Customised thermal cycles are heating up laser-based manufacturing
Lasers have become one of the most important tools in industrial manufacturing. They can create very fine features, difficult or impossible to make with conventional machining equipment, and cut materials with negligible impact on the surrounding material, minimising post-processing. Laser beam shaping to control intensity (power per unit area) can overcome current challenges in industrial laser applications and enable fine-tuning of the component’s microstructure and final properties. The EU-funded CUSTODIAN project developed photonics-based laser beam shaping technology tailored to specific materials and applications to control laser processes in real time.
Experiment and simulation inform multi-plane light conversion technology development
The team focused on laser beam welding of stainless-steel automotive components, powder bed fusion for the aeronautics and power generation sectors, and laser cutting of thick steels for multiple sectors. Three crucial preliminary steps laid the foundations for the laser beam shaping technology: 1) determination of the optimal thermal cycle via analysis of both process and material; 2) multiphysics simulation to define the optimal beam shape for achieving the desired thermal cycle; and 3) calculation of the optimum absorption based on Fresnel equations (describing the reflection and transmission of light at an interface) to homogenise the power distribution. The expertise, excellent cooperation and commitment of CUSTODIAN’s partners delivered tremendous and essential insight into these areas. Building on this, project partner Cailabs developed the advanced multi-plane light conversion (MPLC) technology for beam shaping based on the iterative modification of the beam transverse profile after successive reflections onto a phase plate. “MPLC technology comes from the telecommunications sector, and adapting it to industrial laser equipment was not trivial. We had to make important adjustments in the last months of the project and had a very tight final phase for testing and validation of the results,” explains CUSTODIAN project manager Daniel Gesto of AIMEN Technology Centre.
Real-time monitoring and control harnessing high-speed infrared imaging
The technical capability to modify the beam’s shape must be accompanied by the algorithms to do so. CUSTODIAN developed real time monitoring and control systems based on high-speed infrared (IR) imaging. The project’s high-speed IR imagers were integrated coaxially to capture melt pool dynamics in real time. Based on the information extracted, algorithms were developed and tested to adjust process parameters in real time to optimise the thermal cycle for each material.
Solving existing laser problems and opening the door to new applications
CUSTODIAN’s outcomes have demonstrated their potential to address and solve industrial challenges in the field of laser applications that currently cannot be overcome. They will enable better quality and higher productivity while reducing production costs, improving energy efficiency and drastically reducing scrap. Further, they open the door to laser processing of materials inaccessible today due to their chemical composition and microstructure. “The CUSTODIAN methodology combining multiphysics simulation and a flexible laser beam shaping technology (MPLC) is the only way to evaluate and adjust the numerous input parameters in a meaningful way. The project has played a pioneering role in one of the most important topics in laser materials processing today, flexible and application-specific intensity distribution,” concludes Gesto. The shape of things to come can be found in the CUSTODIAN methodology.
Keywords
CUSTODIAN, laser, laser beam shaping, MPLC, multi-plane light conversion, multiphysics simulation, laser beam welding, powder bed fusion
