Aluminum welding
Aluminum welding using laser technology is particularly important in the production of cooling elements for e-mobility. BLS is regarded as a pioneer in application development, not least due to its technical equipment specially designed for aluminum welding.
BLS advantages in aluminum welding
Especially for aluminum welding (Alu, Al) or copper (Cu), powerful lasers, specific laser equipment such as special optics and many years of experience in parameter determination are indispensable prerequisites. BLS Lasertechnology GmbH supports you with extensive laser know-how from parameter determination and basic development to prototype production and series production. Our laser specialists and welding engineers ensure optimum overall results, both in application development and prototype construction as well as in series production.
Aluminum laser welding
For BLS customers, the processing of aluminum components is currently becoming an increasingly important area of application for laser technology, particularly in the context of e-mobility. In terms of the welding process, aluminum differs from other metals (such as steel, iron or copper) due to specific material properties, such as the material’s high thermal conductivity and high reflectivity, which can pose a challenge when coupling the laser beam during laser welding. Solid-state lasers such as Nd:YAG lasers or modern fiber lasers are suitable for aluminum welding because their wavelengths can be absorbed well by the aluminum material. Due to its low weight, aluminum is ideal for large cooling systems, e.g. in e-mobility for cooling battery systems.
Success factors in aluminum welding
The laser welding of aluminum components requires a process technology adapted to the material. Depending on the condition of the material, it may be necessary to thoroughly prepare the surfaces of the workpieces before aluminum welding, either by brushing, milling and grinding or by chemically removing (pickling) the oxide layer.
Furthermore, aluminum welding requires the use of shielding gases such as helium or argon to prevent rapid oxidation during the welding process. The optimum process parameters for aluminum welding must be determined and adjusted in advance. In particular, the use of special optics is a success factor for high seam quality and tightness of the weld seam. BLS works here with the latest technology from Trumpf. So-called multipost optics allow the laser beam to be divided into up to four focal points. This innovative technology makes it possible to widen the weld pool and thus the weld seam, while at the same time minimizing the formation of pores to ensure that the weld seam is gas-tight, for example. At BLS, we also use the Brightline Weld beam shaping technology from Trumpf. Our success factors in aluminum welding:
- High-performance machinery
- Specific laser equipment for aluminum welding (e.g. multi-spot optics and Brightline Weld beam shaping from Trumpf)
- Highest level of quality thanks to highly qualified laser and materials experts
- Various options for leak tests (e.g. helium leak test)
Laser welding process: Aluminum welding with laser technology
Pulse welding
Short laser pulses create spot weld seams. This process is suitable for thin materials, such as aluminum sheets, or for very precise applications.
Continuous wave welding
(“Continuous Wave”, CW)
In this process, a continuous laser beam ensures continuous weld seams. This means that thicker components in particular can also be welded.
Heat conduction welding
At a lower intensity, the metal is melted by heat conduction, producing particularly smooth weld seams.
Deep welding
At a lower intensity, the metal is melted by heat conduction, producing particularly smooth weld seams.
Laser welding:
Aluminum laser welding in comparison
Aluminum is characterized by high surface reflection and high thermal conductivity. This makes it more difficult to absorb energy during laser welding and processing requires a higher laser power than with other metals such as steel or iron.
Copper is also characterized by its high thermal conductivity and surface reflection. Another special feature of copper is its electrical conductivity. Welding copper with a laser generally requires a higher laser power than aluminum welding.
Advantages of laser welding for aluminum
- Laser welding from prototypes (sample production) to series production
- Support in the design of the component for an optimum welding result
- Cleaning of components using our own industrial cleaning system
- Fixture construction and clamping systems
Suitable aluminum alloys for laser welding
Most aluminum alloys are basically laser-weldable. The wrought aluminum alloys adapted to the respective requirements are divided into series from 1. to 8. according to DIN EN 573-3. Even small additions of the alloying elements magnesium, silicon, copper, zinc, nickel and manganese greatly change the properties of pure aluminum.
