Analysis of the five major application markets of fiber laser welding

Laser welding is one of the earliest applications in industrial laser material processing. In most early applications, the weld seams produced by lasers were of higher quality, thereby increasing productivity. With the development of laser types, laser sources now have higher power, different wavelengths and a wider range of pulse capabilities. In addition, beam transmission, machine control hardware and software, and process sensors all promote better new developments in the laser welding process.

Laser welding has unique advantages, including low heat input, narrow fusion zone and heat-affected zone, and excellent mechanical properties of materials that were previously difficult to weld using a process that would generate greater heat input to the part. These properties make the weld formed by laser welding stronger and more attractive in appearance. In addition, the setup time required for laser welding is also much less. With the addition of laser tracking sensors, automation can be achieved, thereby reducing product costs. All these new technologies have further expanded the application range of laser welding. In many industries, fiber laser welding using different metals, component shapes, sizes and volumes has been successfully applied.

1. Battery welding

The increasing application of lithium batteries in electric vehicles and many electronic devices means that engineers use fiber laser welding in product design. The current-carrying components produced by copper or aluminum alloy are connected to terminals by fiber laser welding to connect a series of batteries in the battery. Laser welding aluminum alloy (usually 3000 series) and pure copper to form electrical contact with the positive and negative electrodes of the battery. All materials and material combinations used in the battery are candidates for the new fiber laser welding process. Overlapping, butting and fillet welding joints make various connections inside the battery. Laser welding of the lug material to the negative and positive terminals creates electrical contact with the package. The final battery assembly welding step, which is the sealing of the joints of the aluminum can, creates a barrier for the internal electrolyte. Since the battery is expected to work reliably for 10 years or more, laser welding can always be of high quality. Using the correct fiber laser welding equipment and technology, laser welding can consistently produce high-quality welds of 3000 series aluminum alloys.

2. Precision machining and welding

Seals used in ships and chemical refineries, as well as in the pharmaceutical industry, were originally TIG welded. Because they are used in sensitive environments, these components are precision machined and ground from high-temperature and chemical-resistant nickel-based alloy materials. The batch is usually small and the number of settings is large. It is understood that at present, the assembly of these components has been improved using fiber laser welding. Reasons for replacing the earlier robotic arc welding process with fiber laser welding include: consistent laser welding quality; easy conversion from one component configuration to another, thereby reducing setup time and increasing output; and tracking through assembly lasers Sensors automate the laser welding process to reduce costs.

3. Airtight welding

Hermetically sealed electronics in medical devices (such as pacemakers and other electronics) have made fiber laser welding the process of choice for applications requiring the highest reliability. The latest developments in air-tight welding process have solved the problems related to laser welding and weld end point, which is the key position to complete the air-tight seal. In the previous laser welding technology, when the laser beam is turned off, even when the laser power is reduced, a dent will be generated at the end point. Advanced laser beam control eliminates dents in thin welds and deep welds. The result is consistent weld quality, no porosity at the end, and improved appearance and more reliable sealing.

4. Aerospace welding

Fiber laser welding of nickel and titanium-based aerospace alloys requires control of weld geometry and weld microstructure, including minimizing porosity and controlling grain size. In many aerospace applications, the fatigue performance of welds is a key design criterion. Therefore, design engineers almost always specify that the welding surface is convex or slightly convex to enhance the welding strength. To this end, filling lines with a diameter of 1.2 mm are used for automated processes. Adding filler wire to the butt joint will result in consistent weld crowns on the top and bottom bead. By ensuring a good microstructure of the weld, the choice of wire alloy also contributes to the mechanical properties of the weld.

5. Dissimilar metal welding

The ability to use different metals and alloys to make products has greatly increased the flexibility of design and production. While controlling costs, optimizing the performance of the finished product, such as corrosion, wear and heat resistance, is a common motivation for welding dissimilar metals. Connecting stainless steel and galvanized steel is an example. Due to its excellent corrosion resistance, 304 stainless steel and galvanized carbon steel have been widely used in various applications, such as kitchen appliances and aviation components. This process presents some special challenges, especially because zinc coatings can cause serious weld porosity problems. During the welding process, the energy to melt steel and stainless steel will evaporate zinc at about 900 degrees Celsius, which is much lower than the melting point of stainless steel. The low boiling point of zinc leads to the formation of steam during keyhole welding. When trying to escape the molten metal, zinc vapor may be trapped in the solidified weld, resulting in excessive weld porosity. In some cases, zinc vapor will escape as the metal solidifies, thereby forming pores or roughness on the welding surface. With proper joint design and selection of laser process parameters, finishing and mechanical welding can be carried out easily. There are no cracks or pores on the upper and lower surfaces of the lap welds of 304 stainless steel with a thickness of 0.6 mm and galvanized steel with a thickness of 0.5 mm.