ANALYSIS: E-MOBILITY
“TRL enables firms to determine the point laser materials processing is ready for an industrial environment”
Figure 2: (top) metal-plastic hybrids with applied laser pre-treatment and (bottom) high- speed camera image of LMD using coaxial wire feeding
as the application in serial production (TRL 7)4
. In this
work the method was used to determine the TRL of currently researched technologies in laser materials processing. The evaluation of the TRL is summarised for this article. A more detailed discussion can be found in the proceedings of the Lasers in Manufacturing Conference 20215
.
Laser beam welding for the production of power electronics For the design and manufacturing of power electronics, laser beam welding (LBW) opens up possibilities due to its high precision and flexibility. To enable the joining of copper with a high process
“Systematic analysis and structured management of production technologies support
efficiency, new laser beam sources emitting radiation in the visible spectrum (blue and green) have been developed in recent years to make use of the higher absorptivity of copper for these wavelengths compared to infrared radiation6
Green laser radiation for example, at a wavelength of 515nm, can be used to join copper to a ceramic substrate, as shown by a metallographic cross section in figure 1a. The evaluation of the current
technological maturity level for LBW in the production of power electronics showed that further experimental investigations are necessary, with consideration to the characteristics of the workpiece, such as the properties of the substrate and the metalised semiconductor. Additionally, further adaptations are necessary to join complex geometries. Combined with the development of suitable methods for automatic inline quality assurance, the high productivity of LBW can be fully exploited to reduce manufacturing costs and enable innovative products in the future.
manufacturing companies”
Digital laser beam welding Digital laser beam welding (DLBW) involves the use of relevant quality characteristics
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derived from real-time process variables – also known as closed loop processing – to fulfill process requirements regarding control and resultant product quality. Process monitoring is becoming increasingly important for this. To a large extent, optical methods are largely suited to process monitoring for DLBW7
.
Low coherence interferometry, for example, allows dimensional quantities of process variables to be recorded inline. This enables the recording of process variables independent from process emissions, which enables precise and temporally highly-resolved geometric measurements. As a result, the surface
topography8 depth9
and the capillary can be assessed despite
process emissions prevailing in the process zone at high intensities. The complex signal structure of the measured inline data requires a holistic investigation of the necessary data processing pipeline – as outlined in figure 1b (based on VDMA (2020)10
) – to use the
measured weld depth profile for the prediction of the surface quality11
.
The evaluation of DLBW’s TRL showed an advanced level of development for already- demonstrated approaches
and systems, indicating that the concept of DLBW can be transferred to series applications for e-mobility in the near future. Further research has to
address the optimisation and qualification of the technology for series production facilities. Based on a technology demonstrator, prototypes have to be integrated into a real production environment to evaluate the full spectrum of possible process and environmental boundary conditions.
Laser-based surface pre- treatment for joining metals and reinforced plastics As shown in figure 2a, laser materials processing can be used for functionalising metallic surfaces to improve the bonding properties to polymers, such as strength12 or tightness13
. The quantitative
evaluation of the technological readiness is oriented towards a subtractive modification using pulsed and continuous- wave (CW) laser radiation as the dominant area of research. Thorough and structured research into theoretical fundamentals of the interaction between the laser radiation and material has been carried out, as indicated in the evaluation of the TRL. Nevertheless, the technology has not yet been widely established in industrial use. In addition to financial aspects, it is not sufficiently qualified towards the particular industry- specific, technical requirements
AUTUMN 2021 LASER SYSTEMS EUROPE 25
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Geiger et al.
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