Solving Cracking, Porosity and More in Laser Welding
This blog was written in conjunction with Florian Hugger from BBW Lasertechnik, the leading innovative laser material processing experts
Automotive manufacturers use laser welding on a daily basis to create integral vehicle parts that must pass rigorous safety standards.
Laser welding has proven to be very powerful in steelwork. However, as the automotive industry shifts to e-mobility, automotive parts use much more copper and aluminum for the required electronic components. The increased thermal conductivity and low absorption of those materials leads to distortions and defects in the final weld.
Here are 5 main challenges in the automotive parts laser welding:
- Cracking in Metals
- High-Speed Welding
- Dissimilar Metals
- Asymmetric Parts
- Laser Welding with Dynamic Beam Lasers
Cracking in Metals
Especially when welding aluminium alloys and high-carbon steels, cracking is a common defect that renders parts unusable.
Hot and cold cracks are formed when the laser makes the parts pull apart by thermal shrinkage, so what’s needed is a laser on either side of the weld in order to push the parts back together to counteract the shrinkage that would cause cracking.
The current solution is to induce a second heat field, by using either an additional laser or via induction heating.
When welding two pieces of different thicknesses (such as one machined part that is thick and one thin sheet metal), an asymmetric heat field is needed. Because such a thing does not exist, the solution is to use the amount of heat required for the thick part despite the fact that it is too much for the thin piece.
The problem with this is that the more heat that is used, the more distortion there will be. This is a main reason why lasers are used for welding, in order to reduce the heat input. But, when there are asymmetric parts there is currently no solution that generates the right amount of heat for each part.
A second challenge related to asymmetric parts is that of gap-bridging - when there is a gap between two parts that needs to be sealed. If, for example, the gap is 50 microns and the laser beam is also 50 microns, it will go straight through the middle and will not seal the edges. The way to solve this situation is either to use a larger laser spot or beam oscillation.
Laser Welding with Dynamic Beam Lasers
Dynamic Beam Lasers provide the flexibility needed to solve these challenges:
Beam Shaping – Using simple software, quickly and easily design any beam shape.
Shape Frequency – Control the frequency of the beam shape from 400Hz –50MHz, which opens a new set of parameters to control the keyhole and melt pool.
Shape Sequence– Design a sequence of shapes to maintain the desired shape orientation relative to the feed direction.
Focus Steering– In addition to the inherent large depth of focus of the SM beam, shift the focus up to 50MHz without any mechanical components.
Dynamic Beam Lasers are the next generation of lasers that will help manufacturers rise above these key welding challenges and produce high quality parts