No design limitations
Almost all laser technology is contactless, unlike existing MIG/MAG TIG technology. This offers a huge advantage in terms of access. A laser beam allows for joints to be made, regardless of whether you have single-sided access or a three-sheet junction.
No post-processing requirements
In the past, welding could pose major problems in the form of product deformations due to the impact of heat. A typical joint in 3mm stainless steel shrinks by around 1mm when welding with TIG. This is reduced to just 0.1mm when using laser technology. This means that the need for post-processing in the form of straightening is removed, while the tolerances of the finished product are much more predictable and consistent over time. A stable process allows for the optimisation of a product’s design.
High level of accuracy results in consistent quality
Today, laser beams can be focused down to a few µm (thousandths of a millimetre). In theory, melting a few µm on each side of a butt joint should be enough to ensure a complete bond. One problem could be positioning the focus relative to the joint so that it hits both sides. We have tolerances in the joints to provide a gap and ensure that the material can move during the process. One way to solve this is to use a larger laser focus, typically between 400 and 600µm to guarantee contact on both surfaces. In order to reduce joint preparation and manipulator requirements, a vision system can be used. Permanova’s proprietary joint tracking system easily positions the focus correctly to ensure an optimal process.
Lasers are easy to automate
To enjoy the full benefit of laser technology, it needs to be automated. In the 1990s, linear systems were mostly used as the optics did not allow the use of robots. With the introduction of fibre-transmitted high-power lasers, robots were able to take over the work. Today, almost all laser machining in the automotive industry uses robots as they are relatively affordable, reliable, and standardised. Automation provides a very high level of technical availability, which results in cost-effective production.
Many of today’s laser applications have replaced methods that use additives. A direct benefit of this is that we can avoid using welding flux and alloys, and we no longer need to transport the additives. Energy consumption when using lasers is around one-seventh of TIG. This results not only in a lower cost of production, but also in less post-processing and all the energy this involves.
In order to meet production needs, it is important to have sufficient capacity. The disadvantage is that this usually requires an increase in investment. In terms of cutting and welding, no method is quicker than using a laser. 6m/min (100mm/s) is a common speed for continuous welding, and it is usually environmental factors that set the limits. Speeds in excess of 20m/min are not uncommon in pipe welding and other applications.
Since laser welding results in fewer deformations, structures can be fully optimised. The only method that could compete here is EB, but the disadvantages come in the form of very limited access, vacuum handling, and long cycle time. For the aerospace industry, the potential for weight reductions has been the driving force in the transition to laser technology.