Laser welding is one of the first and most significant applications in industrial laser material processing.
In early applications, laser-generated welds were of superior quality, leading to greater productivity.
Over time, advances in laser technology have led to higher power lasers, a wider range of wavelengths, and improved pulse capabilities. Furthermore, advances in beam propagation, machine control hardware and software, and process sensors have contributed to the continued development of laser welding processes.
Laser welding offers several unique advantages, including low heat input, a narrow fusion zone and a heat-affected zone, and excellent mechanical properties for materials that were previously difficult to use in processes that produce large heat inputs to parts. . These properties make laser welding an attractive option for producing strong, visually appealing welds.
Additionally, the setup time required for laser welding is much shorter and when combined with laser tracking sensors, automation can be achieved resulting in lower production costs.
All these new technologies have expanded the range of applications of laser welding. In many industries, fiber laser welding has been used successfully with different metals, shapes, sizes and volumes of components.
1. Battery welding
The increased use of lithium batteries in electric vehicles and electronic devices has led engineers to incorporate fiber laser welding into product design.
Optical fiber laser welding is used to connect the current-carrying components, made of copper or aluminum alloy, to the device's series of batteries.
The electrical contacts with the battery's positive and negative electrodes are formed by laser welding of aluminum alloy, typically 3000 series, and pure copper.
All materials and combinations used in the battery are suitable for the new fiber laser welding process.
Various connections within the battery are created using lap, butt, and fillet welded joints.
Laser welding of terminal material to the negative and positive terminals produces encapsulated electrical contact.
The final step in the battery assembly and soldering process involves sealing the aluminum tank gasket, which creates a barrier to the internal electrolyte.
As the battery is expected to function reliably for a period of 10 years or more, the selection of laser welding ensures high quality and consistency.
Using appropriate fiber optic laser welding equipment and process, high-quality 3000 series aluminum alloy welds can be produced consistently.
2. Precision machining welding
Seals used on ships, chemical refineries and in the pharmaceutical industry were originally TIG welded. Due to their use in sensitive environments, these components are precision machined and ground using nickel-based alloy materials with high temperature and chemical corrosion resistance. Typically, the batch size is small and the number of configurations is large.
Currently, the assembly of these components has been improved through fiber optic laser welding. The reasons for using fiber laser welding to replace the initial robotic arc welding process are as follows:
- Laser welding produces consistent quality.
- It is easy to switch from one component configuration to another, thus reducing setup time and improving production.
- Mounting the laser tracking sensor to automate the laser welding process reduces costs.
3. Gas-tight welding
Fiber laser welding has become the preferred process for medical devices such as pacemakers and other electronics due to the high reliability provided by hermetically sealed electronics.
The latest development of gas-tight welding processes has addressed the problems associated with laser welding and the weld end point, which is critical to achieving a gas-tight seal.
In previous laser welding technologies, the laser beam created depressions at the end point, even when the power was reduced and the beam was turned off.
However, with advanced laser beam control, these depressions can be eliminated, resulting in consistent weld quality, improved appearance and a more reliable seal. This is particularly important for thin, deep welds where porosity at the end point can be a significant problem.
4. Aerospace welding
Controlling weld geometry and microstructure, minimizing porosity, and controlling grain size are essential in fiber laser welding of nickel- and titanium-based aviation alloys. In many aerospace applications, the main design criterion for welds is their fatigue performance.
To increase welding strength, design engineers almost always specify a convex or slightly convex welding surface. To achieve this, an automated process uses a filling line with a diameter of 1.2 mm. Adding filler wire to the butt joint ensures consistent weld crowns on the top and bottom passes.
In addition to ensuring a good microstructure of the weld, the selection of the welding wire alloy also contributes to the mechanical properties of the weld.
5. Welding of dissimilar metals
The ability to manufacture products using different metals and alloys greatly improves design and production flexibility.
Optimizing finished product properties such as corrosion, wear and heat resistance while controlling costs is a common motivation for welding dissimilar metals. The connection of stainless steel and galvanized steel is an excellent example.
304 stainless steel and galvanized carbon steel are widely used in various applications such as kitchen appliances and aviation components due to their excellent corrosion resistance.
However, welding dissimilar metals presents some unique challenges, especially due to the potential for zinc coating to cause severe weld porosity issues.
During welding, the energy used to melt steel and stainless steel will evaporate zinc at about 900℃, 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.
As zinc vapor attempts to escape the molten metal, it can remain in the solidified weld, resulting in excessive porosity. Additionally, zinc vapor may escape during metal solidification, causing pores or roughness on the surface.
Proper joint design and selection of laser process parameters can simplify finishing and mechanical welding.
For example, lap welds of 0.6mm 304 stainless steel and 0.5mm galvanized steel have no cracks or pores on the top and bottom surfaces.