The alloys of the 5th series (AlMg) and the 6th series (AlMgSi) are particularly suitable for laser welding. The high-silicon aluminum alloys from series 4 can also be welded well using laser technology, as silicon reduces the formation of cracks.
Of the hardenable materials in series 7, only the copper-free representatives of the AlZnMg type can be used for laser welding.
Various welding processes for aluminum components
Solid-state lasers are particularly suitable for aluminum materials due to their high absorption rate. Both fiber and YAG lasers enable deep penetration welding, in which the laser beam penetrates deep into the material and deep weld seams can be created when welding aluminium.
The highest energy densities are generally achieved with laser and electron beam welding. Very high welding speeds and very narrow weld seams are possible with these two welding processes. The fact that only narrow heat-affected zones occur here has a positive effect on the residual stress and distortion of the processed component. The advantage of laser beam welding compared to electron beam welding is that no vacuum situation needs to be created during laser welding, which means that significantly shorter cycle times are possible in series production.
For laser welding with filler material (also known as laser metal deposition), welding rods or filler powders made of similar alloys to the base material are generally used to ensure the best possible compatibility. Argon or an argon-helium mixture is used as the shielding gas to prevent oxidation and control the formation of plasma above the molten metal.
Advantages of laser welding technology
for aluminum & other metals
Laser technology can be used for joining metals such as copper, aluminum, iron, titanium or steel as well as for complex component shapes (2D/3D geometries). The laser ensures very high efficiency and consistently high quality during (serial) processing. Due to the automated guidance of the laser beam, there is no alternative to the precision of the process and the repeat accuracy. Smooth, clean weld seams allow the components to be used in the visible area. In aluminum welding, the tightness of the weld seam is also of great importance in many areas of application.
We are happy to advise you at!
BLS Lasertechnology GmbH has all common laser welding processes at its disposal. We will be happy to advise you on the selection of the right process, taking into account the requirements of the weld seam and the component to be processed. The focus is always on quality and an optimum result. Contact us and together we will find a solution to your problem!
Aluminum welding, equipment and laser technology
The equipment for aluminum welding includes the laser source, an optical system for beam guidance and beam focusing, the necessary clamping device for fixing the components, an automatic CNC control for moving the laser optics (or the component) as well as the shielding gas supply, an extraction system and protective devices or shielding screens in accordance with occupational health and safety regulations.
- The laser source for aluminum welding is usually a solid-state laser (e.g. YAG laser) or a gas laser (e.g. CO2 laser) with high beam quality and power.
- A beam guidance system consisting of mirrors or fiber optic cables guides the laser beam to the processing point during aluminum welding.
- Focusing optics consisting of lenses and/or mirrors focus the laser beam to the desired size and intensity.
- The laser setup includes a clamping device that holds the components precisely in position or, if necessary, moves them according to the CNC program. Alternatively, the flying optics can be moved “on the fly” in three-dimensional space using CNC control. The clamping fixtures are designed and produced in BLS's own fixture construction department
Challenges with aluminum welding and remedies
Thick material thicknesses
Thick materials are more difficult to process than thin ones when welding aluminum. The risk of distortion increases with higher energy input.
Remedy:
The laser set-up and parameters must be individually adapted to the application. BLS Lasertechnology GmbH also enables the processing of particularly thick materials through the use of high-power lasers in combination with special optics and beam shaping technology.
Pore formation and low seam quality
Common problems in aluminium welding are unevenness in the weld pool and the resulting pore formation, ejections, cracks and insufficient seam strength.
Remedy:
These defects in aluminium welding can be counteracted by optimized process parameters, thermal treatment of the material, use of shielding gases and adapted feed rates as well as special optics and special beam shaping technology
Very thin material thicknesses
With very thin material thicknesses, there is a risk of burn-through when welding aluminum.
Remedy:
The laser set-up and parameters must be individually adjusted to the application.
Impurities
The welding process often results in contamination during aluminum welding
Remedy:
Laser welding seams can be refined by mechanical post-processing such as grinding or polishing.
