the changes in ambient temperature and humidity, reasonably adjust the set temperature of the laser cooling system to ensure that the temperature of the cooling water is higher than the dew point temperature of the environment to avoid condensation due to excessive temperature difference.

3. Application of temperature and humidity dew point comparison table
Using the temperature and humidity dew point comparison table, we can intuitively understand the dew point temperature under different environmental conditions, so as to set the temperature of the cooling system more accurately and avoid condensation.

Through the above measures, we can ensure the stable operation of the laser in a high temperature and high humidity environment, extend the basic service life, and maintain the best working performance. As engineers, we should pay close attention to environmental changes and adjust equipment parameters in time to ensure the efficient and safe operation of the laser.