ISSUE 115 MARCH 2025 OBSERVATIONS


NEW CHALLENGES IN LASER WELDING TECHNOLOGY: A CASE STUDY AXEL LUFT & PRAVIN SIEVI


Axel has rightly noted the interplay between the laser beam source, welding optics and process monitoring systems for battery contact welding. He has pointed-out pros and cons of current manufacturing “philosophies”, and presented the trade off between accuracy in detection, scan field and welding speed, bounded by the technological constraints of the scanning optics.


With no doubt, everyone working in this field is asked to find the “sweet spot” and compromise between beam intensity, processing speed and scan field. This ultimately affects the selection of the power source, energy usage and cost. The presented results are promising, and remarkably the idea of using multiple compact scanners arranged in a rack-like configuration can help cutting system complexity. Since the area of fast scanners in laser beam welding is growing significantly, more articles from AILU in this area would be very welcome also considering the need to integrate optics with new laser sources and beam shaping solutions.


Pasquale Franciosa, University of Warwick


PRE- AND POST-PROCESSING OF Cu-TO- STEEL IN EV BATTERY JOINING


PRATIK SHUKLA


It is challenging to weld dissimilar materials, such as copper to steel, using lasers owing to several differences in their chemistry and thermophysical properties. This article demonstrates the ability to weld, clean, and peen these dissimilar welds. The challenge in welding copper using lasers is made possible and capable of producing acceptable welds by green and blue lasers due to their absorption. Laser cleaning as a preprocessing process before welding, using green laser for copper to steel, is well demonstrated in this work. Blue lasers are used to weld copper to steel because of good absorption, producing high penetration with minimal heat input.


Laser shock peening also increased the compressive residual stress and hardness of the weld. The green and blue lasers can be used for cleaning, peening and welding of dissimilar materials of acceptable quality which is sufficient for the end user requirements. The configurations presented in this article can produce welds with different mechanical properties. By tailoring the laser processing parameters and understanding laser-material interactions, quality and reliable joints with better properties can be produced.


Ragavendran Meenakshisundaram, AMRC North West


SELECTIVE LASER ETCHING: TOWARDS INDUSTRIAL APPLICATION


CALUM ROSS


It was very informative to read this article and find out more about the latest advances in Ultrafast Laser Inscription (ULI) that promises to open new application areas for the Selective Laser Etching (SLE) process. The article outlines well the underpinning technologies to achieve significant advances both in etching selectivity and ULI, i.e. in enabling laser beam shaping and steering technologies, and thus to achieve a better control of the light-material interactions.


In parallel, important advances in post- processing techniques can be deployed to address one of the main issues with the SLE process, i.e. the relatively high surface roughness, and thus to achieve an optical surface quality. Subsequently, it is not surprising that applying ULI and SLE in “tandem” can broaden the application areas of these technologies and make them viable for applications in micro-optics, microfluidics, and optical interconnects. The article even manages to zoom into one new promising application of these technologies, especially the fabrication of micro-structured silica optical fibre preforms. It is really inspirational to learn how ULI and SLE has advanced in recent years.


Stefan Dimov, University of Birmingham


HOW USP LASER SETTINGS DRIVE APPLICATIONS IN EV PRODUCTION


JIM BOVATSEK


This article chimes well with my experience of optimising laser parameters. Until such time as laser parameters can be optimised by neural networks (AI is improving so fast, you won’t have to wait for long!), there is a huge benefit in working with the experts who know the capabilities of the laser inside out.


In Jim’s article, the expert knowledge is applied to the increase of processing speed of battery foils as well as the quality of silicon carbide cutting (scribe and break variety). In both cases, burst mode in ultrafast lasers is used. I recall (ICALEO 2018, Eric Mottay) hearing about the benefits of burst mode in femtosecond laser processes for the first time. Since then, burst mode has gone from being a novelty to a “must have” - but the path to optimisation is tricky.


here that the laser manufacturers have an edge (developing the parameters). Always ask: Can it be done faster? Can it be done better?


Dave MacLellan, AILU


THE LASER USER


LASER-BASED HYBRID MANUFACTURE OF CUSTOMISED STENTS


PETER IBRAHIM & MOATAZ ATTALLAH


Laser Powder Bed Fusion (L-PBF) offers significant advantages for stent manufacturing, including design flexibility, material efficiency, and the potential for smart, bio-inspired implants. It also promotes sustainable manufacturing by reducing waste and energy usage. However, challenges remain, such as maintaining dimensional accuracy for thin-walled structures, handling complex geometries, scalability, and ensuring batch consistency.


This study presents a sequential fabrication process for customised NiTi stents using L-PBF and Laser Micro-Machining (LMM), enabling the creation of thin strut profiles and intricate geometries without thermal or mechanical stress. Key findings include:


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• DOE Optimisation: An energy density of 0.1 J/ mm (150 W, 1.5 m/s) was identified, though more details are needed.


• Scanning Strategies: Continuous scanning produced superior results compared to contour scanning which showed signs of "lack of fusion."


• Surface Finish: Electropolishing improved biocompatibility, though cell type details were missing.


• Mechanical Performance: Finite element modelling demonstrated superior flexibility over traditional S316LVM stents.


Further details on LMM, DOE optimisation, and laser parameters would be beneficial.


Nazanin Mirhosseini, University of Manchester


INDUSTRIAL BEAM SHAPING: SINGLE ELEMENT VS MULTI ELEMENT


NATAN KAPLAN


The article provides a very useful overview of the types of beamshaping and some of the rules and limitations of the approaches. Of course for industrial implementation one of the key questions will be if the beamshaper is cost effective, at which point the specific technological cost and value of the altered beam will need to be compared for a specific process. It is, however, worth emphasising that beamshaping allows for not only improvements in processing but enables processes that are fundamentally not possible without it.


Richard Carter, Heriot-Watt University


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